Engagement of the B7 family of molecules on antigen-presenting cells with their T cell–associated ligands, CD28 and CD152 (cytotoxic T lymphocyte–associated antigen-4 [CTLA-4]), provides a pivotal costimulatory signal in T-cell activation. We investigated the role of the CD28/CD152 pathway in psoriasis in a 26-week, phase I, open-label dose-escalation study. The importance of this pathway in the generation of humoral immune responses to T cell–dependent neoantigens, bacteriophage φX174 and keyhole limpet hemocyanin, was also evaluated. Forty-three patients with stable psoriasis vulgaris received 4 infusions of the soluble chimeric protein CTLA4Ig (BMS-188667). Forty-six percent of all study patients achieved a 50% or greater sustained improvement in clinical disease activity, with progressively greater effects observed in the highest-dosing cohorts. Improvement in these patients was associated with quantitative reduction in epidermal hyperplasia, which correlated with quantitative reduction in skin-infiltrating T cells. No markedly increased rate of intralesional T-cell apoptosis was identified, suggesting that the decreased number of lesional T cells was probably likely attributable to an inhibition of T-cell proliferation, T-cell recruitment, and/or apoptosis of antigen-specific T cells at extralesional sites. Altered antibody responses to T cell–dependent neoantigens were observed, but immunologic tolerance to these antigens was not demonstrated. This study illustrates the importance of the CD28/CD152 pathway in the pathogenesis of psoriasis and suggests a potential therapeutic use for this novel immunomodulatory approach in an array of T cell–mediated diseases.
Judith R. Abrams, Mark G. Lebwohl, Cynthia A. Guzzo, Brian V. Jegasothy, Michael T. Goldfarb, Bernard S. Goffe, Alan Menter, Nicholas J. Lowe, Gerald Krueger, Michael J. Brown, Russell S. Weiner, Martin J. Birkhofer, Garvin L. Warner, Karen K. Berry, Peter S. Linsley, James G. Krueger, Hans D. Ochs, Susan L. Kelley, Sewon Kang