title: Impaired primary T cell responses in L-selectin-deficient mice.
abstract: L-selectin is a homing receptor that mediates the selective attachment of leukocytes to specialized high endothelial venules. To study the potential role of L-selectin in immune responses in intact mice, we generated L-selectin-deficient mice by gene targeting. L-selectin-deficient mice are defective in cutaneous delayed-type hypersensitivity (DTH) responses when tested after conventional intervals of immunization (4 d). Primary T cell proliferative responses and cytokine production (interleukin [IL] 2, IL-4, and interferon gamma) were also compromised when tested after 5 d of immunization, indicating that L-selectin is important for the immune response to antigens. In contrast, after more prolonged immunization protocols (9 d), normal responses were observed, suggesting that L-selectin-independent compensatory mechanisms exist. Interestingly, humoral responses of L-selectin-deficient mice to keyhole limpet hemocyanin are indistinguishable from wild-type control mice, implying that L-selectin plays no rate-limiting role in T cell help of B cell function. Thus, our results suggest that L-selectin plays an important role in the generation of primary T cell responses but may not be essential for humoral and memory T cell responses. L-selectin does not appear to be rate limiting for the events leading to antigen-driven neutrophil recruitment, since normal DTH responses are obtained at late time points after immunization.
authors.affiliation: Howard Hughes Medical Institute, Section of Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: I S
authors.initials: IS
authors.lastname: Grewal
authors.forename: G P
authors.initials: GP
authors.lastname: Geba
authors.forename: R A
authors.initials: RA
authors.lastname: Flavell
mesh_terms: D000818:Animals; D000917:Antibody Formation; D016207:Cytokines / Q000096:biosynthesis*; D003877:Dermatitis, Contact; D006433:Hemocyanins / Q000276:immunology; D006968:Hypersensitivity, Delayed; D007114:Immunization; D007156:Immunologic Memory; D019041:L-Selectin / Q000235:genetics / Q000378:metabolism*; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008817:Mice, Mutant Strains; D009504:Neutrophils / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D016207:Cytokines; D019041:L-Selectin; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin