Abstract: The invention relates to immunoconjugates of formula: A—B—(C)n where B may be present or absent, A is a specific binding protein such as an antibody or an antibody binding fragment, or a ligand binding to a receptor present on target cells, B comprises at least one molecule to which “A” and “C” bind, such as an avidin/strepavidin complex, “C” is an MHC molecule, and “n” is a whole number ranging from 1 to 10. The conjugates provide the exquisite binding specificity of antibodies, combined with an ability to stimulate cytotoxic T cells to identify and to destroy cells on which the conjugate is bound and oligomerized. The conjugates are useful both therapeutically and diagnostically.