Interferon-gamma production in atopic dermatitis: a role for prostaglandins?

Peripheral blood mononuclear cells (PBMC) from patients with atopic dermatitis (AD) have a reduced capacity to produce interferon-gamma (IFN-gamma) in vitro, in response to phytohaemagglutinin (PHA) when compared to healthy non-atopic controls. This defect appears to correlate closely with the severity of AD at the time of sampling, with less IFN-gamma being produced by cells from patients with more severe disease. Enhanced production of IFN-gamma was observed as the patients clinical symptoms improved. In addition, IFN-gamma production could be increased by either pre-culturing the cells for 3 days prior to PHA stimulation or by addition of indomethacin to the culture medium. These observations suggest that the mechanism of reduced IFN-gamma production in AD is unlikely to be due to an intrinsic cellular defect. The possibility that prostaglandins mediate the suppressed production of IFN-gamma in AD was supported by demonstrating that exogenous prostaglandin E2 (PGE2) inhibited IFN-gamma production in PHA-stimulated PBMC. PGE2 at a physiological concentration (10(-9) M) was also shown to enhance interleukin 4 induction of IgE synthesis by PBMC cultures. Our data suggest that alterations in prostaglandin metabolism play a crucial role in the pathogenesis of AD by inhibiting the production of IFN-gamma.