The following antibodies and reagents were utilized for immunohistochemical analysis of mouse spleen sections: PE-anti-CD4 (GK1.5); FITC-GL7 (RA3-6B2); APC-anti-IgD (all from BD Biosciences). Spleen cryostat sections (5–6 um) were prepared as previously described (15 (link)). Immunohistochemistry was performed as described (15 (link)) and stained sections were analyzed with a Leica DM4000 fluorescence microscope and Leica software (Leica Microsystems, Buffalo Grove, IL). The color intensity of the images was slightly enhanced using Adobe Photoshop CS4 (Adobe Systems, San Jose, CA) for better visualization and was carried out consistently between all sections while maintaining the integrity of the data.