Temporal regulation of the immune response to LDH-C4 by an X-linked gene in C3H/HeJ and SJL/J mice.

Regulation of the immune response is a complex phenomenon under the control of many genes. This process may be analyzed by comparing the immunogenicity of structurally similar but distinct antigens. Both synthetic immunogens with limited numbers of determinants (1) as well as antigenically complex proteins (2, 3) have been used to study immunoregulatory mechanisms. The LDH iso zymes are particularly interesting because they display a high degree of structural similarity but can be distinguished immunologically. Vertebrate LDH is a tetrameric enzyme. All tissues contain variable amounts of A (or M) and B (or H) subunits which randomly associate to produce five isozymes. The genetic control of the immune response to heterologous LDH-A and -B subunits has been studied in rabbits (4), rats (5), and inbred mice (6, 7). Antiserum to purified LDH-A4 or LDH-B4 reacts only with the isozymes containing the subunits used in immunization but not with the heterologous homotetramer (8, 9).