Recombinant Human Interleukin-2 is a highly purified protein with a molecular weight of approximately 15,300 Daltons. The chemical name is des-alanyl-1, serine-125 Human Interleukin-2. It is produced by recombinant DNA technology using a genetically engineered E. coli strain containing an analog of the human interleukin-2 gene. Genetic engineering techniques were used to modify the Human IL-2 gene, and the resulting expression clone encodes a modified Human IL-2. This recombinant form differs from native Interleukin-2 in following ways: 1) it is not glycosylated; 2) the molecule has no N-terminal alanine; 3) the molecule has serine substituted for cysteine at amino acid position 125; 4) the aggregation state of molecule is likely to be different from that of native IL-2.