Non-specific acid esterase activity in rat lymphocytes.

In a first night's collection of rat thoracic duct lymphocytes B- and T-cells were distinguished on cytocentrifuge smears by complementary markers: B-cells by rosette-formation with Staphylococcus aureus Strain Cowan 1 armed with rabbit antiserum to rat F(ab')2 and T-cells by high uptake of 3H-uridine demonstrated by autoradiography. On incubation of the cytocentrifuge smears for demonstration of alpha-naphthyl-acetate esterase (ANAE)-activity, most B-cells showed large, intense colour deposits often located in the uropod. T-cell ANAE-activity on the other hand was variable, possibly due to variations in experimental conditions. When present, the T-cell colour deposits were small, dot-like and of low intensity. ANAE-activity may then be used to differentiate between rat T- and B-cells, being a marker for the latter cell type. This is unexpected as others have reported that ANAE-activity is specific for T-cells in mouse and man. Studies with inhibitors indicate that the rat B-cell enzyme belongs to the acetylesterases.