Monoclonal antibodies specific for the mouse IgG1 allotypic determinants: reactivity with inbred and outbred mice.

C57BL/6J mice were immunized with an affinity purified monoclonal antibody (IgG1) derived from BALB/c mice and their spleen cells were fused with the mouse myeloma X63.Ag8.653. Two monoclonal antibodies (3A9, gamma 1,kappa and 1C10, gamma 1,kappa) derived from separate fusions were originally found to react with BALB/c monoclonal antibodies expressing a gamma 1 heavy chain isotype but not with other heavy chain isotypes. The results from strain distribution reactivity patterns indicate that these antibodies recognize determinants coded by the allotype locus designated Igh-4a. In a survey of 22 different inbred or congenic strains of mice, no additional polymorphism associated with this locus has been detected. However, allelic polymorphism of the gamma 1 heavy chain allotype does exist in the wild mouse population. The 3A9 and 1C10 antibodies recognize the same determinants (i.e., specificity 1) associated with Igh-4a allotype.