Abstract

Neuroinflammation, encompassing both innate and adaptive immune responses, plays a crucial role in ischemic stroke. Although B lymphocytes are central to adaptive immunity, their contributions to ischemic stroke remain poorly understood. Here, we demonstrated that B lymphocytes accumulate in ischemic lesions, forming germinal center–like structures at the later stage after stroke, which mainly depended on in situ proliferation. This accumulation correlated with worsened neuroinflammation and ischemic injury, whereas B cell depletion reduced chronic brain damage during stroke. Mechanistically, microglia recruited B cells into ischemic lesions through MIF-CD74/CXCR4 signaling during the early phase of stroke, while IFN-related pathways in B cells further drove neuroinflammation and brain injury. Targeting these pathways markedly alleviated cerebral ischemia and inflammation. Our findings shed light on the role of B lymphocytes in stroke pathology and suggest promising new avenues for therapeutic intervention.