Abstract: Interleukin-2 receptor derived from normal and malignant cells has been purified by use of various techniques including affinity chromatography in conjunction with a monoclonal antibody directed to the receptor. The purification process also includes reversed phased high performance liquid chromatography. By these techniques, interleukin-2 receptor has been purified to homogeneity. The high purification of the interleukin-2 receptor has made possible the sequencing of the amino acid residues at the N-terminal of this protein molecule. Double-stranded cDNA is prepared from polyadenylated RNA extracted from cell lines or other sources known to produce IL-2 receptor. The cDNA is inserted within a plasmid vector and then the recombinant plasmid employed to transform an appropriate host. Transformed hosts are identified and grouped into pools.