A quantitative and qualitative study of blood monocytes in smokers

The effect of cigarette smoking on blood monocyte count and selected functions of isolated blood monocytes was studied in 82 subjects free of intercurrent or chronic disease, 41 smokers and 41 non-smokers. Total leukocyte counts and monocyte counts were higher in smokers than in non-smokers. In vitro functional studies of spontaneous migration, chemotactic responsiveness and phagocytosis showed no correlation with smoking habits. However, intracellular killing of Candida albicans was significantly lower in blood monocytes of smokers as compared to non-smokers. Since blood monocytes are the precursors of tissue macrophages the defective microbicidal function may represent an additional pathogenic factor in the diminished host defence observed in smokers.