CD46 is a potent co-stimulatory receptor for expansion of human IFN-γ-producing CD8+ T cells

•Activation of CD46 induces rapid down-modulation of CD46 expression on the surface of CD8+ T cells.•CD46 co-stimulation potently induces CD8+ T cell proliferation.•CD46 co-stimulation does not induce a switch to IL-10 production in CD8+ T cells, as is known for CD4+ T cells.•CD46 co-stimulation predominantly expands IFN-γ-producing CD8+ T cells.