Gamma delta + T cells from patients with psoriatic and rheumatoid arthritis respond to streptococcal antigen

To investigate cellular immune responses to streptococcal antigens in patients with psoriatic arthritis (PsA). To specifically examine responses of the gamma delta + T cell subset.

Proliferation of PsA synovial fluid lymphocytes (SFL) and peripheral blood lymphocytes (PBL) cultured with streptococcal antigen was measured using a 3H thymidine (3HTdr) uptake assay system. gamma delta + T cells from PsA PBL and SFL were phenotyped by flow cytometry. Following culture with streptococcal antigen, gamma delta + enriched SFL were sorted by automated flow cytometry and 3HTdr uptake measured.

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). gamma delta + SFL from 7 patients with PsA 3 patients with RA responded only to the psoriasis associated strain.

PsA PBL and SFL responded to stimulation by streptococcal antigen but this reactivity was not disease specific. We have demonstrated that gamma delta + T cells from PsA SF proliferated when cultured with a psoriasis associated strain of streptococcus (Strep 1). However, RA gamma delta + SFL responded similarly suggesting that gamma delta + T cell reactivity to streptococcal antigen may be a feature of inflammatory arthritis.