Bioassays for IL-α and β commonly utilize the ability of this cytokine to induce IL-2 production by T cell-lines such as EL4.6.1 and LBRM 33, or in primary cultures of thymocytes (LAF assay). Alternatively, IL-1 can be assayed by measuring its ability to stimulate the proliferation of lines such as the subclone DlOS of the murine T-helper cell line D10.64.1 (8). A subclone, NOB-1, of the murine thymoma line EL4.6.l provides a simple and sensitive bioassay for IL-1 (see Figure 1). This line produces IL-2 in response to both human and murine IL-1, which is measured using the CTLL-2 cell-line based assay (see Section 2.1).