Dipeptidyl peptidase IV and α-naphthylacetate esterase in human T lymphocytes: Cytochemical and biochemical investigations

Abstract

Dipeptidyl peptidase IV (DP IV) activity of human lymphocytes was measured using biochemical assays of cell suspensions and enzyme cytochemical staining of smears from capillary blood and mononuclear cells (MNC). The hydrolysis rate of Gly-Pro-pNA in suspensions of MNC correlates well with the number of DP IV reactive cells as determined by cytochemical staining. MNC from healthy volunteers were shown to contain 44 +/- 10% lymphocytes reactive for DP IV. Using preparations of T lymphocytes and adherent MNC it was shown that DP IV is specific for T lymphocytes. About 60% of T lymphocytes contain DP IV and 94% of DP IV reactive cells form rosettes with sheep erythrocytes. Parallel staining for DP IV and unspecific acid alpha-naphthylacetate esterase (ANAE) yielded nearly the same figure of cells stained for ANAE in a dot-like pattern (50 +/- 10% MNC) as was observed for DP IV. Correlation of both markers indicates that DP IV expressing lymphocytes presumably represent that subpopulation of TM cells which is characterized by a dot-like reaction pattern of ANAE.