Interleukin-4-positive mast cells are highly associated with the extent of immediate allergic wheal reaction in the skin.

BACKGROUND

In addition to histamine, mast cells contain other potent mediators which can contribute to the allergic wheal reaction in the skin.

METHODS

To study the association of tryptase-, chymase-, and interleukin-4 (IL-4)-positive mast cells with the size of the prick-test wheal reaction, 50 sensitive atopic subjects were prick-tested with the cow-dander allergen on the forearm skin, and the wheal area was measured. A corresponding site of intact healthy-looking skin was biopsied and examined enzyme-histochemically for tryptase and chymase. A double-staining method was used to demonstrate the immunoreactivity of IL-4 and chymase inhibitors (alpha1-proteinase inhibitor and alpha1-antichymotrypsin) in mast cells. The levels of total and cow-specific immunoglobulin E (IgE) were measured in serum.

RESULTS

The number of tryptase- and chymase-positive mast cells or those containing chymase inhibitors revealed no correlation with the wheal reaction. In contrast, both the percentage and the number of IL-4-positive mast cells showed significant positive correlation with the wheal size per se (P<0.0001), as well as with the ratio of the wheal size by cow allergen to that by histamine control (P<0.003). In addition, tryptase-, chymase-, and IL-4-positive mast cells correlated with total IgE, but not with specific IgE, levels, and they showed no relation to the clinical manifestation of atopic disease, asthma or atopic dermatitis.

CONCLUSIONS

The novel finding was that IL-4-positive, but not tryptase- and chymase-positive, mast cells are intimately associated with the extent of the prick-test wheal.