Monoclonal anti‐V_H antibodies recognize a common V_H determinant expressed on immunoglobulin heavy chains from various species

Our previous work using rabbit antibodies to the variable region of MOPC315 myeloma heavy chain (V_H) has indicated the existence of framework determinant(s) common to many murine heavy chains. Here we report the characterization of anti‐V_H monoclonal antibodies (mAb) prepared in an attempt to elucidate the nature of the common V_H determinant. We immunized AKR/J mice with a purified V_H315 fragment and generated somatic cell hybrids by the fusion of the immune AKR/J splenocytes with the NS1 myeloma cells. Thirty‐seven common anti‐V_H and 57 subgroup V_HI‐specific hybridomas have been established and characterized. Whereas the anti‐subgroup mAb seemed to react with a determinant unique to the MOPC315 (mouse V_HI) subgroup, all the anti‐V_H mAb reacted with myeloma heavy chains of different V_H subgroups, class and allotypes. Antibody competition studies revealed that the V_H subgroup determinants are distinct from the common V_H determinants and that both were also recognized by the rabbit polyclonal antibodies. The common V_H determinants were found to be “hidden” determinants on intact immunoglobulin molecules being exposed only on isolated heavy chains. Furthermore, they are sequential determinants since they are preserved on fully denatured heavy chains. The common V_H determinants are shared by immunoglobulins of a wide range of vertebrates from amphibia to man and thus represent antigenic structures which were highly conserved throughout evolution.