Bitient Selection

Patients were prospectively enrolled in our study if they met each of the following criteria: (1) age >35 years; (2) nodular density <4 cm in diameter on chest roentgenogram; (3) no history of immuno­compromise; (4) already scheduled to undergo fiberoptic bronchos­copy as part of their evaluation; and (5) they gave oral consent, as specified by our Institutional Review Board, to participate in this protocol.

Bronchoalveolar Lavage

The segment or segments of lung thought to contain the nodule (based on fluoroscopic guidance) were lavaged with 60 ml of lactated Ringers solution in 20-ml aliquots. The lavage collection apparatus was changed and the bronchoscope was rinsed before a similar lavage was performed on the contralateral lung. Samples were centrifuged at 500 g for ten minutes and the immunoglobulin- containing supernatant was decanted and stored at — 20°C until measurements were made.

Assays

Albumin was measured by standard nephrometric techniques. Secretory IgA was measured by double antibody radioimmunoas­say.10 All assays were performed on the same day in the same laboratory by an investigator (H.A.H.) who was blinded as to the source of the samples. Results were expressed either as the absolute concentration of slgA in micrograms per milliliter and “corrected” (slgA) ([sIgA]/[albumin]) to remove variation due to dilutional factors.

Follow-up and Clinical Correlation

Patients were followed up for one year and were eventually found to have lung cancer (N = 8), noncancerous lung lesions (N = 5), or an undiagnosed process (N = 1). The last patient was a 55-year-old woman who had a 40 pack/year smoking history and a 1.5-cm nodule in the right upper lobe. She also had electromyographic evidence of motor neuron disease of indeterminate cause. Bronchoscopy showed normal airways and brushings, washings, and biopsy speci­men from the right upper lobe were all negative for cancer as were findings from a transthoracic needle biopsy done two months later. She died of progressive respiratory failure six months after bron­choscopy and autopsy requests were denied. We included her in our “noncancer” group due to our inability to diagnose cancer despite multiple attempts. canadian pharmacy viagra

Statistics

Secretory IgA concentrations, both absolute and corrected, were transformed to the log scale for greater symmetry and then were analyzed by Students t test for comparing cancerous and noncan­cerous patients, and by the paired t test for comparing cancerous and noncancerous lungs of the cancer patients.