Differential expression of guinea pig class II major histocompatibility complex antigens on vascular endothelial cells in vitro and in experimental allergic encephalomyelitis

Previous studies have shown that vascular endothelial cells do not normally express major histocompatibility complex (MHC) Class II antigens either in vivo or in vitro. In this investigation it was found that endothelial in the central nervous system (CNS) of normal guinea pigs constitutively express MHC Class II antigens recognized by the monoclonal antibodies HLA-DR, 27E7, and MSgp8. This phenotype is retained when these CNS-derived endothelial cells are propagated in tissue culture. Furthermore, examination of CNS tissue taken from animals in the acute phase of chronic relapsing experimental allergic encephalomyelitis shows that additional epitopes of the MHC Class II antigen, detected by the monoclonal antibodies CI.13.1 and 22C4, are present during the diseased state. This study not only demonstrates constitutive expression of certain MHC Class II determinants by guinea pig endothelial cells, but also shows that other Class II determinants can be differentially expressed in certain disease states.