The loss of contact sensitization in man

R. Valsecchi, A. Rossi, A. Bigardi, P. D. Pigatto

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Little is yet known about the duration of contact sensitivity, but frequent exposure of a target to allergen seems to reduce skin reactivity. The aim of this study was to study the persistence of a specific contact sensitivity in 66 patients with alopecia areata, previously sensitized to DNCB (31 patients) and SADBE (35 patients) between 1978-1985. Patch tests were performed with 0.020 ml of different concentrations of DNCB or SADBE in acetone(0.05%, 0.10%, 0.20%, 1%). The results were read in a standardized manner. Of 66 patients, 47 (71%) had positive reactions and 19 (29%) negative. 8 of the 19 negative patients had been treated with DNCB, 11 with SADBE. Approximately 1/3 of the patients previously sensitized had lost their original sensitivity, and this did not seem to be time-dependent. This phenomenon seemed to be clinically correlated because the majority of the patients were from the 'low responders' group. We think that acquired unresponsiveness to topical antigen in man is a possible phenomenon, but that it occurs more rarely than in mice and guinea pigs.

Original languageEnglish
Pages (from-to)183-186
Number of pages4
JournalContact Dermatitis
Issue number3
Publication statusPublished - 1991


  • alopecia areata
  • contact sensitization
  • DNCB
  • loss with time
  • man

ASJC Scopus subject areas

  • Immunology
  • Dermatology
  • Toxicology


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