H-2-dependent binding of xenogeneic beta  2-microglobulin from culture media.

Sera of C57BL/6 mice contained lymphocytotoxic antibodies after injections with syngeneic lymphoblasts. The antibodies were directed against bovine beta 2-microglobulin, a component of the culture medium, and mimicked H-2-specific antibodies by a preferential recognition of target cells expressing certain H-2 Ag. This "polymorphic" reactivity pattern was due to a variable capacity of H-2 molecules associated with bovine beta 2-microglobulin.