A novel antiarthritic agent, CCA (lobenzarit disodium), and the role of thymus-derived lymphocytes in the inhibition of rat adjuvant arthritis.

Lobenzarit disodium (CCA) has been reported to have an inhibitory effect on the development of adjuvant arthritis (AA) in rats. Earlier studies have suggested that the therapeutic effect of CCA might be based on its immunoregulatory activity, although the precise mechanisms of action are unclear. In this paper, possible involvement of thymus-derived lymphocytes in the suppression of AA was studied. It was found that CCA failed to inhibit the development of AA in rats whose T lymphocytes were depleted by the injection of rabbit antithymocyte serum (ATS), whereas the same schedule of treatment with CCA significantly suppressed AA developed in control rats which were injected with normal rabbit serum. In addition, adult thymectomy abrogated the antiarthritic effect of CCA. These data suggest the possibility that the therapeutic effect of CCA in AA might be mediated by ATS-sensitive, short-lived, thymus-derived lymphocytes.