FURTHER CHARACTERIZATION OF AN INTERLEUKIN-2-LIKE CYTOKINE PRODUCED BY XENOPUS-LAEVIS T-LYMPHOCYTES

A T-cell growth factor (TCGF) is produced by antigen- or mitogen-stimu lated T lymphocytes from the South African clawed frog Xenopus laevis. This study further defines the physical and biological properties of this cytokine and demonstrates that TCGF is biochemically similar to m ammalian interleukin-2 (IL-2). Biologically active TCGF eluted from SD S-PAGE displays a M(r) of 16 kD and lectin-affinity chromatography ind icates that the three-dimensional configuration of carbohydrates on TC GF and human IL-2 is similar. Secretion of TCGF is detectable 1 day af ter stimulation of splenocytes with the T-cell mitogen phytohemaggluti nin (PHA) and peaks following 2 to 3 days of stimulation. Finally, des pite the biological and physical similarities between Xenopus TCGF and mammalian IL-2, anti-human IL-2 monoclonal antibodies do not recogniz e Xenopus TCGF.