EXPRESSION OF HLA-DR IN GRANULOCYTES OF POLYTRAUMATIZED PATIENTS TREATED WITH RECOMBINANT HUMAN GRANULOCYTE MACROPHAGE-COLONY-STIMULATING FACTOR

MHC class II determinants are the restriction elements involved in ant igen-specific activation of helper T lymphocytes and interaction with CD4 molecules. They are typically expressed on a limited number of cel l types, mostly endowed with antigen-presenting capacity. Recently, ex pression of HLA-DR has been detected on granulocytes stimulated ''in v itro'' with GMCSF. However, no evidence of ''in vivo'' expression in h umans has been presented so far. We report here that class II determin ant expression is detectable in vivo on peripheral blood granulocytes of polytraumatized patients upon intravenous administration of rhGM-CS F. Expression of these molecules appears to be an early effect of rhGM -CSF treatment, independent from endotoxemia or endogenous production of IL-6 or TNF-alpha, and rapidly declining upon discontinuation of th erapy. Thus, this treatment might increase the number of cells potenti ally capable of presenting class-II-restricted antigens in these patie nts.