Recently recruited and mature macrophages express CXCL13 that is also associated with extracellular fibrils. Single exposures of multicolor immunofluorescence staining for CXCL13 and various markers (see keys) in inflammatory lesions or germinal centers of normal lymphoid tissue. (A) CXCL13-expressing CD68⁺ macrophages (arrows) in UC lesion, where the CXCL13⁺ meshwork colocalizes with fibronectin (arrowheads). (B) Concentration-matched isotype control for anti-CXCL13 mAb; comparable field from section adjacent to panel A. (C) CXCL13-expressing CD68⁺ macrophages in tonsillar germinal center (arrow) and fibronectin-bearing fibrils with associated CXCL13 (arrowhead). (D) CD68⁺ macrophages in celiac disease lesion do not express CXCL13. (E) CXCL13-expressing CD14⁺ cells (arrows) near small CD20⁺ B-cell follicle (delineated); CXCL13-expressing cells are also present within the follicle where no CD14⁺ cells are seen. Bars represent 50 μm.