CD27 and Stroke: Our findings mirror this complexity, revealing that while some B‐cell phenotypes, such as CD19 on CD24+ CD27+ B cells, CD19 on memory B cells, and CD26 on immature‐mature B cells, offer neuroprotection, others such as absolute B‐cell counts, CD27 on CD20–CD38– B cells, and CD38 on IgD+ CD24– B cells, are associated with increased stroke risk.