THE EXPRESSION OF MURINE CUTANEOUS LATE-PHASE REACTION REQUIRES BOTH IGE ANTIBODIES AND CD4 T-CELLS

Background Exposure of atopic patients to a specific allergen evokes a n immediate response which is followed, in many cases, by a late phase reaction (LPR) some hours later. Here we have examined the immunologi cal mechanisms required for the expression of cutaneous LPR in mice. M ethods BALB/c mice were immunized by i.p. injection of ovalbumin (OVA) and alum actively or by i.v. injection of anti-OVA IgE monoclonal ant ibody (mAb) passively. After challenge by intradermal injection of OVA into ears, the changes in ear thickness, the number of eosinophils, a nd the levels of IL-4 and IFN-gamma protein at the site of antigen cha llenge were examined. Results Actively immunized mice developed a biph asic response at the site of OVA injection, while mice passively immun ized with IgE anti-OVA mAb displayed a strong early response but no LP R. Cell transfer experiments using BALB/c nu/nu mice revealed that bot h OVA-specific IgE mAb and OVA-primed CD4 T cells were required to evo ke LPR. Moreover, LPR was associated with increased levels of IL-4 pro duction concomitant with reduced IFN-gamma production and was abolishe d by pretreatment with anti-IL-4 neutralizing mAb. Conclusion It is su ggested that murine cutaneous LPR against OVA is a type 2 inflammatory response in which both IgE antibodies and CD4 T cells play an obligat ory role.