Lymphocyte-potentiating factor from human peripheral blood adherent cells.

Low-molecular-weight factor, which can restore the diminished concanavalin A (Con A) response of adherent-cell-depleted human peripheral blood lymphocytes, was partially purified from the culture supernatant of human peripheral blood adherent cells by ion-exchange column chromatography, gel filtration and preparative paper chromatography. This factor apparently has a mechanism of action distinct from that of 2-mercaptoethanol. It affects the cells just before the onset of DNA synthesis possibly as one of the second signals in the Con-A-induced activation of human peripheral blood lymphocytes. However, it was demonstrated that the effective activation of lymphoyctes also required the presentation of Con A by adherent cells to lymphocytes at the triggering stage of the activation, indicating that adherent cells have two distinct functions in the Con-A-induced activation of lymphocytes, i.e. the the presentation of Con A to lymphoyctes and the elaboration of soluble factors.