Escalating-dose peptide immunotherapy induces progressive immunoregulatory changes in self-reactive T cells

Peptide immunotherapy aims to specifically restore tolerance to the administered self-antigen and prevent autoimmunity without the perturbation of normal immune function. We have developed a dose escalation protocol for subcutaneous delivery of the MHC II-restricted myelin basic protein peptide analogue Ac1-9[4Y] to T cell receptor transgenic (Tg4) mice. Dose escalation allows safe administration of high doses of peptide, which effectively induces antigen-specific tolerance and suppresses the development of experimental autoimmune encephalomyelitis, a model for the human condition multiple sclerosis. CD4+ T cells isolated from treated mice are anergic and suppressive in vitro and respond to stimulation by secretion of the immunoregulatory cytokine IL-10. To understand the molecular changes occurring throughout the course of dose-escalation immunotherapy, we undertook microarray analysis of CD4+ T cells at different the stages of treatment, using Tg4 Rag-1 deficient mice, which lack naturally occurring regulatory T cells and have a monoclonal CD4+ T cell population CD4+ T cells were collected from Tg4 Rag1 deficient TCR-transgenic mice at six sequential stages of EDI plus a PBS-treated control, RNA extracted and then subjected to microarray hybridization using Affymetrix Mouse Gene 1.0 ST array