Immunofluorescence analysis of splenic T- and B-cell zones of Townes SS and control mice before and following B microti infection. Representative immunofluorescence images of splenic sections from uninfected (A) and B microti–infected (B) Townes SS and control AA mice (n = 2-3 mice) stained for PNA (a GC marker, using FITC-conjugated PNA, in green), IgD (a B-cell marker, using PE-conjugated anti-IgD, red), and CD3 (a T-cell marker, using APC-conjugated anti-CD3e, blue). Although there is a clear T-cell (blue)/B-cell (red) boundary in the spleens from naive AA mice, T cells are located independently of B-cell follicle, without a clear boundary in the spleens from naive SS mice. GCs marked by PNA in green are formed similarly in both AA and SS mice following Babesia infection. Green arrows indicate clusters of PNA⁺ GC B cells (GCB); white arrows indicate CD3⁺ T cells. Scale bars, 200 μm. FOB, follicular B cell.