Steady-state antigen-expressing dendritic cells terminate CD4+ memory T-cell responses

CD4(+) T cells are important effectors of inflammation and tissue destruction in many diseases of immune dysregulation. As memory T cells develop early during the preclinical stages of autoimmune and inflammatory diseases, immunotherapeutic approaches to treatment of these diseases, once established, must include the means to terminate memory T-cell responses. Traditionally, it has been considered that, due to their terminally differentiated nature, memory T cells are resistant to tolerance induction, although emerging evidence indicates that some immunotherapeutic approaches can terminate memory T-cell responses. Here, we demonstrate that CD4(+) memory T-cell responses can be terminated when cognate antigen is transgenically expressed in steady-state DC. Transfer of in-vitro-generated CD4(+) memory T cells establishes, in nontransgenic recipients, a stable and readily recalled memory response to cognate antigen. In contrast, upon transfer to mice expressing cognate antigen targeted to DC, memory CD4(+) T cells undergo a phase of limited proliferation followed by substantial deletion, and recall responses are effectively silenced. This finding is important in understanding how to effectively apply immunotherapy to ongoing T-cell-mediated autoimmune and inflammatory diseases.