HLA Class I and Class II-Induced Intracellular Signaling and Molecular Associations in Primary Human Endothelial Cells.

The signaling capacity of HLA molecules in vascular cells has been well established. Intracellular signaling and association with the coreceptor integrin β4 has been well-studied for HLA class I. However, little is known regarding HLA class II intracellular signaling in human endothelial cells. Investigation of HLA class II has been challenging due to the loss of HLA class II expression in cultured primary cells. Herein, we describe methods for inducing expression of endogenous alleles and loci of HLA class II molecules, as well as for studying intracellular signaling. This includes siRNA knockdown of proteins and coimmunoprecipitation of putative coreceptors for HLA in primary human aortic endothelial cells.