Pulmonary Alveolar Proteinosis

Abstract

Abstract: Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by the accumulation of surfactant phospholipids and proteins in the alveoli (Trapnell et al, N Engl J Med. 2003;349:2527–2539). Less than 500 separate cases of PAP have been reported in the literature from the time of first description in 1958. These reports suggest an annual incidence of 0.36 and prevalence of 3.7 cases per million population (Seymour et al, Am J Respir Crit Care Med. 2002;166:215–235). The clinical course of PAP ranges from spontaneous resolution to death because of superimposed infection or respiratory failure. A number of important milestones mark the key advances in the study of this disease, which have led to an improved classification based on pathogenesis. In the last decade, the serendipitous finding of a lung disease reminiscent of PAP in transgenic granulocyte-macrophage colony-stimulating factor knockout mice (GM-CSF−/−) led to the link between GM-CSF and PAP (Dranoff et al. Science. 1994;264:713–716; Stanley et al. Proc Natl Acad Sci USA. 1994;91:5592–5596). The finding of neutralizing antibodies to GM-CSF suggest an autoimmune basis to idiopathic PAP (Kitamura et al. J Exp Med. 1999;190:875–880). These findings have resulted in innovative treatment approaches to enhance the current standard of care. This review summarizes some of these landmark studies and provides a rationale and plan for investigations that lead to the diagnosis, classification, and management of PAP.