The objective of the LARGO Study protocol is to collect peripheral blood samples, select associated lung biopsy pathology slides, and clinical data from lung transplant recipients to perform molecular analyses in association with the study endpoints. The primary objective is to use gene expression profiling of peripheral blood mononuclear cells to differentiate between the absence and presence of acute cellular rejection. The secondary objectives are to use other genomic and proteomic technologies to analyze RNA and protein in blood samples in relation to related clinical conditions. The overall goal is to apply novel molecular insights in the development of non-invasive molecular diagnostic tests for lung transplantation.