[Effect of phytohemagglutinin on T-lymphocytes isolated from human blood]

T--enriched lymphocyte fraction from normal donors was isolated from heparinized peripheral blood on Ficoll-Urotrast gradients. The mitogenic response of T-lymphocytes in culture was 3 times as high as that of unseparated mononuclear cells. The intensity of blast transformation to PHA did not correlate with the increase of T-lymphocytes in culture. These data suggest that cells of not T-origin may be the limiting factor during mitogenic response of T-lymphocytes to PHA.