Dipeptidyl amino peptidase IV cytochemistry in circulating lymphocytes from HIV-I-seropositive subjects

In order to assess whether changes in the relative proportions of cells pertaining to different T-lymphocyte subsets correlate with dipeptidyl amino peptidase IV (DAP IV) activity, the enzyme was cytochemically investigated in circulating lymphocytes from 20 HIV-I-seropositive drug addicts. Although on the average, a significant reduction of lymphocyte DAP IV activity was found in comparison with healthy control subjects, wide variations between individual cases were observed, and no obvious relationship emerged between DAP IV staining on one hand, immunocytological findings and Walter Reed staging on the other. Therefore, in view of the preliminary results reported, the variations of lymphocyte DAP IV activity in the course of HIV I infection seem to deserve further investigation, in order to clarify both the biological significance of this reaction and its possible clinical relevance.