title: The role of platelets in leukocyte recruitment in chronic contact hypersensitivity induced by repeated elicitation.
abstract: Platelets have been shown to be important in inflammation, but their role in chronic allergic dermatitis remains unclear. To investigate the role of platelets in a mouse model of chronic contact hypersensitivity induced by repeated elicitation, mice were sensitized and repeatedly elicited in ears with hapten, with or without platelet depletion, by administering antiplatelet antibody or busulfan. Ear thickness, leukocyte infiltration, serum IgE, and scratching behavior significantly decreased in thrombocytopenic mice. cDNA microarray of ear tissue showed reduced gene expression associated with Th2 lymphocytes. Flow cytometry showed increased P-selectin expression on platelets and an increased number of platelet-leukocyte aggregates in blood of repeatedly elicited mice, compared with sham-sensitized mice. In thrombocytopenic mice, inflammation was restored by platelet infusion, which was blocked by platelets from P-selectin-deficient mice or by pretreating platelets with anti-P-selectin antibody. Moreover, injection of activated platelet supernatant into ears led to increased leukocyte infiltration, which was blocked by pretreating platelets with antiplatelet compounds or neutralizing several chemokines in the platelet supernatant. These results suggest that platelets induce leukocyte recruitment into skin by forming platelet-leukocyte aggregates via P-selectin in blood and secreting chemokines at inflamed sites. Therefore, controlling platelet activity may be useful for treatment of chronic allergic dermatitis.
authors.affiliation: Department of Dermatology, Kyoto Prefectural University of Medicine Graduate School of Medical Science, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
authors.forename: Risa
authors.initials: R
authors.lastname: Tamagawa-Mineoka
authors.forename: Norito
authors.initials: N
authors.lastname: Katoh
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Ueda
authors.forename: Hideya
authors.initials: H
authors.lastname: Takenaka
authors.forename: Masakazu
authors.initials: M
authors.lastname: Kita
authors.forename: Saburo
authors.initials: S
authors.lastname: Kishimoto
mesh_terms: D000818:Animals; D000906:Antibodies / Q000008:administration & dosage / Q000276:immunology; D001792:Blood Platelets / Q000276:immunology*; D002066:Busulfan / Q000008:administration & dosage / Q000276:immunology; D003877:Dermatitis, Contact / Q000097:blood / Q000276:immunology; D004423:Ear / Q000033:anatomy & histology / Q000473:pathology; D020869:Gene Expression Profiling; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000276:immunology; D007962:Leukocytes / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D019007:P-Selectin / Q000235:genetics / Q000378:metabolism; D012867:Skin / Q000166:cytology / Q000276:immunology; D013921:Thrombocytopenia / Q000378:metabolism
chemical_list: D000906:Antibodies; D007166:Immunosuppressive Agents; D019007:P-Selectin; D002066:Busulfan