Allograft cytotoxicity. Two populations of effector cell detectable by cytolytic and cytostatic assays in vitro.

Using both the 51Cr-release assay to measure cytolysis and the [125I]UdR incorporation assay to detect cytostasis of target cells, two different effector populations have been identified in C57BL10 mice primed to P815Y cells. As expected, the cytolytic cells were T cells possessing a specific surface receptor. After elimination of T cells with specific antisera and complement the cytostatic effector was found to be an adherent cell which lacked an immunologically specific receptor, and exerted significant activity against the C57BL lymphoma, EL4.