Regulation of antibody production by an antigen-specific EBV-transformed B-lymphoblastoid cell line: effect of high-dose antigen and antigen-pulsed T cells.

A B-cell line (C1B2) secreting monoclonal IgG antibody to influenza virus haemagglutinin (HA3) was obtained by Epstein-Barr virus (EBV) transformation of human tonsillar B cells activated in vitro to influenza A/X31. Antibody secretion by C1B2 was completely inhibited by purified HA3 at concentrations above 100 ng/ml. By contrast, high doses of HA3 had no effect on EBV-transformed B-cell lines making antibody of unrelated specificity. Inhibition of specific antibody secretion by HA3 continued for at least 3 days after the removal of soluble antigen, but this could be partially reversed by treatment with pronase, suggesting that inhibition was due to 'effector cell' blockade by binding of antigen to surface Ig receptors. T cells pulsed with high doses of antigen also suppressed antibody secretion by C1B2, but this effect was probably due to a tolerogenic signal delivered to the B cell by HA3 complexed to the T-cell membrane rather than suppression by antigen-induced Ts, or carryover of free antigen. These experiments demonstrate two independent mechanisms of high-dose tolerance in vitro, and show that monoclonal B-lymphoblastoid lines of known specificity can be used to study regulation of specific antibody production at the level of the B cell.