Interactionbetween Major HistocompatibilityComplex Antigens and Epidermal Growth FactorReceptorson Human Cells

Ithas been suggestedthatproducts ofthe major histocompatibility complex, the MHC, ofvertebratesfunctioninmany processesofrecognitionand ligandbindingatthe cell surface.Here we show thatbindingofpolyclonaland monoclonal antibodiesagainsthuman MHC antigens,HLA, reduced the bindingof epidermal growth factor(EGF) to itsmembrane receptorson A-431 tumor cellsand on normal human fibroblasts .Binding of EGF at 37°C similarlyinhibitedthe bindingof Fab fragments and intactIganti-HLA to human cells.The inhibitoryeffectof anti-HLA antibodieswas rapidand dependent upon temperature and antibody concentrationand valence. Fluorescence microscopy qualitatively confirmed the bindingdata and showed thatMHC antigensand EGF-receptorsdo notco-clusterinthe membrane .