Isolation of human spontaneous killer lymphocytes by bacterial adherence.

Human lymphocyte subpopulations (B, T1, T2, T3, and T4 our denomination) have been identified previously by bacterial adherence and differences between them in mitogen responses and specific cytotoxic activity have been found. In this study another aspect has been investigated in order to find functions associated with these subpopulations, namely the spontaneous killing (SK) ability. Freshly isolated human peripheral blood lymphocytes (PBL) were separated into adherent and non-adherent cells following centrifugation against various bact:rial monolayers. The PBL and the resulting subpopulations of PBL were tested alone or in combination as effector cells in a 4 hr cytotoxicity assay against human lymphoblastoid cel- lines of B or T cell origin. The T3 + T4 cells or T4 cells alone showed a significantly higher SK activity against both B and T target cell lines when compared with unseparated PBL, T1 + T2, or T3 cells alone. Whe Fc portion of IgG, contain the lymphocytes responsible for SK activity and that SK cells can be purified by negative selection using bacterial adherence.