Reduced Efficacy of Circulating Costimulatory Cells After Focal Cerebral Ischemia

Background and Purpose—Cerebral ischemia is ensued by a cellular immune depression syndrome. The postischemic functional capacity of T lymphocytes is controversial, and interactions between leukocyte subsets are largely unknown. Understanding the immunologic interplay between antigen-presenting cells and lymphocytes as well as between distinct lymphocyte subsets after stroke might be of clinical/therapeutic significance because animal data argue for a cerebroprotective effect of, for example, CD4+CD25+ regulatory T cells. Methods—Ex vivo CD4+ T cell proliferation was analyzed in experimental and human stroke using fluorescence activated cell sorter analysis. To investigate suppressive effects of CD4+CD25+ regulatory T cells as well as the influence of costimulatory cells on CD4+ T cell proliferation, subsets were magnetically sorted before proliferation assay setup. Results—After stroke: (1) proliferation of mouse and human CD4+ T cells on T cell receptor stimulation was unaltered; (2) the suppressive eff...