title: Lymphocyte alterations after prolonged sunlight exposure.
abstract: BACKGROUND
  It has been suggested that prolonged exposure to sunlight may induce systemic or local immune alterations, which may facilitate the development of skin cancer and, perhaps, non-Hodgkin's lymphona. The effects of prolonged sunlight exposure on peripheral blood cells were studied.
  
  
  METHODS
  Leukocytes and lymphocyte subpopulations of 12 volunteers aged 10-45 were investigated before and after a 3-week summer holiday in seaside resorts in Greece. Lymphocyte phenotypes were estimated using monoclonal antibodies and flow cytometry.
  
  
  RESULTS
  There were no significant differences with respect to total numbers of T cells, T-helper/inducer, T-suppressor/cytotoxic, B cells or HLA-Dr+ cells. However, we have found evidence of lymphocyte stimulation, reflected in an increase in cells expressing the interleukin-2 receptor (IL-2R) and, more specifically, an increase in the T cells expressing IL-2R and HLA-Dr antigens. An increase in natural killer cells has also been noticed.
  
  
  CONCLUSIONS
  These findings suggest that prolonged intense exposure to sunlight may be associated with immunostimulation, rather than immunosuppression.
authors.affiliation: Department of Immunology and Histocompatibility, Aghia Sophia Children's Hospital, Athens, Greece.
authors.forename: M
authors.initials: M
authors.lastname: Kanariou
authors.forename: E
authors.initials: E
authors.lastname: Petridou
authors.forename: E
authors.initials: E
authors.lastname: Vrachnou
authors.forename: D
authors.initials: D
authors.lastname: Trichopoulos
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D006801:Humans; D007958:Leukocyte Count; D008213:Lymphocyte Activation / Q000528:radiation effects*; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology / Q000528:radiation effects*; D008297:Male; D008875:Middle Aged; D013472:Sunlight; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology / Q000528:radiation effects; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000528:radiation effects; D013997:Time Factors; D014466:Ultraviolet Rays