In vitro studies of the rabbit immune system. VIII. The production of rabbit T cell growth factor (TCGF) and its relationship to mouse and human TCGF.

Rabbit spleen cells (1 X 10(6)/ml) stimulated with Con A (2.5 micrograms/ml) begin producing T cell growth factor (TCGF) activity within 2-3 h at 37 degrees C and reach a plateau after 20-24 h. Lymphocytes from the mesenteric lymph nodes (MLN) also produce TCGF activity but require higher lectin and/or cell concentrations for optimal production. TCGF generation by MLN can be improved by including a small proportion of spleen cells (10-40%). Rabbit lymphocytes also produce TCGF in serum-free, protein-free medium, but the Con A concentration must be reduced to 0.5-1.25 micrograms/ml. Rabbit TCGF activity eluted from gel filtration columns at a volume equivalent to approximately 15,000 molecular weight, similar to human TCGF activity. However, when rabbit, mouse and human TCGFs were compared for their ability to support proliferation by activated cells from the 3 species, rabbit and mouse TCGFs appeared more similar. In all cases, the homologous combinations of cells and TCGF were most efficient. Human TCGF would support some proliferative activity in all 3 cell types but rabbit and mouse TCGFs failed to support the growth of human cells.