Alternative versus classical macrophage activation during experimental African trypanosomosis

The type I/type II cytokine balance may influence the development of differ ent subsets of suppressive macrophages, i.e., classically activated macroph ages (caM phi, type I) versus alternatively activated macrophages (aaM phi, type II). Recently, we showed that although mice infected with phospholipa se C-deficient (PLC-/(-)) Trypanosoma brucei brucei exhibit a clear shift f rom type I to the type II cytokine production, wild type (WT)-infected mice remain locked in a type I cytokine response, In the present study, phenoty pe and accessory cell function of macrophages elicited during WT and PLC-/( -) T. b. brucei infection were compared, Results indicate that caM phi deve lop in a type T cytokine environment in the early phase of WT and PLC-/(-) trypanosome infection, correlating with inhibition of T cell activation tri ggered by a mitogen, a superantigen, or an antigen. In the late stage of in fection, only PLC-/(-)-infected mice resisting the infection develop type T T cytokine-associated aaM phi correlating with impaired antigen- but not mi togen- or superantigen-induced T cell activation.