National Jewish Health Advanced Diagnostic Laboratories now offers testing for anti-GMCSF autoantibodies. These autoantibodies have been found to be associated with autoimmune pulmonary alveolar proteinosis (PAP). Detection of these autoantibodies in patients’ serum provides additional evidence to support the diagnosis of PAP. Monitoring levels of anti-GMCSF autoantibodies is of utility in the management of PAP patients on GMCSF therapy. In addition, anti-GMCSF autoantibodies have found to be associated with treatment refractory, chronic bacterial and fungal infections (e.g.; Cryptococcus and Nocardia spp.). Evaluation of patients with such infections for the presence of anti-GMCSF autoantibodies may be of utility in directing therapy towards immunomodulation or cytokine supplementation.