Date of Award

2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Microbiology and Immunology

College

College of Graduate Studies

First Advisor

Azizul Haque

Second Advisor

Natalie Sutkowski

Third Advisor

Laura Kasman

Fourth Advisor

Eric Bartee

Fifth Advisor

Sakamuri Reddy

Abstract

Current treatments for B-cell lymphomas are largely non-specific and survival rates among those diagnosed with aggressive subtypes of non-Hodgkin’s lymphoma (NHL) remain poor. Thus, there is a demand for immune therapies that could reduce cyto-toxicity and improve outcomes. While B-cell lymphoma tumor cells express HLA class II molecules, there are multiple defects in functional HLA class II antigen (Ag) presentation to CD4+ T-cells. Studies in our laboratory suggest that in a subtype of non-Hodgkin’s lymphoma, Burkitt’s Lymphoma (BL) there are associated molecules that may disrupt CD4+ T cell recognition of malignant B-cells. To dissect the role of BL-associated molecules in HLA class II Ag presentation, BL shed molecules from multiple BL cell lines were isolated. Furthermore, the functions of these proteins in biochemical and immune evasion by B-cell lymphoma were characterized. This study suggests that many B-cell lymphomas shed a 49 kDa FCRL (Fc Receptor Like)-like molecule that inhibit functional HLA class II Ag presentation to CD4+ T-cells. Chromatography, Western blotting and other biochemical analyses showed that the secreted 49 kDa molecule is FCRLA protein which is primarily expressed in B-cells, and B cell malignancies.. Immunofluorescence and confocal microscopy demonstrated that FCRLA protein may co-localize with HLA-DR molecules, which could suggest that FCRLA may block functional Ag presentation via the MHCclass II pathway. Co-immunoprecipitation and functional Ag presentation assays supported this finding that indeed FCRLA binds to class II proteins and disrupts CD4+ T cell recognition of BL cells. Furthermore, we initiated studies to isolate human monoclonal antibody against a 49 kDa FCRLA molecule that will block inhibitory function of FCRLA and restore class II-mediated immune recognition of BL cells. For these experiments, a sensitive FCRLA screening ELISA was developed, and preliminary library screening validated this approach. These studies suggested that a fully human monoclonal antibody against a 49 kDa FCRLA protein can be isolated for further study. Overall, my data suggest that BL cells secrete a 49 kDa FCRLA protein that inhibits functional HLA class II Ag presentation to CD4+ T-cells. This study also suggests that FCRLA could be a viable protein target for immunotherapy of BL and other B-cell lymphomas.

Rights

All rights reserved. Copyright is held by the author.

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