Oestrogen induced suppression of collagen arthritis: I. Long term oestradiol treatment of DBA/1 mice reduces severity and incidence of arthritis and decreases the anti type II collagen immune response.

Experimental animal models can be used to help understand how oestrogen modulates autoimmune arthritis. We have previously shown that castration of female DBA/1 mice exaggerates arthritis induced with type II collagen. This report shows that treatment of castrated DBA/1 mice with low doses (0.2 micrograms twice a week) of beta-oestradiol reduces the incidence (37% vs 78% in controls) and severity (3.9 vs 5.6 mean scores) of arthritis. Levels of IgG anti type II collagen antibodies are decreased whereas levels of IgM antibodies are increased in the beta-oestradiol treated mice. The T cell response, as measured by a 3H-thymidine assay, is reduced in the beta-oestradiol treated mice. The results suggest that treatment with low doses of beta-oestradiol exerts a suppressive effect on both development of collagen arthritis as well as T cell dependent immune reactivity towards type II collagen.