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Focal ischaemia of the rat brain elicits an unusual inflammatory response: early appearance of CD8+ macrophages/microglia

Authors

  • Sebastian Jander,

    1. Department of Neurology and Center for Biological and Medical Research, Heinrich-Heine-University, PO Box 10 10 07,D-40001 Düsseldorf, Germany
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  • Michael Schroeter,

    1. Department of Neurology and Center for Biological and Medical Research, Heinrich-Heine-University, PO Box 10 10 07,D-40001 Düsseldorf, Germany
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  • Donatella D’Urso,

    1. Department of Neurology and Center for Biological and Medical Research, Heinrich-Heine-University, PO Box 10 10 07,D-40001 Düsseldorf, Germany
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  • Clemens Gillen,

    1. Department of Neurology and Center for Biological and Medical Research, Heinrich-Heine-University, PO Box 10 10 07,D-40001 Düsseldorf, Germany
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  • Otto W. Witte,

    1. Department of Neurology and Center for Biological and Medical Research, Heinrich-Heine-University, PO Box 10 10 07,D-40001 Düsseldorf, Germany
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  • Guido Stoll

    1. Department of Neurology and Center for Biological and Medical Research, Heinrich-Heine-University, PO Box 10 10 07,D-40001 Düsseldorf, Germany
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Sebastian Jander, as above.

Abstract

Cerebral ischaemia leads to profound glial activation and leukocyte infiltration into the infarct area. In this study, we provide evidence for a dual macrophage response in focal ischaemic lesions of the rat brain. We show that a considerable proportion of macrophages in the ischaemic lesions express the CD8αβ heterodimer to date only described on CD8+ T cells. As known from other lesion paradigms, CD4+ macrophages were also present. Interestingly, CD8- and CD4-expressing macrophages formed two non-overlapping subpopulations. CD8+ macrophages reached their maximum during the first week with pronounced downregulation thereafter whereas CD4+ cells persisted at high levels into the second week. In contrast to cerebral ischaemia, macrophages in the spleen and in Wallerian degeneration after optic nerve axotomy expressed CD4, but not CD8. In experimental autoimmune encephalomyelitis, CD8 was mainly associated with T cells and very weakly detectable on some ramified cells resembling activated microglia. In conclusion, we show that cerebral ischaemia triggers an unusual inflammatory response characterized by the appearance of CD8+/CD4– macrophages that might exert specific functions in the pathogenesis of ischaemic brain damage.

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