A standard method for DNCB sensitization testing in patients with neoplasms

Abstract

A method is described for the quantification of the DNCB sensitization-test. Sensitization was performed by epicutaneous application of 2 mg of the substance. Fourteen days later, challenges were performed by patch testing with 30, 10, and 3 μg of DNCB in acetone. In this way erroneous readings (by toxic skin responses) may be avoided. The reactions were graded according to common practice in clinical allergology (1–4+). The sum of the reactions on the three concentrations was taken as a measure of skin reactivity (designated as DNCB-score). Three groups of people were assayed. Of 48 controls, all but 1 (98%) showed positive reactions. The average DNCB-scores of the melanoma and Hodgkin's patients were significantly lower than the controls'. Of 66 patients with malignant melanoma (45 of them had clinically localized tumors), only 76% developed a contact allergic reaction. Of 8 patients with malignant Hodgkin's disease, 2 could be sensitized. Further analysis revealed that in both the control and the melanoma group, DNCB-reactivity decreases with age. To ascertain the chance of cross-sensitization, tests were done with chemically-related components. Two out of 49 persons with a contact hypersensitivity to DNCB developed positive tests to related chemicals, which indicates that cross-sensitization is a risk of the DNCB-test.