Peripheral immune cells infiltrating the central nervous system during neuroinflammation.
| Immune cell type | Origin | Entry mechanism | Key functions of CNS | Associated diseases |
|---|---|---|---|---|
| Monocyte-derived macrophages | Circulating monocytes originating from bone marrow hematopoiesis | Migration across blood-brain barrier through adhesion molecules (ICAM-1, VCAM-1) and chemokine signaling | Phagocytosis of cellular debris, production of inflammatory mediators, contribution to tissue remodeling and repair | Multiple sclerosis, stroke, traumatic brain injury [183, 184] |
| CD4+ T cells | Peripheral lymphoid organs | Antigen-dependent migration across inflamed vascular endothelium via chemokine-directed trafficking | Regulation of immune responses through cytokine production, coordination of inflammatory signaling | Multiple sclerosis, viral CNS infections [187] |
| CD8+ T cells | Peripheral lymphoid organs | Recruitment through chemokine gradients and adhesion molecule interactions at the blood-brain barrier | Cytotoxic responses against infected or damaged cells, antigen-specific immune defense | Viral encephalitis, autoimmune neuroinflammation [190, 191] |
| Regulatory T cells (Tregs) | Peripheral immune system, thymus-derived T-cell lineage | Migration to inflamed CNS tissue through chemokine-mediated trafficking | Suppression of excessive inflammation, modulation of immune responses, support of tissue protection and repair | Multiple sclerosis, neurodegenerative disorders [186] |
| Neutrophils | Bone marrow-derived granulocytes | Rapid recruitment through endothelial adhesion molecules and chemokine signaling during acute inflammation | Release of proteases, reactive oxygen species, and inflammatory mediators; contribution to early inflammatory responses | Stroke, traumatic brain injury, infection [188, 192] |
MMN: Conceptualization, Methodology, Investigation, Resources, Data curation, Formal analysis, Visualization, Writing—original draft, Writing—review & editing. The author read and approved the submitted version.
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