Chicken T-cell growth factor: use in the generation of a long-term cultured T-cell line and biochemical characterization.

Supernatants from concanavalin A (Con A)-stimulated chicken spleen cells were used to generate a long-term cultured cell line from antigen-primed chicken peripheral blood leukocytes. This line has been kept in continuous proliferation in vitro for more than 25 weeks. Morphologically these cells were lymphoblastoid and expressed class I and class II antigens of the major histocompatibility complex as well as T-cell (but not B-cell or macrophage) antigens. In addition they contained no peroxidase or non-specific esterase activity, neither were they phagocytic. Proliferation of the line was totally dependent on exogenous T-cell growth factor (TCGF) activity provided by the Con-A-stimulated spleen cell supernatant, comparable with the proliferation of Con-A-induced T-cell blasts. TCGF activity from the supernatant was absorbed both by the long-term cultured T cells and by Con A blasts, demonstrating the presence of receptors for the same TCGF species on the two populations. We have used the long-term cultured cell line to characterize chicken TCGF further. The molecular weight of the biologically active fractions found by gel filtration on Sephadex G-100 was approximately 13,000 and isoelectric focusing showed chicken TCGF to have a pI of pH 5.9. We propose that the TCGF described here is the chicken analogue to the mammalian interleukin 2.