Replacement of T-Cell Function by a T-Cell Product

Abstract

WE have recently shown that the immune response to sheep red blood cells (SRBC) in vitro is T-cell dependent, that is, it can be abrogated by pretreatment of the spleen cells with anti-θ serum and complement¹. We further reported that reconstitution of the system can be achieved by, among other things, the addition of allogeneic thymocytes², while syngeneic thymocytes failed to function as helper cells. Positive allogeneic effects were only obtained if the added thymocytes could recognize the remaining B-cells as foreign. One of the explanations evoked for this allogeneic effect was the participation of a potentiating factor^2,3. It seemed possible that on the heavy antigenic stimulation provided by the histocompatibility antigens carried by the B-cells, added T-cells produce a soluble factor which stimulates the immune response of B-cells to unrelated antigens. We now want to report the existence of two distinct factors, one of which can completely replace T-cells.