Recombinant Salmonella typhimurium outer membrane protein A and D reactive T cells are expanded in synovial fluid of patients with reactive arthritis and undifferentiated spondyloarthropathy (HUM6P.251)

Abstract

Abstract Introduction: Low molecular weight fractions of outer membrane protein (OMP) of S. typhimurium have been shown to stimulate synovial fluid mononuclear cells (SFMCs) of patients in reactive arthritis (ReA) and undifferentiated spondyloarthropathy (uSpA). By proteomic analysis the stimulatory fractions predicted to consists of 10 proteins including OMPA and OMPD. We studied the frequency of recombinant OMPA and OMPD reactive T cells in the synovial fluid (SF) of patients with ReA/uSpA. Methods: Recombinant OMPA and D were synthesized and SFMCs of 20 patients with ReA/uSpA and 8 patients with rheumatoid arthritis (RA) were cultured with rOMPA/D. IFN-γ and IL17 production by SF T cells was assessed by Flow cytometry and in culture supernatant by ELISA. Antigen specific IFN-γ producing T cells were also enumerated by ELISPOT. A positive response was taken if % cells or Mean spots/well with antigen/Control ≥ 3 Results: Frequency of IFN-γ producing CD8 T cells was increased to crude OMP in 13/20, rOMPA in 9/20 and to rOMPD in 4/20 patients. Frequency of IFN-γ producing CD4 T cells was increased to crude OMP in 6/15, rOMPA in 4/15 and to rOMPD in 2/15 patients. By ELISPOT, 13, 7 and 3 patients showed increased IFN-γ producing SF T cells to crude OMP, rOMPA and rOMPD respectively. IFN-γ and IL17 levels were found to be significantly increased in culture supernatant of cells treated with rOMPA. Conclusion: OMPA is a major antigenic target in patients with Salmonella triggered ReA/uSpA.