[The influence of short-term lead exposure on the bacterial clearance of the lung (author's transl)].

Abstract

The experiments describe the effects of short-term application of low concentrations of lead on the elimination of bacteria in the lungs of laboratory animals. On five subsequent days over a period of three weeks female mice of the NMRI strain were exposed for one and three hours, respectively, to a lead aerosol (mean concentration 13,14 micrograms/m3 lead chloride). Then the animals inhaled FITC labeled non pathogenic bacteria of the species Serratia marcescens. The lungs of the animals examined were analyzed for: a) free fluorescent bacteria in the pulmonary tissue, in the alveoles, bronchioles and bronchi; b) phagocytising alveolar macrophages; c) non-phagocytising alveolar macrophages. The following results have been established: 1. Under the given test conditions a three hour inhalation of lead chloride induces a significant reduction in the elimination of the bacteria. A one hour inhalation causes differences between the mean values of the test group and a control group on nearly all the days of experiments. On the 10th, 13th and 14th day of inhalation a signifcant difference between both groups could be established. The number of bacteria fluctuates largely from one day of test to the next, including a weekly rhythm. 2. Comparing the test group with the control group with respect to the parameters "phagocytising alveolar macrophages" and "free bacteria" as well, one can notice for the one hour lead chloride inhalation particularly high numbers obtained on weekends. The number of phagocytising alveolar macrophages tends to increase after a one hour lead chloride inhalation period during the third week of the experiment. This indicates a reactive increase of phagocytosis stimulated by the increased uptake of bacteria. Contrary after a three hour inhalation period of lead chloride during the third week from the 11th to the 15th day of testing, no further reactive increase in the number of phagocytising alveolar macrophages can be established. . A comparison of the number of non phagocytising alveolar macrophages did not reveal any differences between the mean values of the test groups for one hour and three hour inhalations compared to the control groups.