Late acting T cell depression of high avidity IgG antibody secretion in the secondary response.

Activated T lymphocytes (ATC) suppressed the expression of high avidity plaque-forming cells (PFC) in the secondary immune response when given in vivo 1 day before assay or when mixed in vitro with hyperimmune cells for 90 min before assay. This late acting suppression is a cell dose-dependent, carrier-spedific, T cell-mediated phenomenon. The target of this activity if probably the antibody-secreting cell.