Hyper IgE in stimulatory graft- versus-host disease: role of interleukin-4.

Intravenous injection of 2 × 10⁸ DBA/2 spleen cells into adult intact (C57BL/6 × DBA/2) Fl mice results in a stimulatory graft-versus-host reaction (GVHR) linked to the recognition by donor CD4⁺ T cells of Ia alloantigens on host B cells. In the experiments presented here, we found that this GVHR is associated with a major increase in IgE serum levels which was already present 7 days after the cell transfer. At 6 weeks, mean IgE levels were more than 200-fold above the control values. Host B cells were responsible for the hypersecretion of IgE in stimulatory GVHR since it was also observed when the DBA/2 donor inoculum was depleted of B cells but not when the Fl recipients were irradiated. The induction of IgE secretion required donor CD4⁺ T cells as treatment of the donor inoculum with lytic anti-CD4 monoclonal antibody (MoAb) completely prevented the occurrence of the hyper IgE whereas depletion of CD8+ cells had no influence on this parameter. The role played by interleukin-4 (IL-4) in this model was analysed in vivo by the administration of the 11B11 anti-IL-4 rat MoAb (total dose 36 mg) during the first 12 days following induction of stimulatory GVHR by 8 × 10⁷ DBA/2 spleen cells. This treatment completely prevented the development of hyper IgE whereas the administration of a control rat MoAb had no significant effect. We conclude that stimulatory GVHR in mice is associated with a major increase in serum IgE which is mediated by IL-4. [ABSTRACT FROM AUTHOR]