Any gene that determines the ability of lymphocytes to mount an immune response to specific antigens. In the major histocompatibility complex of the mouse (the H-2 complex), the I region contains Ir genes and also codes for Ia (immune-associated) antigens found on B cells and on some T cells and macrophages. In humans, the HLA D (DR) region is the homolog of the mouse H-2 I region. See Chronology, 1948, Snell; 1963, Levine el al.; 1972, Benacerraf and McDevitt.
Subjects: Genetics and Genomics.