Description: MHC Class II antigen is involved in the antigen presentation by APCs for CD4+ cells. It is constitutively expressed on APCs including B cells, macrophages, monocytes and dendritic cells, and is inducible on a number of other cells (endothelium and epithelial cells) by interferon gamma. This antibody is directed against mouse I-A subregion, and it induces the homotypic adhesion of murine B cells in vitro.