Background: No specific data are available in the literature on the bronchoalveolar Lavage (BAL) findings of Legionella pneumophila pneumonia. We report on the cytological and immunophenotypical BAL data of three immunocompetent patients with severe community-acquired pneumonia due to L. pneumophila serogroup 1.
Methods: Retrospective chart review. The microbiologial diagnosis was obtained by BAL culture or/and urinary antigen assay.
Results: All patients presented with high-grade fever, bilateral chest infiltrates and severe respiratory failure requiring ventilatory support. The cytological BAL pattern at presentation showed in all patients the association of a marked neutrophilia with a variable but remarkable percentage of lymphoblasts. Increased levels of activated T-Lymphocytes (both HLA-DR + and CD25 + cells) and, in 2 out of 3 patients, of T-cells bearing the gamma/delta T-cell receptor were the main immunophenotypical findings on flow cytometric analysis.
Conclusions: We suggest that the association of lymphoblasts with a marked neutrophilia in BAL fluid of patients with a clinical-radiological setting compatible with acute pneumonia should suggest L. pneumophila as a possible etiologic agent.