Antigen presentation by naive macrophages, dendritic cells and B cells to primed T lymphocytes and their cytokine production following exposure to immunostimulating complexes

SUMMARY Influenza virus envelope proteins incorporated into immunostimulating complexes (iscoms) are taken up and processed by various kinds of antigen‐presenting cells (APC), encompassing peritoneal cells (PEC), unfractionated splenocytes, splenic dendritic cells (DC) or B cells. The iscom‐pulsed naive APC stimulated primed T cells to proliferate and produce cytokine in vitro. In contrast, only DC and B cells pulsed with the same antigen (Ag) in the micelle form functioned as accessory cells stimulating the primed T cells to proliferate and produce cytokine. In general, iscoms were better inducers of cell proliferation than micelles, Iscoms stimulated more secretion of IL‐2 and interferon‐gamma (IFN‐γ) than the micelles, but both antigenic forms stimulated secretion of IL‐4. DC and B cells pulsed with iscoms stimulated most efficiently the secretion of IL‐2 and IFN‐γ, DC were superior to the other APC in stimulating primed T cells to secrete IFN‐γ. On the other hand, micelles stimulated more efficiently than iscoms splenic T cells from micelle‐primed as well as iscom‐primed mice to secrete IL‐10, These data indicate that influenza virus envelope proteins incorporated in iscoms stimulate a broad T cell response, possibly emphasizing a Thl type of response. The same Ag in a micelle form induce a more prominent Th2 type of T cell response. The results indicate that the administration of an Ag in an adjuvant formulation can superimpose a different cytokine profile on the immune response than that induced by the protein Ag alone.