Targeted depletion of lymphotoxin-alpha-expressing Th1 and Th17 cells inhibits autoimmune disease

Uncontrolled T helper type 1 (T(H)1) and T(H)17 cells are associated with autoimmune responses. We identify surface lymphotoxin-alpha (LT-alpha) as common to T(H)0, T(H)1 and T(H)17 cells and employ a unique strategy to target these subsets using a depleting monoclonal antibody (mAb) directed to surface LT-alpha. Depleting LT-alpha-specific mAb inhibited T cell-mediated models of delayed-type hypersensitivity and experimental autoimmune encephalomyelitis. In collagen-induced arthritis (CIA), preventive and therapeutic administration of LT-alpha-specific mAb inhibited disease, and immunoablated T cells expressing interleukin-17 (IL-17), interferon-gamma and tumor necrosis factor-alpha (TNF-alpha), whereas decoy lymphotoxin-beta receptor (LT-beta R) fusion protein had no effect. A mutation in the Fc tail, rendering the antibody incapable of Fc gamma receptor binding and antibody-dependent cellular cytotoxicity activity, abolished all in vivo effects. Efficacy in CIA was preceded by a loss of rheumatoid-associated cytokines IL-6, IL-1 beta and TNF-alpha within joints. These data indicate that depleting LT-alpha-expressing lymphocytes with LT-alpha-specific mAb may be beneficial in the treatment of autoimmune disease.