P-cell stimulating factor: characterization, action on multiple lineages of bone-marrow-derived cells and role in oncogenesis.

T-cell hybridomas have allowed us to define unequivocally a group of 3 distinct molecules, TCGF, T-cell GM-CSF, and PSF, as the products of the activated T-cell. It is becoming increasingly evident that these T-cell-derived molecules, together with a fourth, interferon-gamma, (Wong et al. 1982, 1983), affect a wide range of cell-types. The molecule which we have studied in greatest detail, PSF, probably effects every lineage of non-lymphoid bone-marrow-derived cells. We have evidence that PSF acts in vivo as an important mediator in a pleotropic defence and repair response to antigens that involves all the non-lymphoid elements of the blood. Finally, there is evidence that PSF-dependent cells can become immortal, and that activation and functional expression of the PSF gene can occur in such cells and result in autonomy and tumorigenesis. Clonal sources of T-cell lymphokines and clonal targets for lymphokine assays, formed the basis of recent progress in defining the number and nature of non-antigen-specific T cell products; cloning of the genes coding for these lymphokines should result in a similar impetus to the investigation of the physiology and possible therapeutic role of T-cell lymphokines, and lead to new insights into the control of gene expression and the role of these factors in oncogenesis.