DIFFERENTIAL CELL COUNT AND LYMPHOCYTE SUBSETS IN BRONCHOALVEOLAR LAVAGE DURING PNEUMONIA WITH AND WITHOUT PERIPHERAL NEUTROPENIA

One hundred immunocompromised HIV negative patients with microbiologic ally positive pneumonia underwent bronchoalveolar lavage (BAL) studies . Thirty cases showed peripheral neutropenia (<1000 neutrophils/mu L), (1) 70 did not. The total cell number in BAL, the differential cell co unts, and the lymphocyte subsets (CD4, CD8, CD19, CD57) were measured. Patients with pneumonia and normal or elevated peripheral neutrophils had a significantly increased total number of cells in BAL compared t o patients with peripheral neutropenia (3,2 +/- 2 vs 1,3 +/- 0,6 x 10( 5) cells/ml(2) lavage fluid, p < 0.01). Ninety percent of the BAL diff erential cell counts obtained in patients exceeding 1000 neutrophils/m u L showed a lymphocytic and/or neutrophilic alveolitis, whereas only 54% of patients with peripheral neutropenia displayed abnormal counts (p < 0.01). Yet the typical pattern of neutrophilic alveolitis was fou nd more often for peripheral neutrophil counts over 1000/mu L with hig h significance (p < 0.0001). Abnormal BAL cell patterns for neutropeni c patients uniformly showed a lymphocytic alveolitis, only 10% additio nally conformed with the pattern of neutrophilic alveolitis. Patients with pneumonia with and without peripheral neutropenia had similar fin dings in BAL lymphocyte subsets and exhibited a reduced CD4/CD8 ratio compared to controls (p < 0.05). The high susceptibility of severe neu tropenic patients to pulmonary, especially fungal infections may be ex plained by the local lack of neutrophils.