Involvement of FcR triggering in the MWReg30-induced reaction. Hypothermia induced by IV injection of MWReg30 (100 μg) was determined (A) in mice after blocking their FcγRII/III with 2.4G2 MoAb (100 μg; IP) (▪) or in untreated controls (•) and (B) in FcγRIII-deficient mice (▪) compared with untreated control animals (•). The mean values of the body temperatures of 3 mice per group at the indicated times after injection of the antibodies from 1 of 2 experiments are given ± SD.