Contact sensitivity to dinitrochlorobenzene is impaired in atopic subjects. Controversy revisited

If there is a primary dysfunction of the immune system in atopic eczema it might be reflected in altered capacity to generate delayed-type hypersensitivity. Therefore, the dose-response relationships for contact sensitization were determined for 22 patients (10 men) with minimal atopic eczema and compared with those from 27 nonatopic, healthy control subjects (12 men). Sensitization was induced with 30 micrograms of dinitrochlorobenzene applied to the thigh. Four weeks later the subjects were challenged with three doses of dinitrochlorobenzene (8.8, 12.5, and 17.7 micrograms), and responses were quantified with calipers as change in skinfold thickness at 48 hours. Atopic patients were significantly less responsive with smaller reactions at all challenge doses and a flatter challenge dose-response curve than that for control subjects. Thus, proper quantitative comparisons have shown that subjects with minimal atopic eczema do not mount a normal contact hypersensitivity response. However, it is not clear whether this is a consequence of the atopic state per se or is related to the presence of even a minor degree of eczema.