Preferred superantigens are selected from the group of staphylococcal enterotoxins (SEs), such as SEA, SEB, SEC, SED and SEE, toxoids, active fragments or peptides thereof and other substances having essentially the same mode of action for activating CTLS. The superantigens may include other microbial products (bacterial as well as viral), such as products from staphylococcal strains, e.g. Toxic S