LAUSR

A cellular rejection (ACR) represents one of the most common lung transplant complications affecting 29% of patients according to the most recent registry report by the International Society for Heart and Lung Transplantation. Although ACR is most prevalent in the first year after transplantation, its presence significantly increases the risk of subsequent development of chronic lung allograft dysfunction, most notably bronchiolitis obliterans syndrome. Acute cellular rejection can occur in either asymptomatic or symptomatic patients and frequently cannot be distinguished from infection. Therefore, the gold standard for diagnosis and classification of ACR has been histopathologic analysis of lung tissue obtained by transbronchial biopsy (TBB) according to the recommended guidelines. Inmost studies, the sensitivity of TBB for diagnosis of ACR ranges from 72% to 84%. In addition to inadequate tissue sampling and the risks posed by bronchoscopy and biopsy, there is a potential for high degree of interobserver variability and limited reproducibility with TBB thatmight lead to undertreatment or overtreatment of ACR. Probe-based confocal laser endomicroscopy (pCLE) is a novel bronchoscopic technique that uses a laser beam to generate autofluorescence of elastin and macrophages at the alveolar level, thereby allowing visualization of alveolar structure, blood vessels, and intra-alveolar macrophages. The fluorescent signal is recorded at the spatial resolution of 3 μm and analyzed with the assistance of computer software. In addition to capturing still images, this imaging technique can produce sequential video fragments that can be analyzed in real-time by a bronchoscopist. Previously, Yserbit et al have found in their retrospective study that pCLE demonstrated sensitivity and specificity of 96% and 83%when using the combination of 3 pCLE criteria for the diagnosis of ACR. These pCLE criteria included autofluorescent