The international standard for granulocyte-macrophage colony stimulating factor (GM-CSF). Evaluation in an international collaborative study. Participants of the Collaborative Study.

Two ampouled preparations of granulocyte-macrophage colony stimulating factor (GM-CSF) have been evaluated by twenty nine laboratories in eleven countries for their suitability to serve as international standards for these materials. The preparations were assayed in a wide range of in vitro bioassays and immunoassays. On the basis of results reported here, with the agreement of the participants in the study and with the authorisation of the Expert Committee on Biological Standardization (ECBS) of the World Health Organization (WHO) one of the preparations (88/646) was established as the international standard for GM-CSF.