Changes in the cellular immune system and circulating inflammatory markers of stroke patients

This study was designed to investigate dynamic changes in the cellular immune system and circulating inflammatory markers after ischemic stroke. Blood was collected from 96 patients and 99 age-matched control subjects for detection of lymphocyte subpopulations and inflammatory markers. We observed decreases in B cells, Th cells, cytotoxic T cells, and NK cells and an increase in regulatory T (Treg) cells in stroke patients on days 1, 3, and 7. Serum levels of TNF-α, C-reactive protein (CRP), IL-4, IL-6, IL-10, IL-17, IL-23, and TGF-β increased, whereas serum level of IFN-γ decreased at all time points after stroke. Stroke patients with infection exhibited a similar tendency toward changes in some lymphocyte subpopulations and inflammatory markers as stroke patients without infection. After controlling for NIH Stroke Scale (NIHSS), we observed no differences in lymphocyte subpopulations between patients with anterior circulation stroke and those with posterior circulation stroke at any time point. The splenic volume correlated positively with the percentages of B cells, Th cells, and cytotoxic T cells, but negatively with Treg cells on day 3 after stroke. Infections were associated with splenic volume, leukocyte counts, percentage of Treg cells, and serum levels of CRP, IL-10, and IFN-γ on day 3. Lesion volume correlated positively with CRP, IL-6, and IL-23, but negatively with IFN-γ on day 3. The NIHSS showed a positive relation with IL-6 and IL-10 on day 3. Ischemic stroke has a profound effect on the systemic immune system that might explain the increased susceptibility of stroke patients to infection.