Prospective Trial of Rituximab for Primary Pulmonary Alveolar Proteinosis

Inclusion Criteria: * Diagnosis of primary PAP (new or chronic) with presence of anti-GM-CSF antibody * Moderately symptomatic disease with PaO2 \<70 on room air and on less than 6 L/min oxygen * Able to give written informed consent and comply with the requirements of the study * Adequate renal and liver function * Negative serum pregnancy test (for women of child bearing age) and on acceptable birth control during and after study completion Exclusion Criteria: * Severe PAP and requires in-patient care and more urgent therapy with bilateral whole lung lavage * Treatment with any investigational agent within 4 weeks of screening * History of severe allergic or anaphylactic reactions to humanized or murine monoclonal antibodies * History of HIV, recurrent significant infection or recurrent bacterial infections * Known active bacterial, viral, fungal, mycobacterial, or other infection * Ongoing use of high dose steroids (\>10mg/day) or unstable steroid dose * Significant cardiac or pulmonary disease or blood disorder