GAMMA-DELTA+ T-CELLS FROM PATIENTS WITH PSORIATIC AND RHEUMATOID-ARTHRITIS RESPOND TO STREPTOCOCCAL ANTIGEN

Objective. To investigate cellular immune responses to streptococcal antigens in patients with psoriatic arthritis (PsA). To specifically examine responses of the gammadelta+ T cell subset. Methods. Proliferation of PsA synovial fluid lymphocytes (SFL) and peripheral blood lymphocytes (PBL) cultured with streptococcal antigen was measured using a H-3 thymidine (H-3Tdr) uptake assay system. Gammadelta+ T cells from PsA PBL and SFL were phenotyped by now cytometry. Following culture with streptococcal antigen, gammadelta+ enriched SFL were sorted by automated flow cytometry and H-3Tdr uptake measured. Results. Patients with PsA and the control group did not differ significantly in their PBL responses to 2 strains of streptococci, one of which was isolated from a patient with guttate psoriasis (Strep 1) and the other from a patient with rheumatic fever (Strep 2). There was also no difference in their responses to a cell wall preparation derived from the former strain. SFL from 8 of 9 patients with PsA responded to both streptococcal strains as did SFL from 3 patients with rheumatoid arthritis (RA). Gammadelta+ SFL from 7 patients with PsA and 3 patients with RA responded only to the psoriasis associated strain. Conclusions. PsA PBL and SFL responded to stimulation by streptococcal antigen but this reactivity was not disease specific. We have demonstrated that gammadelta+ T cells from PsA SF proliferated when cultured with a psoriasis associated strain of streptococcus (Strep 1). However, RA gammadelta+ SFL responded similarly suggesting that gammadelta+ T cell reactivity to streptococcal antigen may be a feature of inflammatory arthritis.