Topical zinc sulfate augmentation of human delayed type skin test response

The ability of topical zinc sulfate to augment the cutaneous delayed hypersensitivity response to Candida antigen was evaluated in 47 adults (15 controls and 32 hospitalized patients). On each adult subject, intradermal standard Candida extract was administered to each forearm followed immediately by topical application of 10% zinc sulfate in Aquaphor® ointment on one arm and Aquaphor® alone on the other arm. The reaction size was assessed in a single blinded manner. Of the 24 subjects who reached positively to Candida antigen, a significantly larger (p < 0.01) number of individuals showed an augmented cutaneous delayed hypersensitivity response in the arm on which the topical zinc sulfate had been applied. However, when patients were stratified by plasma zinc concentrations, only the normal plasma zinc patient group demonstrated a statistical augmentation. Possible mechanisms and selectivity of this observed effect are discussed. These findings suggest a role for topical zinc application to augment cutaneous immune responsiveness.