Heparin‐binding protein, lysozyme, and inflammatory cytokines in bronchoalveolar lavage fluid as diagnostic tools for pulmonary infection in lung transplanted patients

Stjärne Aspelund, Anna; Hammarström, Helena; Inghammar, Malin; Larsson, Hillevi; Hansson, Lennart; Christensson, Bertil; Påhlman, Lisa I.

Pulmonary infection is a common complication after lung transplantation, and early detection is crucial for outcome. However, the condition can be clinically difficult to diagnose and to distinguish from rejection. The aim of this prospective study was to evaluate heparin‐binding protein (HBP), lysozyme, and the cytokines interleukin (IL)‐1β, IL‐6, IL‐8, IL‐10 and tumor necrosis factor (TNF) in bronchoalveolar lavage fluid (BALF) as potential biomarkers for pulmonary infection in lung‐transplanted patients. One hundred thirteen BALF samples from 29 lung transplant recipients were collected at routine scheduled bronchoscopies at 3 and 6 months, or on clinical indication. Samples were classified into no, possible, probable, or definite infection at the time of sampling. Rejection was defined by biopsy results. HBP, lysozyme, and cytokines were analyzed in BALF and correlated to likelihood of infection and rejection. All biomarkers were significantly increased in BALF during infection, whereas patients with rejection presented low levels that were comparable to noninfection samples. HBP, IL‐1β, and IL‐8 were the best diagnostic markers of infection with area under the receiver‐operating characteristic curve values of 0.88, 0.91, and 0.90, respectively. In conclusion, HBP, IL‐1β, and IL‐8 could be useful diagnostic markers of pulmonary infection in lung‐transplanted patients.