Interaction between the Legionnaires' Disease Bacterium (Legionella pneumophila) and Human Alveolar Macrophages Influence of Antibody, Lymphokines,

Abstract

Abstract. We have studied the interaction between virulent Legionella pneumophila and human alveolar macrophages, the resident phagocytes at the site of infection in Legionnaires ' disease. L. pneumophila multiplied 2.5-5 logs within 3 d, as measured by colony forming units, when incubated with freshly explanted alveolar macrophages in monolayer culture. At the peak of bacterial multiplication, the alveolar macrophage monolayers were destroyed. L. pneumophila multiplied more rapidly in 4-d-old than in freshly explanted alveolar macrophages. Inside alveolar macrophages, L. pneumophila were located within membrane-bound vacuoles whose cytoplasmic sides were studded with ribosomes. Alveolar macrophages that were incubated with concanavalin A (Con A) stimulated human mononuclea