The antibody repertoire of early human B cells II: Expression of anti-DNA-related idiotypes

Abstract Cord blood B cells were immortalized in vitro with Epstein-Barr virus (EBV). Supernatants containing > 500 ng/ml IgM from clones/lines were tested for expression of anti-DNA-associated 16 6 and PR4 idiotypes (id) by ELISA. Four of 70 lines, but no clones, were positive for 16 6 id and none expressed the PR4 id. The presence of 16 6 id on four cell lines was associated with specificity for ssDNA, cardiolipin and Fc of IgG. No association was seen with binding to the K30 polysaccharide of Klebsiella . One clone binding this antigen also had anti-ssDNA, anti-Fc and anti-cardiolipin activity but did not express 16 6 id. Our data support the germ-line nature of the 16 6 id and are consistent with the notion that IgM autoantibody-producing B cells use V H genes which are part of the normal B cell repertoire.