Arginase I Levels Are Decreased In Pediatric Patients with Atopic Dermatitis

Background: Serum arginase levels have been shown to be elevated in conditions such as trauma, solid tumors, pregnancy, and asthma. In the immunosuppressive states of pregnancy and tumors, it has been shown that increased levels of arginase result in a low L-arginine environment which leads to T-cell suppression through downregulation of CD3z chain expression. Atopic dermatitis, a well-known state of pathologic inflammation and T-cell activation, has not been previously studied in relation to arginase activity and T cell function.

Methods: In this pilot study, arginase activity levels in 15 pediatric patients with atopic dermatitis were compared to 6 controls to determine if a link between arginase and atopic dermatitis exists.

Results: Arginase activity was found to be consistently decreased in both the granulocytes as well as in the plasma of atopic dermatitis patients as compared to controls, coupled with a trend of higher L-arginine plasma levels in the atopic dermatitis patients. In addition, the lower levels of arginase were not found to be due to release of granule contents, but likely due to decreased production or increased degradation. 

Conclusions: We postulate a new mechanism for the chronic inflammatory state of atopic dermatitis which is based on the loss of suppression of T cell function through the arginine pathway, allowing for an unregulated state of T cell activation.