Studies on Thymocyte Subpopulations in Guinea Pigs

Abstract

78% of guinea pig thymocytes formed rosettes after 1 h incubation with rabbit erythrocytes. They were separated from nonrosetting cells by layering over a Percoll solution and centrifugation. The nonrosetting cells (RE-) contained a large proportion of spontaneously DNA synthesizing cells as well as cells able to cooperate in a proliferative response to the mitogenic lectins concanavalin A and phytohemagglutinin. In contrast, cells which responded to a thymocyte growth factor were rosette forming (RE⁺). Proliferating thymus cells were earlier shown to reside in a low density population called la. Here we show that, whereas both RE⁺ and RE^–– cells of population la contain proliferating cells, only the RE⁺ respond to the growth factor. Thus, the formation of ‘early’ rosettes can form the basis for enrichment of thymocyte growth factor responsive cells and the simultaneous separation of these from mitogen reactive cells.