title: Preliminary identification of a low molecular weight serological mediator in chronic idiopathic urticaria.
abstract: Sixteen patients with chronic idiopathic urticaria were skin tested with their own serum, IO with autologous plasma and five with serum that had been heated to 56 degrees C to inactivate complement. Eight showed a weal and flare response to whole serum, four to plasma and five to heat-treated serum. All serum-positive patients showed the same response to their own plasma and to heated serum, indicating that the mediator concerned is not generated by clotting and is not dependent on a functioning complement pathway. Three control subjects were negative to autologous serum, plasma and heated serum. Local tachyphylaxis was demonstrated in five serum-positive patients on reinjection of the same site with autologous serum on 3 consecutive days. This raises the possibility that the serological mediator may be acting by mast cell degranulation or directly on receptors in blood vessels and that repeated injections could induce a change in the number of receptors. Passage of whole autologous serum from four serum-positive patients through ultrafiltration membranes showed that fractions with a molecular weight of less than 30,000 daltons were still able to produce a positive skin test response, but those less than 1000 daltons were not. All serum fractions from two serum-negative patients and three normal controls were negative. Whole autologous serum from five serum-positive patients and two control subjects were separated by column chromatography. On skin testing with pooled fractions, the greatest response was produced by fractions of 10,000-15,000 daltons in the serum-positive patients, but there was no response in the controls.
authors.affiliation: Department of Dermatology, General Hospital, Birmingham, U.K.
authors.forename: C E
authors.initials: CE
authors.lastname: Grattan
authors.forename: C G
authors.initials: CG
authors.lastname: Hamon
authors.forename: M A
authors.initials: MA
authors.lastname: Cowan
authors.forename: R J
authors.initials: RJ
authors.lastname: Leeming
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001769:Blood; D002908:Chronic Disease; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D010949:Plasma; D012882:Skin Tests; D014581:Urticaria / Q000097:blood* / Q000276:immunology