Abstract
Dendritic cells (DCs) are strategically positioned to take up antigens and initiate adaptive immunity. One DC subset expresses CD8alphaalpha in mice and is specialized to capture dying cells and process antigens for MHC class I "cross-presentation." Because CD8(+) DCs also express DEC205/CD205, which is localized to splenic T cell regions, it is thought that CD8(+) DCs also are restricted to T zones. Here, we used a new antibody to Langerin/CD207, which colabels isolated CD8(+) CD205(+) DCs, to immunolabel spleen sections. The mAb labeled discrete cells with high levels of CD11c and CD8. Surprisingly most CD207(+) profiles were in marginal zones surrounding splenic white pulp nodules, and only smaller numbers were in T cell areas, where CD205 colabeling was noted. Despite a marginal zone location, CD207(+) DCs lacked identifying molecules for 3 different types of macrophages, localized in proximity and, in contrast to macrophages, marginal zone DCs were poor scavengers of soluble and particulate substrates. After stimulation with microbial agonists, Langerin expression disappeared from the marginal zone at 6-12 h, but was greatly expanded in the T cell areas, and by 24-48 h, Langerin expression disappeared. Therefore, anti-Langerin antibodies localize a majority of CD8(+) DCs to non-T cell regions of mouse spleen, where they are distinct from adjacent macrophages.