Immunoglobulin VH determinants defined by monoclonal antibodies.

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Abstract
Hybridoma clones secreting antibodies against common VH [H-chain variable region] determinants were readily produced by fusion of cells from mice immunized with isolated V.mu. fragments of human Ig, but not with intact Ig molecules or isolated heavy chains. Four monoclonal antibodies to the V.mu. fragments of different IgM paraproteins were selected for analysis: MH-44 (.mu..kappa.), GB-24 (.mu..kappa.), NF-11 (.gamma.1.kappa.) and SA-44 (.gamma.1.kappa.). Each antibody reacted with the homologous V.mu. fragment, homologous .mu. chain and normal .gamma. chains, but not with the intact IgM molecules, intact IgG or isolated L chains, as determined by radioimmunoassay. The VH reaction spectra with a panel of myeloma H chains showed overlapping but distinctive patterns for the 4 antibodies. Each of the 4 monoclonal anit-VH antibodies appeared to react with a different hidden VH determinant that is not exposed on undenatured, intact Ig molecules and differs from conventional VH subgroup determinants. In immunofluorescence studies, the monoclonal anti-VH antibodies did not bind to surface Ig on viable B lymphocytes, but visibly stained subpopulations of fixed B lymphocytes, pre-B cells and normal plasma cells. The mean frequencies of VH+ plasma cells were 30% (MH-44), 17% (GB-24), 13% (NF-11) and 3% (SA-44), and similar frequencies were obtained for the VH+ B cell subpopulations. While subpopulations of B cells were identified at all stages in differentiation by immunofluorescence with the anti-VH antibodies, neigther resting nor activated T cells expressed these VH determinants in detectable amounts.