ECP-induced DCs efficiently processed and presented tetanus toxoid antigen to responsive autologous CD4 T cells. ECP-induced DCs, from a tetanus-immunized normal subject, efficiently processed and presented tetanus toxoid antigen to fresh autologous magnetic bead-purified CD4 T cells. Whereas autologous CD4 T cells alone or ECP-treated mononuclear cells (containing 8-MOP totally inhibited T cells) yielded limited or no response, respectively, addition of purified fresh CD4 T cells (third bar) enabled a brisk antigen-specific response. This result is representative of the effective presentation of tetanus antigen by ECP-induced DCs from each of 3 normal subjects.