We previously reported that antigens chemically coupled to the surface of liposomes induced antigen-specific IgG but not IgE antibody production [21, 22] . In addition, antigens chemically coupled to the surface of liposomes consisting of unsaturated fatty acids were presented not only to CD4 + -but also to CD8 + T cells by APCs [23] . Since liposome-coupled antigens induce antiviral immunity [24, 25] , they are expected to be applicable for the development of viral vaccines without inducing antigen-specific IgEs, which cause allergic reactions. In the present study, we investigated the mechanism by which the liposome-coupled antigens were cross-presented by APCs to CD8 + T cells.