title: The role of interleukin-4 in ultraviolet B light-induced immunosuppression.
abstract: Prolonged exposure to ultraviolet light (UV) is known to lead to premature skin ageing, increased incidence of cataract and a high risk of developing skin cancers. UV-B irradiation, even if given as a single suberythemal dose, suppresses some immune responses, possibly reducing the production of T helper (Th) 1 cytokines [interleukin (IL)-2 and interferon-gamma] and augmenting Th2 cytokines (IL-4, IL-5 and IL-10) in mice. We investigated the role of IL-4 in UV-B induced immunomodulation using IL-4 knockout (IL-4 -/-) mice and the parent strain Bb129. Suberythemal UV-B irradiation (1440 J/m2) led to a reduction in the density and antigen presenting ability of Langerhans' cells in the epidermis of both normal and IL-4 -/- mice. Exposure also induced an accumulation of CD4+ and CD8+ lymphocytes as well as dendritic cells in the lymph nodes draining the irradiated site in both strains. The proliferation of lymph node cells in response to the mitogen concanavalin A was enhanced in the IL-4 -/- mice compared with the parent strain. Following UV-B exposure, this proliferation was increased in lymph node cells of parent mice but was significantly suppressed in the IL-4 -/- mice. The contact hypersensitivity (CH) response to oxazolone was suppressed to the same extent by UV-B irradiation in both strains. In the parent mice, infected with herpes simplex virus (HSV) following UV-B exposure and challenged subsequently with inactivated virus, the delayed hypersensitivity (DH) response was suppressed by about 50% compared with unirradiated mice; no such suppression in DH occurred in irradiated IL-4 -/- mice infected with HSV. Thus, IL-4 may be an important mediator of the UV-B-induced suppression in DH but not in CH, where other cytokines may be involved or may compensate for the lack of IL-4.
authors.affiliation: Department of Medical Microbiology, University of Edinburgh Medical School, UK.
authors.forename: A A
authors.initials: AA
authors.lastname: el-Ghorr
authors.forename: M
authors.initials: M
authors.lastname: Norval
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000528:radiation effects; D002455:Cell Division / Q000276:immunology; D003877:Dermatitis, Contact / Q000276:immunology; D005260:Female; D006968:Hypersensitivity, Delayed / Q000276:immunology; D007108:Immune Tolerance / Q000528:radiation effects*; D015847:Interleukin-4 / Q000276:immunology*; D007801:Langerhans Cells / Q000528:radiation effects; D008198:Lymph Nodes / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D016176:T-Lymphocyte Subsets / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D015847:Interleukin-4