Abstract: | The influence of the previous cultivation of human peripheral blood mononuclear cells in suspension with mitogen on the consequent PHA-stimulated response in suspension and agar cultures was studied. It has been established that proliferative response of mononuclear cells in suspension with mitogen is not changed, but the intensity of T-cell colony formation in two-layer agar systems in increased after preincubation mainly at the expense of increasing the number of type II colonies and clusters. It is concluded that the free cell-cell contacts are needed to activate T-lymphocyte colony precursors. |