EXPRESSION OF INTERLEUKIN-2 RECEPTOR-GAMMA ON HUMAN MONOCYTES - CHARACTERIZATION OF LINEAGE-SPECIFIC POSTTRANSLATIONAL MODIFICATIONS

Functional interleukin-2 receptors (IL-2R) on lymphocytes contain both IL-2R beta P and gamma chains. Whereas constitutive expression of IL- 2R beta has been found on monocytes, the expression of IL-2R gamma on these phagocytes has not been examined. We performed reverse-transcrip tion-polymerase chain reaction with Southern blot analysis on RNA deri ved from purified human monocytes and discovered that they constitutiv ely produce IL-2R gamma mRNA. Western immunoblotting revealed 58- and 64-kDa forms of IL-2R gamma on YT-1 and human monocytes, whereas 58-, 64-, and 69-kDa bands were detected using peripheral blood mononuclear cells and non-adherent lymphocytes. These different forms resulted fr om variable N-linked glycosylation since culture of the cells in tunic amycin resulted in detection of a single 39-kDa band which corresponds to the molecular weight predicted from the deduced amino acid sequenc e. By co-immunoprecipitation, the IL-2R beta subunit associates with o nly the 64-kDa IL-2R gamma protein band in monocytes.