Activities of dipeptidyl peptidase II and dipeptidyl peptidase IV in mice with lupus erythematosus-like syndrome and in patients with lupus erythematosus and rheumatoid arthritis.

We examined the activities of peptidases in plasma and tissues of the New Zealand Black (NZB) mouse as an animal model of human systemic lupus erythematosus, and also in serum from patients with rheumatoid arthritis and systemic lupus erythematosus. Activities of dipeptidyl peptidase II (DAP II) and post-proline cleaving enzyme (PPCE) were increased, and dipeptidyl peptidase IV (DAP IV) activity was decreased in plasma and spleen of NZB mice, as compared with the control BALB/c mice. Likewise, the activity of DAP II was increased and that of DAP IV was decreased in serum of patients with rheumatoid arthritis and systemic lupus erythematosus. These results indicate the importance of hydrolytic enzymes in the pathogenesis of autoimmune diseases.