Administration of the 2,4-dinitrophenyl (Dnp) determinant conjugated to the "nonimmunogenic" copolymer of D-glutamic acid and D-lysine (D-GL) induces Dnp-specific immunological tolerance which is essentially restricted to bone marrow-derived (B) lymphocytes. Previous studies have demonstrated tolerance induction by Dnp-D-GL in predominantly B lymphocytes of the IgG class. The present studies establish and analyze conditions for tolerance induction in Dnp-specific B lymphocytes of the IgE antibody class by taking advantage of: (i) the relatively easy capacity to induce tolerance with Dnp-D-GL in an animal or cell population previously primed to the Dnp determinant; (ii) previously established parameters for the successful adoptive transfer of Dnp-specific IgE antibody responses; and (iii) the capacity to induce, and maintain a state of Dnp-specific tolerance with Dnp-D-GL in adoptive transfer responses. Using these approaches, we have successfully rendered Dnp-specific B cells of the IgE class profoundly and apparently irreversibly tolerant after exposure of such cells to Dnp-D-GL. These observations represent a starting point of wide potential for solving many therapeutic problems concerned with clinical allergies.