Increased IgE-antibodies to Staphylococcus aureus enterotoxins in patients with COPD

Recent evidence suggests that Staphylococcus aureus enterotoxins (SAEs) could modify airway disease by acting as superantigens, an immune response that can be monitored by detection of IgE antibodies to SAEs. We studied the expression of total IgE and specific IgE to SAEs using the Uni-CAP system in healthy controls, smokers without COPD and COPD patients. Only 1/10 controls (10%) and 1/16 smokers (6.3%) had IgE to SAEs compared to 7/18 patients with stable COPD (38.9%) and 21/54 patients with exacerbated COPD (38.9%). The IgE levels to SAEs of the patients with stable COPD (0.18 [0.05-26.2]kUA/l) and the patients with exacerbated COPD (0.09 [0.05-18.6]kUA/l) were significantly higher than those of smokers (n = 16; 0.05 [0.05-0.82]kUA/l) and controls (n = 11; 0.05 [0.05 0.9]kUA/l, P<0.05). IgE to SAEs decreased significantly in the exacerbated patients during hospitalization (0.13 [0.05-18.3] vs. 0.05 [0.05-11]kUA/l, P<0.001) going along with a significant increase in FEV1 (38.1 [16.9-79.5] vs. 51.6 [15-80]%predicted, P<0.001). Similarly to severe asthma, we found significantly elevated IgE to SAE in COPD patients. Our data for the first time suggest differences between healthy subjects, smokers and patients with established COPD regarding the role of bacterial products and point to a possible disease modifying role of SAEs.