The M5/114.15.2 monoclonal antibody or (M5/114) is specific for the mouse major histocompatibility complex class II, specific for the I-A and I-E subregion-encoded glycoproteins (alloantigens I-Ab, I-Ad, I-Aq, I-Ed, and I-Ek, but not the I-Af, I-Ak, nor I-As antigens). The antibody also reacts with cells from the H-2p or H-2r haplotypes mice.

The polymorphic determinant represented by the mouse major histocompatibility complex class II (MHC Class II) is expressed by the immune cells bearing the specified alloantigens, like T and B lymphocytes, monocytes, dendritic cells, and macrophages. The antibody doesn’t react with the NOD H-2g7 haplotype alloantigens.

M5/114 mAb inhibits I-A-restricted T cell responses of the Haplotypes H-2b, H-2d, H-2q, and H-2u.