Phenotypically and functionally distinct subpopulations of human lymphocytes with T cell markers also exhibit different cytochemical patterns of staining for lysosomal enzymes.

Human peripheral blood lymphocytes that express T cell markers, when reacted for the cytochemical localization of lysosomal acid hydrolases, display two major patterns of staining, i.e., dot-like and scattered granular. Previous attempts to fractionate T cells according to surface markers have yielded populations of cells with heterogeneous patterns of cytochemical staining. In this study, peripheral blood cells forming rosettes with sheep erythrocytes have been fractionated by sequential staining with two monoclonal antibodies, D12 and 2D2, followed by fluorescence-activated cell sorting. These reagents have been shown previously to recognize a subpopulation of cells capable of suppressing T cell proliferation. All of the cells positive for D12 and 2D2 stained for acid hydrolases with the scattered granular pattern, whereas the large majority of the cells negative for both markers stained with the dot-like pattern. It is concluded that suppressor cells within the E+ cell fraction have the cytochemical characteristics of large granular lymphocytes.