A soluble form of the Interleukin-6 receptor (IL-6R) was initially identified in the urine of healthy adult humans, in culture supernatants from HTLV-I positive T cell lines and in the serum of HIV-seropositive blood donors. These soluble receptors (Interleukin-6 receptor) may develop as a result of alternate splicing of the mRNA or as a result of proteolytic cleavage and release of the membrane-bound form of the receptor. Recombinant, Human IL-6 Soluble Receptor was produced by cloning the cDNA of the IL-6R and introducing a stop codon into the cDNA sequence immediately preceding the transmembrane domain.