Suppressant effect of procarbazine and its comparison with anti-lymphocyte serum in adjuvant-induced polyarthritis in rats.

Procarbazine, a new immunosuppressant, was active in inhibiting the lesions of experimental arthritis in rats. In comparison with anti-lymphocyte serum it was somewhat more effective in suppressing the secondary than the primary lesion of adjuvant-induced disease. The anti-inflammatory action of procarbazine could not be correlated exactly with its immunosuppressant effect. The dosage scheme which began 21 days before immunization and which had the greater effect on the immune response, did not have any greater anti-arthritic effect than the dosage scheme started on day 0. Anti-lymphocyte serum and procarbazine both produced a fall of approximately 75% in the absolute number of circulating lymphocytes, without any significant effect on other elements in the peripheral blood.