The international standards for interleukin-1 alpha and interleukin-1 beta. Evaluation in an international collaborative study.

Three ampouled preparations of interleukin-1 alpha (IL-1 alpha) and three ampouled preparations of interleukin-1 beta (IL-1 beta) were evaluated by 13 laboratories in six countries for their suitability to serve as international standards for these materials. The preparation were assayed in in vitro and in vivo bioassays, radioreceptor assays and immunoassays. On the basis of the results reported here, with the agreement of participants in the study and with the authorization of the Expert Committee on Biological Standardization (ECBS) of the World Health Organization (WHO), one of the preparations of IL-1 alpha and one of the preparations of IL-1 beta were established as international standards for these materials. Further, since the relative activities of IL-1 alpha and IL-1 beta were dependent upon the assay systems used, it was decided that reference should be made to units of IL-1 alpha activity or IL-1 beta activity rather than to IL-1 activity.