CD4 1 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 1 memory T-cell responses can be terminated when cognate antigen is transgenically expressed in steady-state DC. Transfer of in-vitrogenerated CD4 1 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 1 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.Key words: CD4 1 T cells . DC . Tolerance
See accompanying Commentary by Kurts
IntroductionNegative selection and peripheral tolerance mechanisms jointly serve to limit the development of autoaggressive self-reactive T-cell responses. However, in autoimmune-prone individuals these control mechanisms can fail and autoimmune disease ensues. As autoimmune diseases progress, intra-and intermolecular determinant spreading occurs [1] and populations of effector and memory T cells become established. Therefore, unlike strategies directed at preventing the development of autoimmune disease, where induction of tolerance in naïve T cells may be all that is required, therapies aimed at terminating ongoing autoimmune disease must be capable of inactivating established populations of memory or activated effector T cells.Although naïve T cells are highly dependent on the presence or absence of costimulatory signals to determine the outcome of activation, costimulation appears to play little role in controlling the responses of memory and effector T cells [2,3] and these cells are considered costimulation independent. Because of this, in contrast to naïve T cells which are readily deleted or inactivated in the absence of costimulation memory T cells are widely regarded as potentially resistant to tolerance induction. If this were indeed the case, then effector and memory T cells represent a significant hurdle to therapeutic strategies aimed at treating autoimmune diseases. However, we have recently shown that memory and effector CD8 1 T cells are susceptible to tolerance induction when cognate antigen is expressed in DC and other APC types [4].
2016The relative roles of CD4 1 and CD8 1 T cells in disease progression differ depending on the autoimmune disease bu...