Preventive effect of hapten-reactive thymus-derived helper lymphocytes on the tolerance induction in hapten-specific precursors of antibody-forming cells.

The role(s) of helper T lymphocytes in preventing or altering tolerance induction in DNP-specific B lymphocytes was studied. As DNP-reactive helper T cells were reactive against the DNP-portion of the DNP-D-GL molecule, we could probe definitively the physiological role of helper T cells in preventing tolerance induction in B lymphocytes by DNP-D-GL. The results demonstrated that the induction of DNP-specific B cell tolerance by DNP-D-GL can be completely prevented by the presence of DNP-reactive helper T cells, and provide evidence that one critical role of helper T cell participation in humoral responses to antigens is to circumvent the development of a tolerogenic signal that, in the absence of such T cell function, might otherwise ensue after binding of the antigenic determinants by specific B lymphocytes.