Using novel diagnostic antibodies to identify lymphocyte markers of rheumatic fever and heart disease.

Acute rheumatic fever (ARF) is an autoimmune disease that occurs in a subset of patients as a delayed complication of an improperly treated throat infection with a rheumatogenic strain of Streptococcus pyogenes. ARF / Rheumatic heart disease is a leading cause of preventable cardiovascular morbidity and mortality in children worldwide, affecting >33 million people. A method of detecting children susceptible to ARF (3–5% of the total population) would have major global health and economic benefits. One potential ARF diagnostic is the IgM antibody, D8/17, which binds B cells from ARF patients of diverse ethnic groups and geographical locations at a higher % versus matched controls. While this antibody has had mixed results in the past, no group has identified the antigen that D8/17 binds. To aid in this endeavor, we used recombinant antibody engineering to produce new IgM and IgG1 versions of D8/17 that give more consistent results in our in vitrodiagnostic tests. These new derivatives were then utilized in a multi-omics approach to characterize the differences between immortalized B cell lines of ARF patients and controls. Western blot and MS/MS proteomic analyses of lymphocyte lysates identified cytoskeletal proteins from ARF B cells that cross-react more readily with our recombinant D8/17. RNA sequencing and microarray analysis of B cells from ARF patients versus controls confirmed our proteomic results. Further, we discovered differences in the gene expression of other cell surface proteins, kinases and signaling pathways in ARF B cells that bind these antibodies. We hope our analyses will help identify markers or genetic factors related to ARF development and pathogenesis, or aid in designing diagnostic assays for ARF susceptibility. Supported by a grant from the NIH /NIAD (SC2 1SC2AI134947-01)