Description: The Y-Ae antibody reacts with a class II major histocompatibility complex (MHC) self Ea peptide (peptide 52-68) bound to I-Ab molecules. The Y-Ae antibody detects a determinant expressed on a subset of class II I-Ab molecules in strains that also express class II I-Eb. This determinant is expressed on peripheral B cells and on cells in the thymic medulla, but not thymic cortical epithelium. In addition to B cells, the Y-Ae determinant is expressed at comparable levels on other antigen presenting cells, including macrophages and dendritic cells. The antibody does not react with invariant chain-associated class II MHC complexes.
The reactivity of the Y-Ae antibody is MHC-restricted. The Y-Ae antibody was generated by immunization of [B10.MBR x B10.D2]F1 recipients with B10A(5R) LPS blasts. In this strain combination, there is incompatibility for I-Ab and I-Eb molecules. The antibody reacts with 10-15% of surface I-Ab molecules in strains that also express surface I-Eb molecules (e.g., strains B10.A(5R) and B10.A(3R)). The antibody does not react with I-A molecules in strains that have a non-functional I-E (a chain) gene (e.g., strains B6 and B10), nor with mutant I-A molecules (e.g., (B6.c-H-2bm-12 x A.TFR5)F1), nor with any other strain tested. The Y-Ae antibody recognizes an Ea peptide (Ea 52-68) bound to I-Ab molecules, but not to Ea 52-68 peptide bound to I-Ak or I-Abm-12 molecules.