Comparison of the Specific IgM and IgG Antibody Response in Humans Induced by Antigen (Tetanus Toxoid) or a Polyclonal Activator (EBV) in vitro

Culture conditions were established for the reproducible induction of specific antibody responses in vitro using peripheral blood lymphocytes from tetanus toxoid (TT) immunized donors. Maximum anti-TT antibody responses (250-350 ng/ml) were detected on day 9 of culture, with optimum quantities of antigen (0.1-1.0 micrograms/ml TT) or Epstein-Barr virus (EBV). The antigen-driven antibody response unlike the EBV-induced polyclonal response was both T-cell and monocyte-dependent. TT stimulated mainly the IgM class of anti-TT antibody whereas EBV stimulated both IgM and IgG. A combination of TT and EBV caused a partially additive IgM response but suppressed the IgG class of anti-TT antibody. Transfer of cells from 9-day EBV-stimulated cultures to fresh cultures suppressed the anti-TT antibody response, possibly due to elevated levels of OKT8+ suppressor/cytotoxic cells found in culture after EBV infection. These results provide a reliable system for studying B-cell regulation in man.