Expression of mucosal homing receptor alpha 4 beta 7 is associated with enhanced migration to the Chlamydia-infected murine genital mucosa in vivo

The CD4 T helper cell type 1 (Th1) response is essential for the resolution of chlamydial genital infection in mice, However, not all Th1 clones are e qually protective in eradicating the infection, Since oral immunization reg imens produce protective immunity, we evaluated the role of the mucosa-asso ciated homing receptor, alpha 4 beta 7, in trafficking to the genital mucos a, Using a panel of CD4, Th1 cell lines and clones, we compared the Lymphoc yte homing patterns of a Chlamydia-specific, protective clone (P-MoPn), a n onprotective clone (N-MoPn), and a keyhole limpet hemocyanin (KLH)-specific cell line (KLH-1), T cells were labeled with the fluorescent dye PKH-26, a doptively transferred into Chlamydia-infected mice, and monitored at differ ent time points throughout the course of a genital infection, We found that clones P-MoPn and N-MoPn migrated to similar extents to the genital tract and in significantly greater numbers than the KLH-specific T-cell line. Bot h clones and the KLH-1 line expressed similar levels of the adhesion molecu les alpha 4, beta 1, CD44, and CD11a, However, clones P-MoPn and N-MoPn exp ressed higher levels of the mucosal homing receptor, alpha 4 beta 7, Also, clones P-MoPn and N-MoPn but not the KLH-1 line migrated to the mesenteric lymph node, suggesting a mucosal recirculation pattern, Moreover, blocking alpha 4 beta 7 adhesion interaction in vivo significantly reduced the recru itment of P-MoPn but not KLH-1 to the genital tract, These findings show th at the mucosal homing receptor or4P7 is utilized by a subset of CD4 cells d uring migration to the Chlamydia-infected genital tract.