[Study of the effects of a new vitamin D3 derivative on type II collagen-induced arthritis in an experimental rat model of rheumatoid arthritis].

The effects of a new derivative of vitamin D3, 22-oxa-1 alpha,25-dihydroxyvitamin D3 (OCT), on rheumatoid arthritis was investigated using collagen-induced arthritis in rat, as an experimental model of the disease. Peroral administration of OCT significantly suppressed the incidence of arthritis and inhibited hind-paw-swelling. The levels of IgM and IgG antibodies against Type II collagen in sera were found to decrease in the OCT treated-group. The production of immunoglobulin against Type II collagen from rat spleen cells was also decreased in this group. These immunological effects of OCT on collagen-induced arthritis were more remarkable than those of 1 alpha-hydroxyvitamin D3. These findings indicated that OCT may have a therapeutic value as an immunoregulatory agent for patients with rheumatoid arthritis through inhibition of the autoimmune response to Type II collagen.