Natural cytotoxicity in the guinea-pig: the natural killer (NK) cell activity of the Kurloff cell.

Natural killer (NK) cell activity was found in the various lymphoid compartments of the normal guinea-pig, prominent in the spleen and absent in the thymus. Oestrogen treatment, which increased the Kurloff cell population in blood, spleen and thymus, did not alter NK cell activity in blood and spleen but markedly augmented the lytic capacity of the thymus. Rosetting reactions and selective depletion studies in normal and oestrogen-treated animals revealed the NK cells to belong to a small population of E+ Kurloff cells, some of which were Fc+ and others apparently Fc-. Some of these natural killer cells in the spleen also had receptors for C3 and carried Ig (probably cytophilic). In the lymph nodes, however, the NK cells were found to be E+ lymphocytes, again some of which were Fc+ and others Fc-.