INITIAL CHARACTERIZATION OF SHEEP T-CELL GROWTH-FACTOR AND ITS SPECIES-RESTRICTED ACTIVITY ON HUMAN, RAT, AND MOUSE CELLS

Sheep T-cell growth factor (TCGF) was prepared from concanavalin A-activated sheep peripheral blood cells and subsequently characterized by ammonium sulfate precipitation, gel exclusion chromatography and isoelectric focusing. The TCGF was found in the 60-80% ammonium sulfate fraction and had an apparent MW of 32,500 and an isoelectric point in the range pI 5.2-5.5. The ability of the sheep TCGF to promote proliferation of activated human, sheep, mouse and rat cells was compound with that of human TCGF prepared by phytohemagglutinin stimulation of lymphocytes from multiple donors and TCGF prepared from concanavalin A-stimulated rat and mouse spleen cells. Human TCGF acted across all species barriers, rat TCGF supported the growth of cells of all species except human, and mouse only promoted the growth of activated mouse and rat cells. Sheep TCGF was unique in being unable to support the growth of any cells except autologous cells.