Studies on the Source and Action of the T-Cell Replacing Factor (TRF)

Abstract

We have recently reported that in the in vitro system of Mishell and Dutton (1) in which normally the 19s response is strongly T-cell dependent (2) the T-cell function can be replaced by a soluble factor (3). This soluble factor was derived from supernates of allogeneic spleen cells incubated for 24 hrs. and was called T-cell replacing factor, TRF. Our published data showed that the formation of TRF was dependent on the presence of T-cells and we suggested that TRF was actually a T-cell product. To substantiate this idea we now used allogeneic cells from different sources, that is, spleens, lymph nodes and thymus. Since the thymocytes contain a very small number of mature cells (4) which might be expected to participate in TRF production, the product derived from allogeneic thymocytes was fivefold concentrated.