Impaired Function of Innate T Lymphocytes and NK Cells in the Acute Phase of Ischemic Stroke

Background: Functional alterations of innate lymphocytes, which can mount rapid immune responses and shape subsequent T cell reactions, were examined in the acute phase of ischemic stroke. Methods: Frequencies, intracellular perforin and interferon-gamma (IFN-gamma) expression of V delta 2 T cells, CD3+ CD56+ natural killer T (NKT)-like and NK cells were examined in the peripheral blood of 20 healthy controls and 28 patients within 6 h of the onset of acute ischemic stroke and after 72 h by flow cytometry. Cytokine production of isolated NKT-like and NK cells following in vitro activation was measured by cytometric bead array. NK cytotoxicity was examined in the peripheral blood mononuclear cells. Results: Percentages of V delta 2, NKT-like and NK cells were constant, and similar to percentages in healthy subjects. In contrast, proinflammatory intracellular IFN-gamma expression by V delta 2 T cells, NKT-like cells and NK cells and IFN-gamma production by isolated NK cells in culture was low at 6 h and reached the level of healthy subjects by 72 h after stroke. Production of anti-inflammatory cytokines was unaltered. Intracellular perforin expression by V delta 2 T cells, NKT-like cells and NK cells, and NK cytotoxicity was low at 6 h, and reached the level of healthy subjects by 72 h. Increases in IFN-gamma and perforin expression by V delta 2 T cells correlated with clinical improvement indicated by decreases in NIHSS scores. Conclusions: Pro-inflammatory and cytotoxic responses of NK, NKT-like and V delta 2 T cells become acutely deficient in ischemic stroke, which may contribute to an increased susceptibility to infections. Copyright (C) 2009 S. Karger AG, Basel