Avian lymphokines: an improved method for chicken IL-2 production and assay. A Con A-erythrocyte complex induces higher T cell proliferation and IL-2 production than does free mitogen.

Optimized production conditions and a functional assay of avian T cell growth factor (TCGF) or interleukin 2 (IL-2) are described. Treatment of lymphocytes with mitogen (Con A)-coated chicken red blood cells (MRC) resulted in markedly enhanced mitogenic response and IL-2 secretion compared to stimulation with free Con A. A positive correlation (r = 0.89) was found between mitogenic response and IL-2 activity of conditioned media. Enrichment of target cells, i.e., Con A lymphoblasts, by Percoll consistently improved the sensitivity of the IL-2 assay. The half-life time of chicken IL-2 at 40 degrees C was 9.7 +/- 1.7 h, which was considerably shorter than the value obtained for murine IL-2, i.e., 53.1 +/- 8.5 h. High concentrations of conditioned media were found to contain a dialysable factor that suppressed IL-2 promoted blast proliferation. The relevance of the data for in vitro analysis of T cell function as well as for establishing T cell lines in the chicken system are discussed.