Anti-interleukin 2 receptor antibody suppresses delayed-type hypersensitivity to foreign and syngeneic antigens.

Delayed-type hypersensitivity (DTH) requires stimulation of antigen-specific helper T cells (Th). Because de novo expression of the interleukin 2 receptor (IL 2R) is a necessary step in T cell activation, we tested the capacity of anti-mouse IL 2R monoclonal antibody (Mab) and anti-Th Mab (anti-L3T4) to block DTH. We examined the effect of these Mab on two distinct DTH systems, i.e., to foreign hapten (trinitrobenzenesulfonic acid) and to this hapten present on syngeneic blasts. Both anti-IL 2R and anti-L3T4 Mab suppress DTH. Therapy is as effective treating with one injection just before challenge with the hapten as giving six daily injections. These data indicate that DTH is dependent on a discrete subset of activated IL 2R-positive T cells, because anti-IL 2R therapy, which targets few cells, is as effective as anti-L3T4 Mab treatment, which targets the entire Th subset.