New advances in contact dermatitis

The effect of race and ethnicity on patch test results

BACKGROUND

Allergic contact dermatitis is a condition that may be affected by differences in genetic and environmental factors. Race and ethnicity are possible examples of the former.

OBJECTIVE

The objective of this study was to examine the differences in patch test results between white and black individuals tested by the members of the North American Contact Dermatitis Group from July 1, 1992, to June 30, 1998.

METHODS

Patients evaluated in our patch test clinics were exposed to a standardized patch testing technique involving a standard series of 41 allergens in total. The standard series we used varied over the 6 years of the study in 2-year cycles. The series was the same at all centers during each of these 2-year cycles: 1992-94, 1994-96, and 1996-98. Over a 6-year period, our group tested 9624 patients. Of those individuals, 8610 (89.5%) were white and 1014 (10.5%) were black.

RESULTS

Allergic contact dermatitis and irritant contact dermatitis were the final diagnoses assigned by the investigators to individuals of the 2 races: 49% and 16%, respectively, for the white patients and 46% and 15%, respectively, for the black patients. In at least one of the three 2-year periods, testing in white patients revealed higher rates of sensitization to formaldehyde, glutaraldehyde, and a number of the formaldehyde-releasing preservatives, as well as lanolin, epoxy resin, thioureas, and balsam of Peru. Black patients exhibited higher rates of sensitization to para-phenylenediamine, cobalt chloride, thioureas, and p-tert-butylphenol formaldehyde resin in at least one of the 2-year periods.

CONCLUSION

In this test population, we found no differences in the overall response rate to allergens. There were some differences between white and black patients in their response to specific allergens. These differences, although possibly related to genetic factors based on race, are more likely related to differences in allergen exposure determined by ethnicity.

Acid hydrolases in blister fluid. 6. Photocontact and contact allergic skin reactions

Increased acid hydrolase activity has been demonstrated in the fluid from experimental suction blisters raised on the sites of contact or photocontact allergic skin reactions. The magnitude of the increases correlated well with the intensity of the reactions. The enzymes appeared after latent periods of 10 h for vesicular reactions, 15 h for papular reactions and 24 h for erythematous responses. The present observations are very similar to those reported following UV-B; thus our previous conclusions regarding the role of lysosomal hydrolases in UVR erythema may be generalized to include other forms of cutaneous inflammation.