Monoclonal anti-allotype antibody towards BALB/c IgM. Analysis of specificity and site of a V-C crossover in recombinant strain BALB-Igh-Va/Igh-Cb.

Polyclonal IgM obtained by fractionation of a BALB/c serum pool was used as the immunogen for C57BL/6 mice. Draining lymph nodes from selected animals donated cells for fusion with myeloma Sp-2/0. Fifteen hybridomas were productive, and one (RS-3.1) was cloned and the affinity-purified product analyzed for its reactivity pattern by MOPC 104E-enzyme-linked immunosorbent assay inhibition. Among five BALB/c myelomas only TEPC 183 (IgM) was active, not those belonging to other Ig classes. Among normal sera from 8 mouse strains only those of BALB/c, DBA/2J and CBA/J showed inhibition. The recombinant strain BALB-Igh-Va/Igh-Cb did not react, which shows that its C mu stems from parental strain C57BL/6, and that therefore the recombination event had occurred 5' of this gene.