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(Stroke. 2009;40:2849.)
© 2009 American Heart Association, Inc.

Original Contributions

The Spectrum of Systemic Immune Alterations After Murine Focal Ischemia

Immunodepression Versus Immunomodulation

Arthur Liesz, MS; Sebastien Hagmann, MD; Carolin Zschoche, MS; Johanna Adamek, MS; Wei Zhou, MD; Li Sun, MD; Andreas Hug, MD; Markus Zorn, MSc; Alexander Dalpke, MD; Peter Nawroth, MD Roland Veltkamp, MD

From the Department of Neurology (A.L., S.H., C.Z., J.A., W.Z., L.S., A.H., R.V.), University Heidelberg, Heidelberg, Germany; the Department of Internal Medicine (M.Z., P.N.), University Heidelberg, Heidelberg, Germany; and the Department of Hygiene and Medical Microbiology (A.D.), University Heidelberg, Heidelberg, Germany.

Correspondence to Roland Veltkamp, MD, Department of Neurology, University Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany. E-mail Roland.Veltkamp{at}med.uni-heidelberg.de

Background and Purpose— Therapeutic modification of the postischemic immune processes is a key target of current experimental stroke research. For successful translation into the clinical setting, experimental studies must account for the impact of different strokes on the immune system including susceptibility to infection. Herein, we characterize the impact of 3 ischemia models on systemic immunological and microbiological parameters.

Methods— In C57Bl/6 mice (n=235), the middle cerebral artery was occluded (MCAO) either permanently by distal coagulation or transiently by an intraluminal filament for 30 minutes or 90 minutes. Differential leukocyte counts were performed in blood and lymphatic organs. Lymphocyte subpopulations and apoptotic cells were characterized by flow cytometry. Blood cytokine concentrations were measured by ELISA. Microbiological cultures were grown from blood and lung samples.

Results— Only extensive infarcts induced leukopenia 24 hours, 3 days and 7 days after MCAO and decreased lymphocyte counts in spleen, lymph nodes and thymus. In contrast, small infarcts led to no significant changes in differential blood count or reduction of overall cell counts in lymphatic organs. Splenic lymphocyte apoptosis and blood cytokine production was significantly increased after extensive lesions compared to mild ischemia. Hypothermia and weight loss occurred only in mice with large infarcts which also suffered from pneumonia and sepsis. In contrast to infarct size, location and side of the infarct did not affect physiological parameters and immune cell alterations.

Conclusions— Postischemic systemic immunomodulation and infectious complications differ substantially among stroke models. Translational studies of immunomodulatory therapies for stroke must account for this heterogeneity.

Key Words: brain ischemia • immune response • leukocytes • cytokines • bacterial infection