The methods and compounds disclosed herein are useful in treating a subject having cancer or a viral infection by modulating the innate and adaptive immune systems typically by both inhibiting the function of inhibitory receptors and enhancing activity of activating receptors. Preferred therapeutic compositions comprise a carrier； at least one agent selected from the group consisting of: an anti-inflammatory agent, a cytotoxic T cell proliferation agent, or a NK cell proliferation agent； and a therapeutic peptide of the invention. In certain embodiments the compositions further include a second therapeutic peptide and/or an immunoglobulin admixed therewith in an amount sufficient to enhance passive immunoprotection in the subject.
