Serological identification of an Ir-region product

Reciprocal immunization of congenic lines differing in the middle portion of the H-2 complex leads to the production of antibodies which react with an antigen or antigens controlled by the Ir region. The antigen designated Ir-1.1 seems to be present only on a subpopulation of lymphocytes from lymph nodes and spleen. It is absent on bone marrow cells.