Altered expression of IgG and complement receptors indicates a significant role of phagocytes in atopic dermatitis

Strict dietary precautions against allergic sensitization may benefit a group of predisposed children.

To develop new strategies for identifying these children, a better understanding of the processes that initiate sensitization and regulate and perpetuate the inflammatory response is needed.

We measured the expression of the receptors for the constant (Fc) region of IgG (Fc gamma RI, Fc gamma RII, and Fc gamma RIII) and that for the complement fragments C3b and C3bi (CR1 and CR3) in neutrophils and monocytes from 39 children with atopic dermatitis, 17 disease control patients with acute infections, and 17 healthy control subjects. The capacity of phagocytes to produce reactive oxygen species was also determined. To find the best way of discriminating the patients with atopic dermatitis from control subjects, a stepwise logistic binary regression model was made.

The stepwise logistic regression analysis was based on differences in individual receptor expression between the study groups. Because acute infections strongly affected receptor expression in both neutrophils and monocytes, to avoid diagnostic bias, children with acute infections were excluded from the analysis. The combination of the receptors CR1 in neutrophils and Fc gamma RI and Fc gamma RII in monocytes was the best indicator of atopic dermatitis. A significant correlation between the expression of CR1 in neutrophils and in monocytes, as well as reactive oxygen species production of phagocytes, and the severity of the eczema was detected.

These results suggest that a distinct receptor profile of phagocytic cells can be characterized in patients with atopic dermatitis, providing a new direction to the search for early identification of children predisposed to allergic sensitization.