Purification and partial sequence analysis of human interleukin-2 derived from peripheral blood leukocytes

Human peripheral blood leukocyte-derived interleukin-2 (IL-2) was resolved by DEAE-cellulose column chromatography into three peaks of activity, IL-2A, B, and C, with isoelectric points of 7.2, 6.6, and 7.9, respectively. IL-2 A, B, and C were further purified by reverse phase high performance liquid chromatography and resolved into two apparently homogeneous peaks each with identical molecular weight: A-1 and A-2 (Mr17000); B-1 and B-2 (Mr17500); and C-1 and C-2 (Mr14400). The amino acid compositions and partial NH2-terminal amino acid sequences of these molecular species were consistent with those predicted from IL-2 cDNA sequences derived from Jurkat and peripheral blood leukocytes.