title: Study of persistence and loss of patch test reactions to dichromate and cobalt.
abstract: Hyposensitization is a poorly understood phenomenon that refers to the conversion from a positive to a negative (or less positive) patch test. We studied 180 cement workers with contact dermatitis, who originally had a total of 163 positive patch test reactions to potassium dichromate and 98 positive reactions to cobalt chloride. They were patch tested a 2nd time after 2-6 years. On the 2nd patch test to dichromate, 103 (63%) remained positive, while reactivity decreased in 33 (20%) and 27 (17%) had become non-reactive. Cobalt sensitivity persisted in 47%, diminished in 13%, and 40% of the patch tests became non-reactive. In 10 patients with persistent patch test reactions and 10 matched patients with diminished reactions or loss of reactivity, circulating T-cell responses to dichromate and cobalt were studied in vivo. Circulating T cells that proliferated only to specific contact allergens were isolated and in all patients they were primarily CD4+. However, in patients with persistent reactions, they were CD4+ CD45RA+ (suppressor - inducer cells). These differences support an immunologic basis for hyposensitization.
authors.affiliation: University of Athens Department of Dermatology, A. Sygros Hospital, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Katsarou
authors.forename: C
authors.initials: C
authors.lastname: Baxevanis
authors.forename: M
authors.initials: M
authors.lastname: Armenaka
authors.forename: M
authors.initials: M
authors.lastname: Volonakis
authors.forename: A
authors.initials: A
authors.lastname: Balamotis
authors.forename: M
authors.initials: M
authors.lastname: Papamihail
mesh_terms: D000328:Adult; D003035:Cobalt / Q000009:adverse effects*; D003252:Construction Materials / Q000009:adverse effects; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis* / Q000276:immunology; D009783:Dermatitis, Occupational / Q000175:diagnosis* / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D010328:Patch Tests; D011192:Potassium Dichromate / Q000009:adverse effects*; D016176:T-Lymphocyte Subsets
chemical_list: D003035:Cobalt; C018021:cobaltous chloride; D011192:Potassium Dichromate