B cell and T cell areas are mostly unaltered by LTβR-Ig treatment, but CD21 staining is diminished. Representative spleens from untreated (a, d, g), treated (8 mg/kg LTβR-Ig) (b, e, h), and recovery animals (8 mg/kg treatment followed by 3-month recovery) (c, f, i) were stained with anti-CD20 Ab’s (blue). Sections were costained with anti-CD3 Ab’s (brown) (a–c), or the FDC-specific clone CNA.42 (brown) (d–f), or the CD21-specific R42/3 clone (dark brown) (g–i). Spleens were photographed at ×100. T, T cell zone; T/B interface, T cell/B cell interface.