T suppressor lymphocytes regulation of adjuvant arthritis in two inbred strains of rats

Adjuvant arthritis can be induced by a single injection of Freund's complete adjuvant (FCA) in the highly susceptible Lewis (LEW) rat strain, but not the resistant Wistar A.G. (WAG) strain. This strain-dependent susceptibility to the disease is correlated with differences in T suppressor cells regulation. In WAG rats, indeed, the in vitro response in LEW alloantigens was highly inhibited 11 days after FCA injection, while LEW rats in vitro response to WAG alloantigens was slightly increased. Furthermore, spleen cells from WAG rats given FCA 4 days before exhibited T cell-mediated active suppression of WAG in vitro response to LEW alloantigens when they were co-cultured with WAG normal spleen cells. This suppression was abolished by removal of T cells on nylon wool column. A previous irradiation of these T cells also inhibited their suppressive effect, suggesting that FCA-induced suppression might be due to soluble suppressor factor(s). On the other hand T cells from FCA treated LEW rats did not produce any modification of LEW in vitro response to WAG alloantigens. This suggests that the severe arthritis induced in LEW rats could be correlated with a defect of their suppressor cells functions, while in WAG rats FCA activated suppressor T cells could control the disease.