Abnormality of the post-proline-cleaving enzyme activity in mice with systemic lupus erythematosus-like syndrome.

Previous studies indicated the importance of hydrolytic enzymes in the pathogenesis of autoimmune diseases. In the present study, we examined the activities of such enzymes in various organs of the hybrids of the New Zealand Black and New Zealand White mouse (NZB/W mouse) as a laboratory model of human systemic lupus erythematosus. Of the 18 enzymatic activities tested, the activities of the post-proline-cleaving enzyme showed a particular behavior in the spleen of NZB/W mouse. The enzymatic activity progressively increased with age in contrast to the reverse tendency in the control. This phenomenon was not found in any organs other than the spleen. The activity of this enzyme showed a high level of correlation to that of proline-iminopeptidase in most organs tested from control animals. However, these correlations were almost completely absent in the spleen of NZB/W mice. This may suggest an important pathogenetic role for the post-proline-cleaving enzyme in immunological disturbances in this model animal.