[Influence of antibodies on the phagocytosis of Klebsiella pneumoniae by alveolar macrophages (author's transl)].

Phagocytosis of Klebsiella pneumoniae by alveolar macrophages of guinea pigs was investigated. Lavage of guinea pig lungs yielded a cell suspension of approximately 85% alveolar macrophages. The remaining cells were predominantly lymphocytes and a few polymorphonuclear leucocytes. After incubation for 5 hours at 37 degrees C the macrophages adhered to the glass surface whereas leucocytes could be washed away. This resulted in a pure culture of macrophages containing 95-98% living cells. Specific antibodies to phenol-water extracts of K. pneumoniae were induced in rabbits. These antisera increased the rate of uptake of the bacteria by macrophages at least 35-fold as compared to macrophages without added antiserum. Preimmunization sera of rabbits also increased the uptake of bacteria by macrophages but by far less than hyperimmune sera. A very sensitive Enzyme-Immuno-Assay (ELISA) for detection of antibodies to the phenol-water extracts of K. pneumoniae was developed. Low levels of antibodies were demonstrated in the pre-immunization sera of rabbits by ELISA but not by the tube agglutination test. These low antibody titers could explain the increased uptake of the bacteria by alveolar macrophages in the presence of preimmunization sera. The influence of complement components on phagocytosis in our sera was small and was therefore not studied in any detail.