T cell dependent and independent steps in IgE-B memory cell development

The role of T cells in the IgE antibody response was studied using athymic nu/nu mice which failed to form IgE antibody against either T-dependent or T-independent antigens. Evidence was obtained that hapten-specific B cells can be primed with T-dependent or T-independent antigens in the absence of T cells. Transfer of nu/nu spleen cells primed with alum-absorbed dinitrophenyl (DNP) ovalbumin or DNP derivatives of Salmonella bacilli into irradiated nu/+ mice, together with unprimed T cells, enhanced IgE antihapten antibody response of the recipients to alum-absorbed DNP-KLH. The antigen-primed nu/nu spleen cells, however, did not contain hapten-specific B memory cells directly committed to IgE response, since no antihapten IgE antibody response was obtained when the same DNP-primed nu/nu spleen cells were transferred into irradiated mice, together with KHL-primed nu/+ spleen cells, and the recipients were challenged with DNP-KLH without adjuvant. Once IgE-B memory cells responded to DNP derivatives of both T-dependent and T-independent carriers to form a significant amount of antihapten IgE antibody without participation of T cells. The results indicate that the essential role of T helper cells in the IgE antibody response is in the process of the development of IgE-B memory cells.