Induction of human IgE synthesis by a factor derived from T cells of patients with hyper-IgE states.

The requirements for the induction of IgE synthesis in normal B cells were studied. In contrast to peripheral blood lymphocytes (PBL) from allergic subjects, normal PBL failed to synthesize IgE spontaneously in vitro. Pokeweed mitogen (PWM) and Epstein Barr virus (EBV) failed to induce IgE synthesis in normal PBL and in tonsil lymphocytes. In the case of PWM, this failure was not overcome by prior removal of T8+ cells, which were shown previously to contain IgE-specific suppressor cells. In the case of EBV, the failure to induce IgE synthesis was not overcome by prior removal of sheep rosette-forming cells. Supernatants of T cells derived from three groups of patients with elevated serum IgE (hyper-IgE syndrome, atopic dermatitis, and acute graft-vs-host disease) induced significant IgE synthesis in cultures of normal B cells without causing an increase in IgE synthesis. In contrast, supernatants of normal T cells failed to induce IgE synthesis. Release of the IgE isotype-specific helper factor was inhibited by cycloheximide and tunicamycin, and its activity was destroyed by treatment with trypsin and neuraminidase. These results indicate that whereas classical polyclonal B cell activators (PWM, EBV) fail to induce IgE synthesis by normal B cells, IgE synthesis is readily induced by an IgE-specific helper factor released by T cells from patients with hyper-IgE states.