Enzymehistochemical staining of T mu lymphocytes for glycyl-proline-4-methoxy-beta-naphthylamide-peptidase (DAP IV).

Human T mu lymphocytes are detected in a histochemical reaction with glycyl-proline-4-methoxy-beta-naphthylamide-peptidase (DAP IV; EC 3.4.14.4). DAP IV occurs in 59.4 +/- 8.25 of human T lymphocytes in blood and marrow. Direct biochemical assays were in accord with the cytochemical findings. DAP IV-positive lymphocytes accounted for 89.5 +/- 0.6% of T-lymphocytes bearing Fc receptor for IgG contained 11.3 +/- 8.3% T-lymphocytes bearing Fc receptor for IgM.