Efficiency of interleukin 6 and interferon gamma in the differentiation of invasive pulmonary aspergillosis and pneumocystis pneumonia in pediatric oncology patients

Objective: Invasive pulmonary aspergillosis (IPA) and Pneumocystis pneumonia (PCP) are two types of pulmonary fungal infection that are not easy to differentiate. The purpose of this study was to investigate the role of inflammatory cytokines in the differential diagnosis of IPA and PCP. Methods: A total of 227 pediatric oncology patients diagnosed with acute pneumonia were enrolled. They were divided into three groups: IPA, PCP, and 'others'. The cytokine levels in these groups were compared, including interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-10, IL-6, IL-4, and IL-2. Results: Of the six cytokines, only IL-6 and IFN-gamma levels were elevated in patients with acute pneumonia. IL-6 was comparable between patients with IPA and PCP (52.0 pg/ml vs. 25.8 pg/ml, p = 0.092), while IFN-gamma was much higher in patients with PCP (19.9 pg/ml vs. 8.9 pg/ml, p = 0.001). The accuracy of IL-6 and the ratio of IL-6/IFN-gamma in predicting IPA were 69.0% and 72.0%, respectively, while the accuracy of IFN-gamma to predict PCP was 67.2%. IL-6 > 140 pg/ml and IL-6/IFN-gamma > 9.0 presented specificities of 90% in predicting IPA, while IFN-gamma > 40 pg/ml presented specificity of 90% in predicting PCP. Conclusions: IL-6 is predominantly elevated in IPA, while IFN-gamma is significantly increased in PCP. These are helpful tools for the differential diagnosis of IPA and PCP. (C) 2016 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.