nutch_noindex
CANCELAR
COVID-2019 Alert

Information about the 2019 Novel Coronavirus. Read the latest >

Información sobre el coronavirus 2019 (COVID-19). Aprenda más >

/nutch_noindex

Tho Pham, MD

  • No hay imagen

Especialidades médicas y/o especialidades quirúrgicas

Anatomic & Clinical Pathology

Trabajo y educación

Educación

University of California, San Diego, San Diego, CA 92093, 06/30/2009

Primeros años de residencia

Stanford University Pathology Residency, Stanford, CA, 6/30/2010

Últimos años de residencia

Stanford University Hospital and Clinics, Stanford, CA, 6/30/2013

Subespecialidad

Stanford University Hospital and Clinics, Stanford, CA, 6/30/2014

Certificado(s) de especialidad

Anatomic & Clinical Pathology, American Board of Pathology

Blood Banking/Transfusion Medicine, American Board of Pathology

Todo Publicaciones

SARS-CoV-2 RNAemia in a Healthy Blood Donor 40 Days After Respiratory Illness Resolution. Annals of internal medicine Pham, T. D., Huang, C., Wirz, O. F., Rltgen, K., Sahoo, M. K., Layon, A., Pandey, S., Foung, S. K., Boyd, S. D., Pinsky, B. A. 2020

View details for DOI 10.7326/L20-0725

View details for PubMedID 32678685

Symptomatic SARS-CoV-2 infections display specific IgG Fc structures. medRxiv : the preprint server for health sciences Chakraborty, S., Edwards, K., Buzzanco, A. S., Memoli, M. J., Sherwood, R., Mallajosyula, V., Xie, M. M., Gonzalez, J., Buffone, C., Kathale, N., Providenza, S., Jagannathan, P., Andrews, J. R., Blish, C. A., Krammer, F., Dugan, H., Wilson, P. C., Pham, T. D., Boyd, S. D., Zhang, S., Taubenberger, J. K., Morales, T., Schapiro, J. M., Parsonnet, J., Wang, T. T. 2020

Abstract

The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has caused a public health crisis that is exacerbated by our poor understanding of correlates of immunity. SARS-CoV-2 infection can cause Coronavirus Disease 2019 (COVID-19), with a spectrum of symptoms ranging from asymptomatic carriage to life threatening pneumonia and cytokine dysregulation [1-3]. Although antibodies have been shown in a variety of in vitro assays to promote coronavirus infections through mechanisms requiring interactions between IgG antibodies and Fc gamma receptors (FcRs), the relevance of these observations to coronavirus infections in humans is not known [4-7]. In light of ongoing clinical trials examining convalescent serum therapy for COVID-19 patients and expedited SARS-CoV-2 vaccine testing in humans, it is essential to clarify the role of antibodies in the pathogenesis of COVID-19. Here we show that adults with PCR-diagnosed COVID-19 produce IgG antibodies with a specific Fc domain repertoire that is characterized by reduced fucosylation, a modification that enhances interactions with the activating FcR, FcRIIIa. Fc fucosylation was reduced when compared with SARS-CoV-2-seropositive children and relative to adults with symptomatic influenza virus infections. These results demonstrate an antibody correlate of symptomatic SARS-CoV-2 infections in adults and have implications for novel therapeutic strategies targeting FcRIIIa pathways.

View details for DOI 10.1101/2020.05.15.20103341

View details for PubMedID 32511463

View details for PubMedCentralID PMC7252581

Optimizing O-negative RBC utilization using a data-driven approach. Transfusion Virk, M. S., Lancaster, D., Quach, T., Lim, A., Shu, E., Belanger, G., Pham, T. D. 2020

Abstract

O-negative red blood cells (ON-RBC) are a precious resource and the international blood banking community has become increasingly concerned with its inappropriate utilization. AABB recently made several recommendations to address the issue. Solutions must be multifaceted and involve donor centers, blood banks, and clinical departments. From the perspective of a hospital blood bank, it is difficult to rely solely on increased donor recruitment and ubiquitous blood typing of the entire in-patient population. We therefore focused on interventions within the blood bank to optimize inventory and policies to ensure appropriate ON-RBC utilization.Transfusion data over one year was examined for the rate of out-of-group/inappropriate ON-RBC. Furthermore, we assessed whether that rate was related to product life on the day of transfusion. We also examined our stock inventory levels and how excess inventory can contribute to inappropriate ON-RBC usage.The ON-RBC inventory level was decreased in order to reduce the rate of inappropriate transfusions while maintaining a safe level for optimal patient care. Compared to baseline, our intervention caused ON-RBCs to be transfused earlier in their shelf-life (9.27 vs. 11.15days from expiration [DFE], p = 0.0012). This reduced the overall rate of inappropriate ON-RBC transfusions (67% vs. 54%, p = 0.0035), approximating 185units of ON-RBC saved over the course of 6 months.A data-driven approach to optimize stock inventory levels is widely applicable; it can be adopted by numerous institutions to improve utilization and establish a benchmark for the broader blood banking community.

View details for DOI 10.1111/trf.15713

View details for PubMedID 32077488

High-Titer Isohemagglutinins in Platelet Donors Jacob, R., Wang, D., Hodghead, K., Pham, T. WILEY. 2019: 53A54A
A FLOW CYTOMETRY BASED ABO-BLOOD GROUP ANTIBODY ASSAY (FABO-AB) FOR PREDICTING HEMOLYSIS IN ABO-MISMATCHED BONE MARROW TRANSPLANTATION (BMT) Liu, H., Nguyen, K. D., Virk, M. S., Pham, T. D., Chen, G. ELSEVIER SCIENCE INC. 2019: 40
Shaping of infant B cell receptor repertoires by environmental factors and infectious disease. Science translational medicine Nielsen, S. C., Roskin, K. M., Jackson, K. J., Joshi, S. A., Nejad, P., Lee, J., Wagar, L. E., Pham, T. D., Hoh, R. A., Nguyen, K. D., Tsunemoto, H. Y., Patel, S. B., Tibshirani, R., Ley, C., Davis, M. M., Parsonnet, J., Boyd, S. D. 2019; 11 (481)

Abstract

Antigenic exposures at epithelial sites in infancy and early childhood are thought to influence the maturation of humoral immunity and modulate the risk of developing immunoglobulin E (IgE)-mediated allergic disease. How different kinds of environmental exposures influence B cell isotype switching to IgE, IgG, or IgA, and the somatic mutation maturation of these antibody pools, is not fully understood. We sequenced antibody repertoires in longitudinal blood samples in a birth cohort from infancy through the first 3 years of life and found that, whereas IgG and IgA show linear increases in mutational maturation with age, IgM and IgD mutations are more closely tied to pathogen exposure. IgE mutation frequencies are primarily increased in children with impaired skin barrier conditions such as eczema, suggesting that IgE affinity maturation could provide a mechanistic link between epithelial barrier failure and allergy development.

View details for PubMedID 30814336

Shaping of infant B cell receptor repertoires by environmental factors and infectious disease SCIENCE TRANSLATIONAL MEDICINE Nielsen, S. A., Roskin, K. M., Jackson, K. L., Joshi, S. A., Nejad, P., Lee, J., Wagar, L. E., Pham, T. D., Hoh, R. A., Nguyen, K. D., Tsunemoto, H. Y., Patel, S. B., Tibshirani, R., Ley, C., Davis, M. M., Parsonnet, J., Boyd, S. D. 2019; 11 (481)
Molecular Characterizations of Anti-ABO Blood Group Antibodies Nguyen, K., Pham, T., Boyd, S. WILEY. 2018: 22A
Streamlining a blood center and hospital transfusion service supply chain with an informatics vendor-managed inventory solution: development, implementation, and 3-month follow-up TRANSFUSION Tsang, H. C., Garcia, A., Scott, R., Lancaster, D., Geary, D., Anh-Thu Nguyen, Shankar, R., Buchanan, L., Pham, T. D. 2018; 58 (7): 171825

Abstract

The ordering process at Stanford Health Care involved twice-daily shipments predicated upon current stock levels from the blood center to the hospital transfusion service. Manual census determination is time consuming and error prone. We aimed to enhance inventory management by developing an informatics platform to streamline the ordering process and reallocate staff productivity.The general inventory accounts for more than 50 product categories based on characteristics including component, blood type, irradiation status, and cytomegalovirus serology status. Over a 5-month calibration period, inventory levels were determined algorithmically and electronically. An in-house software program was created to determine inventory levels, optimize the electronic ordering process, and reduce labor time. A 3-month pilot period was implemented using this program.This system showed noninferiority while saving labor time. The average weekly transfused:stocked ratios for cryoprecipitate, plasma, and red blood cells, respectively, were 1.03, 1.21, and 1.48 before the pilot period, compared with 0.88, 1.17, and 1.40 during (p=0.28). There were 27 (before) and 31 (during) average STAT units ordered per week (p=0.86). The number of monthly wasted products due to expiration was 226 (before) and 196 (during) units, respectively (p=0.28). An estimated 7 hours per week of technologist time was reallocated to other tasks.An in-house electronic ordering system can enhance information fidelity, reallocate and optimize valuable staff productivity, and further standardize ordering. This system showed noninferiority to the labor-intensive manual system while freeing up over 360 hours of staff time per year.

View details for PubMedID 29770454

Big data modeling to predict platelet usage and minimize wastage in a tertiary care system PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Guan, L., Tian, X., Gombar, S., Zemek, A. J., Krishnan, G., Scott, R., Narasimhan, B., Tibshirani, R. J., Pham, T. D. 2017; 114 (43): 1136873

Abstract

Maintaining a robust blood product supply is an essential requirement to guarantee optimal patient care in modern health care systems. However, daily blood product use is difficult to anticipate. Platelet products are the most variable in daily usage, have short shelf lives, and are also the most expensive to produce, test, and store. Due to the combination of absolute need, uncertain daily demand, and short shelf life, platelet products are frequently wasted due to expiration. Our aim is to build and validate a statistical model to forecast future platelet demand and thereby reduce wastage. We have investigated platelet usage patterns at our institution, and specifically interrogated the relationship between platelet usage and aggregated hospital-wide patient data over a recent consecutive 29-mo period. Using a convex statistical formulation, we have found that platelet usage is highly dependent on weekday/weekend pattern, number of patients with various abnormal complete blood count measurements, and location-specific hospital census data. We incorporated these relationships in a mathematical model to guide collection and ordering strategy. This model minimizes waste due to expiration while avoiding shortages; the number of remaining platelet units at the end of any day stays above 10 in our model during the same period. Compared with historical expiration rates during the same period, our model reduces the expiration rate from 10.5 to 3.2%. Extrapolating our results to the 2 million units of platelets transfused annually within the United States, if implemented successfully, our model can potentially save 80 million dollars in health care costs.

View details for PubMedID 29073058

Occult Hemolytic Anemia Due to Anti-Mur in a Patient Receiving Blood from a Region with a Prominent Asian Donor Population Oak, J., Mallari, R., de Asis, M., Shu, E., Hughes, J., Pham, T. WILEY. 2017: 178A
Normalizing Microbiota-Induced Retinoic Acid Deficiency Stimulates Protective CD8(+) T Cell-Mediated Immunity in Colorectal Cancer. Immunity Bhattacharya, N., Yuan, R., Prestwood, T. R., Penny, H. L., DiMaio, M. A., Reticker-Flynn, N. E., Krois, C. R., Kenkel, J. A., Pham, T. D., Carmi, Y., Tolentino, L., Choi, O., Hulett, R., Wang, J., Winer, D. A., Napoli, J. L., Engleman, E. G. 2016; 45 (3): 641-655

Abstract

Although all-trans-retinoic acid (atRA) is a key regulator of intestinal immunity, its role in colorectal cancer (CRC) is unknown. We found that mice with colitis-associated CRC had a marked deficiency in colonic atRA due to alterations in atRA metabolism mediated by microbiota-induced intestinal inflammation. Human ulcerative colitis (UC), UC-associated CRC, and sporadic CRC specimens have similar alterations in atRA metabolic enzymes, consistent with reduced colonic atRA. Inhibition of atRA signaling promoted tumorigenesis, whereas atRA supplementation reduced tumor burden. The benefit of atRA treatment was mediated by cytotoxic CD8(+) Tcells, which were activated due to MHCI upregulation on tumor cells. Consistent with these findings, increased colonic expression of the atRA-catabolizing enzyme, CYP26A1, correlated with reduced frequencies of tumoral cytotoxic CD8(+) Tcells and with worse disease prognosis in human CRC. These results reveal a mechanism by which microbiota drive colon carcinogenesis and highlight atRA metabolism as a therapeutic target for CRC.

View details for DOI 10.1016/j.immuni.2016.08.008

View details for PubMedID 27590114

View details for PubMedCentralID PMC5132405

Human B-cell isotype switching origins of IgE JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY Looney, T. J., Lee, J., Roskin, K. M., Hoh, R. A., King, J., Glanville, J., Liu, Y., Pham, T. D., Dekker, C. L., Davis, M. M., Boyd, S. D. 2016; 137 (2): 579-?

Abstract

B cells expressing IgE contribute to immunity against parasites and venoms and are the source of antigen specificity in allergic patients, yet the developmental pathways producing these Bcells in human subjects remain a subject of debate. Much of our knowledge of IgE lineage development derives from model studies in mice rather than from human subjects.We evaluate models for isotype switching to IgE in human subjects using immunoglobulin heavy chain (IGH) mutational lineage data.We analyzed IGH repertoires in 9 allergic and 24 healthy adults using high-throughput DNA sequencing of 15,843,270 IGH rearrangements to identify clonal lineages of Bcells containing members expressing IgE. Somatic mutations in IGH inherited from common ancestors within the clonal lineage are used to infer the relationships between Bcells.Data from 613,641 multi-isotype B-cell clonal lineages, of which 592 include an IgE member, are consistent with indirect switching to IgE from IgG- or IgA-expressing lineage members in human subjects. We also find that these inferred isotype switching frequencies are similar in healthy and allergic subjects.We found evidence that secondary isotype switching of mutated IgG1-expressing Bcells is the primary source of IgE in human subjects, with lesser contributions from precursors expressing other switched isotypes and rarely IgM or IgD, suggesting that IgE is derived from previously antigen-experienced Bcells rather than naive Bcells that typically express low-affinity unmutated antibodies. These data provide a basis from which to evaluate allergen-specific human antibody repertoires in healthy and diseased subjects.

View details for DOI 10.1016/j.jaci.2015.07.014

View details for Web of Science ID 000369235500028

Single B-cell deconvolution of peanut-specific antibody responses in allergic patients JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY Hoh, R. A., Joshi, S. A., Liu, Y., Wang, C., Roskin, K. M., Lee, J., Pham, T., Looney, T. J., Jackson, K. J., Dixit, V. P., King, J., Lyu, S., Jenks, J., Hamilton, R. G., Nadeau, K. C., Boyd, S. D. 2016; 137 (1): 157-167

Abstract

The frequencies, cellular phenotypes, epitope specificity, and clonal diversity of allergen-specific B cells in patients with food allergy are not fully understood but are of major pathogenic and therapeutic significance.We sought to characterize peanut allergen-specific B-cell populations and the sequences and binding activities of their antibodies before and during immunotherapy.B cells binding fluorescently labeled Ara h 1 or Ara h 2 were phenotyped and isolated by means of flow cytometric sorting from 18 patients at baseline and 13 patients during therapy. Fifty-seven mAbs derived from allergen-binding single B cells were evaluated by using ELISA, Western blotting, and peptide epitope mapping. Deep sequencing of the B-cell repertoires identified additional members of the allergen-specific B-cell clones.Median allergen-binding B-cell frequencies were 0.0097% (Ara h 1) or 0.029% (Ara h 2) of B cells in baseline blood from allergic patients and approximately 3-fold higher during immunotherapy. Five of 57 allergen-specific cells belonged to clones containing IgE-expressing members. Almost all allergen-specific antibodies were mutated, and binding to both conformational and linear allergen epitopes was detected. Increasing somatic mutation of IgG4 members of a clone was seen in immunotherapy, whereas IgE mutation levels in the clone did not increase.Most peanut allergen-binding B cells isolated by means of antigen-specific flow sorting express mutated and isotype-switched antibodies. Immunotherapy increases their frequency in the blood, and even narrowly defined allergen epitopes are recognized by numerous distinct B-cell clones in a patient. The results also suggest that oral immunotherapy can stimulate somatic mutation of allergen-specific IgG4.

View details for DOI 10.1016/j.jaci.2015.05.029

View details for Web of Science ID 000367724300006

Normalizing microbiota-induced retinoic acid deficiency stimulates protective CD8+ T-cell-mediated immunity in colorectal cancer Immunity Bhattacharya, N., Yuan, R., Prestwood, T., Penny, H., DiMaio, M., Reticker-Flynn, N., Krois, C., Kenkel, J., Pham, T., Carmi, Y., Tolentino, L., Choi, O., Hulett, R., Wang, J., Winer, D., Napoli, J., Engleman, E. 2016; 45: 64155

Abstract

Although all-trans-retinoic acid (atRA) is a key regulator of intestinal immunity, its role in colorectal cancer (CRC) is unknown. We found that mice with colitis-associated CRC had a marked deficiency in colonic atRA due to alterations in atRA metabolism mediated by microbiota-induced intestinal inflammation. Human ulcerative colitis (UC), UC-associated CRC, and sporadic CRC specimens have similar alterations in atRA metabolic enzymes, consistent with reduced colonic atRA. Inhibition of atRA signaling promoted tumorigenesis, whereas atRA supplementation reduced tumor burden. The benefit of atRA treatment was mediated by cytotoxic CD8(+) Tcells, which were activated due to MHCI upregulation on tumor cells. Consistent with these findings, increased colonic expression of the atRA-catabolizing enzyme, CYP26A1, correlated with reduced frequencies of tumoral cytotoxic CD8(+) Tcells and with worse disease prognosis in human CRC. These results reveal a mechanism by which microbiota drive colon carcinogenesis and highlight atRA metabolism as a therapeutic target for CRC.

View details for DOI 10.1016/j.immuni.2016.08.008

View details for PubMedCentralID PMC5132405

How do I implement an automated screen for high-titer ABO antibody as an inventory management tool for ABO plasma-incompatible platelets? TRANSFUSION Fontaine, M. J., Webster, J., Gomez, S., Pham, T. D., Goodnough, L. T., Galel, S. A. 2015; 55 (12): 2783-2789

Abstract

Plasma volume reduction (PVR) may reduce the risk of hemolysis associated with transfusion of plateletpheresis blood products (PLTs) containing ABO-incompatible plasma. But PVR may delay PLT issue. In collaboration with our blood donor center we evaluated an automated screen of PLT for high-titer ABO antibody and to apply PVR to high-titer PLTs.At the donor center, plasma from PLT donors was tested using an automated microplate system (PK7300, Beckman). PK settings were set for a detection cutoff equivalent to 1 in 256 using a manual tube method. The donors associated with high-titer PLTs were characterized by sex and age. In the transfusion service, the number of PVR procedures was evaluated before and after implementation of the high-titer screen.During validation, 157 of 1008 PLT units (15%) were positive by the automated method versus 121 (12%) by manual method. After implementation, 2112 of 15,240 PLT units were high-titer, with higher frequency in donations from females versus males (18% vs. 12%, p<0.0001). The PLT PVR rate was reduced by 50%.Implementation of an automated method to screen PLTs for high-titer ABO antibody at the donor center improves the inventory management of PLTs containing ABO-incompatible plasma at the hospital transfusion service.

View details for DOI 10.1111/trf.13374

View details for Web of Science ID 000367950600004

IgH sequences in common variable immune deficiency reveal altered B cell development and selection. Science translational medicine Roskin, K. M., Simchoni, N., Liu, Y., Lee, J., Seo, K., Hoh, R. A., Pham, T., Park, J. H., Furman, D., Dekker, C. L., Davis, M. M., James, J. A., Nadeau, K. C., Cunningham-Rundles, C., Boyd, S. D. 2015; 7 (302): 302ra135-?

Abstract

Common variable immune deficiency (CVID) is the most common symptomatic primary immune deficiency, affecting ~1 in 25,000 persons. These patients suffer from impaired antibody responses, autoimmunity, and susceptibility to lymphoid cancers. To explore the cellular basis for these clinical phenotypes, we conducted high-throughput DNA sequencing of immunoglobulin heavy chain gene rearrangements from 93 CVID patients and 105 control subjects and sorted nave and memory B cells from 13 of the CVID patients and 10 of the control subjects. The CVID patients showed abnormal VDJ rearrangement and abnormal formation of complementarity-determining region 3 (CDR3). We observed a decreased selection against antibodies with long CDR3s in memory repertoires and decreased variable gene replacement, offering possible mechanisms for increased patient autoreactivity. Our data indicate that patient immunodeficiency might derive from both decreased diversity of the nave B cell pool and decreased somatic hypermutation in memory repertoires. The CVID patients also exhibited an abnormal clonal expansion of unmutated B cells relative to the controls. Although impaired B cell germinal center activation is commonly viewed as causative in CVID, these data indicate that CVID B cells diverge from controls as early as the pro-B stage, cell and suggest possible explanations for the increased incidence of autoimmunity, immunodeficiency, and lymphoma CVID patients.

View details for DOI 10.1126/scitranslmed.aab1216

View details for PubMedID 26311730

View details for PubMedCentralID PMC4584259

IgH sequences in common variable immune deficiency reveal altered B cell development and selection. Science translational medicine Roskin, K. M., Simchoni, N., Liu, Y., Lee, J., Seo, K., Hoh, R. A., Pham, T., Park, J. H., Furman, D., Dekker, C. L., Davis, M. M., James, J. A., Nadeau, K. C., Cunningham-Rundles, C., Boyd, S. D. 2015; 7 (302): 302ra135-?

Abstract

Common variable immune deficiency (CVID) is the most common symptomatic primary immune deficiency, affecting ~1 in 25,000 persons. These patients suffer from impaired antibody responses, autoimmunity, and susceptibility to lymphoid cancers. To explore the cellular basis for these clinical phenotypes, we conducted high-throughput DNA sequencing of immunoglobulin heavy chain gene rearrangements from 93 CVID patients and 105 control subjects and sorted nave and memory B cells from 13 of the CVID patients and 10 of the control subjects. The CVID patients showed abnormal VDJ rearrangement and abnormal formation of complementarity-determining region 3 (CDR3). We observed a decreased selection against antibodies with long CDR3s in memory repertoires and decreased variable gene replacement, offering possible mechanisms for increased patient autoreactivity. Our data indicate that patient immunodeficiency might derive from both decreased diversity of the nave B cell pool and decreased somatic hypermutation in memory repertoires. The CVID patients also exhibited an abnormal clonal expansion of unmutated B cells relative to the controls. Although impaired B cell germinal center activation is commonly viewed as causative in CVID, these data indicate that CVID B cells diverge from controls as early as the pro-B stage, cell and suggest possible explanations for the increased incidence of autoimmunity, immunodeficiency, and lymphoma CVID patients.

View details for DOI 10.1126/scitranslmed.aab1216

View details for PubMedID 26311730

How do I implement an automated screen for high-titer ABO antibody as an inventory management tool for ABO plasma-incompatible platelets? Transfusion Fontaine, M. J., Webster, J., Gomez, S., Pham, T. D., Goodnough, L. T., Galel, S. A. 2015; 55 (12): 278389

Abstract

Plasma volume reduction (PVR) may reduce the risk of hemolysis associated with transfusion of plateletpheresis blood products (PLTs) containing ABO-incompatible plasma. But PVR may delay PLT issue. In collaboration with our blood donor center we evaluated an automated screen of PLT for high-titer ABO antibody and to apply PVR to high-titer PLTs.At the donor center, plasma from PLT donors was tested using an automated microplate system (PK7300, Beckman). PK settings were set for a detection cutoff equivalent to 1 in 256 using a manual tube method. The donors associated with high-titer PLTs were characterized by sex and age. In the transfusion service, the number of PVR procedures was evaluated before and after implementation of the high-titer screen.During validation, 157 of 1008 PLT units (15%) were positive by the automated method versus 121 (12%) by manual method. After implementation, 2112 of 15,240 PLT units were high-titer, with higher frequency in donations from females versus males (18% vs. 12%, p<0.0001). The PLT PVR rate was reduced by 50%.Implementation of an automated method to screen PLTs for high-titer ABO antibody at the donor center improves the inventory management of PLTs containing ABO-incompatible plasma at the hospital transfusion service.

View details for PubMedID 26448376

Single B-cell deconvolution of peanut-specific antibody responses in allergic patients. The Journal of allergy and clinical immunology Hoh, R. A., Joshi, S. A., Liu, Y., Wang, C., Roskin, K. M., Lee, J. Y., Pham, T., Looney, T. J., Jackson, K. J., Dixit, V. P., King, J., Lyu, S. C., Jenks, J., Hamilton, R. G., Nadeau, K. C., Boyd, S. D. 2015

Abstract

The frequencies, cellular phenotypes, epitope specificity, and clonal diversity of allergen-specific B cells in patients with food allergy are not fully understood but are of major pathogenic and therapeutic significance.We sought to characterize peanut allergen-specific B-cell populations and the sequences and binding activities of their antibodies before and during immunotherapy.B cells binding fluorescently labeled Ara h 1 or Ara h 2 were phenotyped and isolated by means of flow cytometric sorting from 18 patients at baseline and 13 patients during therapy. Fifty-seven mAbs derived from allergen-binding single B cells were evaluated by using ELISA, Western blotting, and peptide epitope mapping. Deep sequencing of the B-cell repertoires identified additional members of the allergen-specific B-cell clones.Median allergen-binding B-cell frequencies were 0.0097% (Ara h 1) or 0.029% (Ara h 2) of B cells in baseline blood from allergic patients and approximately 3-fold higher during immunotherapy. Five of 57 allergen-specific cells belonged to clones containing IgE-expressing members. Almost all allergen-specific antibodies were mutated, and binding to both conformational and linear allergen epitopes was detected. Increasing somatic mutation of IgG4 members of a clone was seen in immunotherapy, whereas IgE mutation levels in the clone did not increase.Most peanut allergen-binding B cells isolated by means of antigen-specific flow sorting express mutated and isotype-switched antibodies. Immunotherapy increases their frequency in the blood, and even narrowly defined allergen epitopes are recognized by numerous distinct B-cell clones in a patient. The results also suggest that oral immunotherapy can stimulate somatic mutation of allergen-specific IgG4.

View details for PubMedID 26152318

Human B-cell isotype switching origins of IgE. The Journal of allergy and clinical immunology Looney, T. J., Lee, J. Y., Roskin, K. M., Hoh, R. A., King, J., Glanville, J., Liu, Y., Pham, T. D., Dekker, C. L., Davis, M. M., Boyd, S. D. 2015

Abstract

B cells expressing IgE contribute to immunity against parasites and venoms and are the source of antigen specificity in allergic patients, yet the developmental pathways producing these Bcells in human subjects remain a subject of debate. Much of our knowledge of IgE lineage development derives from model studies in mice rather than from human subjects.We evaluate models for isotype switching to IgE in human subjects using immunoglobulin heavy chain (IGH) mutational lineage data.We analyzed IGH repertoires in 9 allergic and 24 healthy adults using high-throughput DNA sequencing of 15,843,270 IGH rearrangements to identify clonal lineages of Bcells containing members expressing IgE. Somatic mutations in IGH inherited from common ancestors within the clonal lineage are used to infer the relationships between Bcells.Data from 613,641 multi-isotype B-cell clonal lineages, of which 592 include an IgE member, are consistent with indirect switching to IgE from IgG- or IgA-expressing lineage members in human subjects. We also find that these inferred isotype switching frequencies are similar in healthy and allergic subjects.We found evidence that secondary isotype switching of mutated IgG1-expressing Bcells is the primary source of IgE in human subjects, with lesser contributions from precursors expressing other switched isotypes and rarely IgM or IgD, suggesting that IgE is derived from previously antigen-experienced Bcells rather than naive Bcells that typically express low-affinity unmutated antibodies. These data provide a basis from which to evaluate allergen-specific human antibody repertoires in healthy and diseased subjects.

View details for PubMedID 26309181

Effects of Aging, Cytomegalovirus Infection, and EBV Infection on Human B Cell Repertoires JOURNAL OF IMMUNOLOGY Wang, C., Liu, Y., Xu, L. T., Jackson, K. J., Roskin, K. M., Pham, T. D., Laserson, J., Marshall, E. L., Seo, K., Lee, J., Furman, D., Koller, D., Dekker, C. L., Davis, M. M., Fire, A. Z., Boyd, S. D. 2014; 192 (2): 603-611

Abstract

Elderly humans show decreased humoral immunity to pathogens and vaccines, yet the effects of aging on B cells are not fully known. Chronic viral infection by CMV is implicated as a driver of clonal T cell proliferations in some aging humans, but whether CMV or EBV infection contributes to alterations in the B cell repertoire with age is unclear. We have used high-throughput DNA sequencing of IGH gene rearrangements to study the BCR repertoires over two successive years in 27 individuals ranging in age from 20 to 89 y. Some features of the B cell repertoire remain stable with age, but elderly subjects show increased numbers of B cells with long CDR3 regions, a trend toward accumulation of more highly mutated IgM and IgG Ig genes, and persistent clonal B cell populations in the blood. Seropositivity for CMV or EBV infection alters B cell repertoires, regardless of the individual's age: EBV infection correlates with the presence of persistent clonal B cell expansions, whereas CMV infection correlates with the proportion of highly mutated Ab genes. These findings isolate effects of aging from those of chronic viral infection on B cell repertoires and provide a baseline for understanding human B cell responses to vaccination or infectious stimuli.

View details for DOI 10.4049/jimmunol.1301384

View details for Web of Science ID 000329224000006

View details for PubMedID 24337376