Role of cell-cell interactions in mitogenic stimulation of lymphocytes. I. Dissociation on concanavalin A-inducible lymphocyte activation and agglutination.

The aim of the study was to decide whether the delayed agglutination of lymphocytes following mitogenic doses of concanavalin A (Con A) is a prerequisite of the activation process. It was shown that both phenomena can be greatly dissociated; suitable doses of cytochalasin B (CB) completely block agglutination, while the capacity to respond (by [14C]thymidine incorporation) to Con A-induced stimulation is retained. It was concluded that agglutinability is acquired in the early phase of the activation process, concomitant with induced changes in the cell membrane structure; the manifestation (i.e. agglutination) of this capacity is not necessary for the activation of the cell nucleus to take place, and it depends on the cells' chances of being brought together, either by active movement or by external forces.