Time course of the change in intracellular IL1ra expression in monocytes and granulocytes. Anti-D–opsonized RBCs were incubated with leukocytes at a ratio of 500:1 for the indicated times, and intracellular cytokine levels in monocytes (A) and granulocytes (B) were determined after permeabilizing and fixing the leukocytes according to the BD PharMingen protocol. Data are expressed as fold change in intracellular IL1ra expression stimulated by opsonized RBCs (•)or nonopsonized RBCs (○). The results are shown as the means ± SDs of 6 independent experiments. Significance values are indicated (*P = .036; **P = .0002).