Contact allergens in shoe leather among patients with foot eczema

Some patients with relapsing foot eczema and a shoe leather allergy, who fail to show positive results with standard series and shoe wear screening tray patch testing, do not respond to the use of hypoallergenic shoe leather. We assume that relevant allergens are present in hypoallergenic shoe leather. We described an experiment to demonstrate the presence of these allergens. Alcoholic extracts were made of green, black and undyed hypoallergenic shoe leather, and the extracts were fractioned by paper chromatography. The resulting chromatograms were cut into 16 equal paper disks and patch tests were performed with extracts and the paper chromatography fractions. Positive reactions were seen to all extracts and to fractions of all types of leather. From analysis of the pattern of positive patch tests we concluded that leather-related allergens (e.g. tanning agent) and dyes were present in hypoallergenic shoe leather. In these cases, alternatives to shoe leather should be sought, for instance wooden or plastic shoes.