title: In vitro effects of ultraviolet A on histamine release from human basophils.
abstract: BACKGROUND
  As long-wave ultraviolet (UV) radiation penetrates the dermis, connective tissue cellular components and circulating blood cells can be possible targets for solar UVA. Basophils, involved in the effector phase of the inflammatory response, play a part in skin diseases such as chronic urticaria, psoriasis, atopic dermatitis, fixed drug eruption, allergic contact dermatitis, urticaria pigmentosa, systemic sclerosis and bullous pemphigoid.
  
  
  OBJECTIVE
  The evaluation of the in vitro effect of UVA on histamine release from human basophils.
  
  
  METHODS
  Basophils from healthy human volunteers were irradiated, respectively, with UVA at doses of 2.5, 5, 7.5, 10, 20 and 50 J/cm2 and then incubated with an anti-IgE serum. A fluorimetric technique was employed to determine histamine release from samples: (i) incubated with 2% HClO4 (complete lysis of basophils); (ii) irradiated with increasing doses of UVA; and (iii) unirradiated (controls).
  
  
  RESULTS
  Histamine release was: 100% for HClO4 incubated basophils, 30% for unirradiated and anti-IgE incubated cells (controls) and 27%, 24%, 34%, 41%, 60% and 70% for basophils irradiated with UVA doses, respectively, of 2.5, 5, 7.5, 10, 20 and 50 J/cm2 and incubated with anti-IgE. Histamine releasability from irradiated samples was statistically significant (P < 0.05), in comparison with controls, at UVA doses equal to 5, 10, 20 and 50 J/cm2.
  
  
  CONCLUSIONS
  UVA exerts, at least in vitro, a biphasic dose-dependent action on histamine release from human basophils incubated with an anti-IgE serum: at the lowest irradiation doses (< 5 J/cm2) it exerts an inhibitory effect and at the highest doses (> or = 10 J/cm2) histamine release increases significantly.
authors.affiliation: Division of Dermatology, University of Naples Federico II, Via S. Pansini, 5, 80131 Naples, Italy. monfreco@unina.it
authors.forename: G
authors.initials: G
authors.lastname: Monfrecola
authors.forename: A
authors.initials: A
authors.lastname: de Paulis
authors.forename: E
authors.initials: E
authors.lastname: Prizio
authors.forename: I
authors.initials: I
authors.lastname: Russo
authors.forename: M
authors.initials: M
authors.lastname: Carfora
authors.forename: P
authors.initials: P
authors.lastname: Santoianni
authors.forename: G
authors.initials: G
authors.lastname: Marone
mesh_terms: D001491:Basophils / Q000528:radiation effects*; D002478:Cells, Cultured; D006636:Histamine Release / Q000528:radiation effects*; D006801:Humans; D066298:In Vitro Techniques; D011336:Probability; D011829:Radiation Dosage; D012016:Reference Values; D012680:Sensitivity and Specificity; D014466:Ultraviolet Rays