Abstract
Various subpopulations of human peripheral lymphoid cells were tested for their role in the mixed lymphocyte culture (MLC) response. Preparations of lymphocytes enriched for T cells, separated by a rosette sedimentation technique, were usually found to exhibit higher MLC responses than preparation enriched for B cells. The relatively high responses of B-cell-enriched preparations could largely be explained by contaminating T cells (approximately 5%) whose MLC reactivities were strongly enhanced by autologous non-T lymphocytes. Cell preparations enriched for B cells were found to be more potent stimulators of MLC responses than T-cell-enriched preparations in most responder-stimulator cell combinations. An MLC response could only be elicited in the presence of cells with characteristics of monocytes/macrophages. These cells could be derived from cither the responder or the stimulator.