Functional Heterogeneity of Splenic T Lymphocyte Subpopulations I. Determination of Splenic Subpopulations by the Use of Mitogenic Probes

The results reported here suggest that there exist two T-cell-mitogenic responsive populations in the spleen--one that is responsive to concanavalin A (Con A) and a second one that is responsive to Con A and phytohemagglutinin (PHA). Using an in vitro restimulation system, we have found that a primary in vivo activation with Con A effectively suppresses the subsequent restimulation response to PHA. However, in the reverse experiment, a primary in vivo PHA activation had little effect on the ability of cells to be restimulated with Con A. The suppression seen was due to a refractory recovery period displayed by all cells after previous activation and not to a nonspecific steric hindrance of mitogenic activation receptors due to the lectin remaining on the cell surfaces.