Altered reactivity of immunoglobulin produced by human-human hybridoma cells transfected by pSV2-neo gene

The HB4C5 and HF10B4 cell lines are human-human hybridomas producing human IgM monoclonal antibodies (MAbs) reactive to porcine carboxypeptidase A (CPase), but not to double stranded DNA (ds DNA). We obtained G418-resistant HB4C5 and HF10B4 cells by an introduction of pSV2-neo DNA. Almost all of the G418-resistant clones produced MAbs reactive to not only the CPase but the ds DNA. The results of the inhibition ELISA suggested that the cross-reactivity of the antibodies from G418-resistant clones to CPase and ds DNA was responsible for the alteration on their antigen specificity. HB4C5 and HF10B4 cells and their G418-resistant clones produced antibodies having glycosylated λ chain. The antibodies produced by tunicamycin-treated G418-resistant subclones of HB4C5 and HF10B4 lost the ability to bind to ds DNA, but retained the ability to bind to CPase. These results suggest that an introduction of pSV2-neo DNA into these hybridomas alters the specificities of their MAbs, and that the alteration to antigen binding specificities of their MAbs may be associated with glycosylation of the MAbs by these hybridomas.