M5/114.15.2 monoclonal antibody recognizes a polymorphic determinant shared by I-A[b], I-A[d], I-A[q], I-E[d], I-E[k] MHC class II alloantigens that can be expressed by B cells, dendritic cells, monocytes, macrophages and activated T cells. BD Horizon™ BV480 Rat Anti-Mouse I-A/I-E also reacts with cells from mice of the H-2[p] and H-2[r] haplotypes, and it is non-reactive with cells from NOD (H-2[g7]) mice.