This disclosure relates to methods of inducing a natural killer (NK) cell-mediated immune response and increasing NK activity in a mammal for the treatment of tumors and virus infections, comprising isolating peripheral blood mononuclear cells (PBMCs) from a subject, exposing them in vitro to a protein conjugate comprising granulocyte macrophage colony stimulating factor (GM-CSF) covalently linked to a soluble peptide antigen to activate the PBMCs, and administering the activated PBMCs to the subject. The method also relates to assessing NK cell activity of activated PBMCs to determine whether the subject has had a therapeutically effective response to the protein conjugate.
