Smoking as a Cause for Mild Chronic Neutrophilia.

Mild chronic neutrofilia is a frequent reason for hematologic consultation and in 70% of the cases there is no identifiable cause.

Objective: to determine if smoking habit could be the etiology for leucocytosis with neutrophilia in smokers with no other pulmonary associated disease.

Materials and Methods: We questioned 300 consecutive blood donors from our institution, elaborating a complete record of smoking habit. Immediately before blood donation an automated complete blood count was performed. Leucocytosis was defined as a white cell count above 11 x 10^9/L, and neutrophilia as a neutrophil count over 7.7 x 10^9/L. All data is stated as mean value ± 1 SD.

Results: we studied 195 (65%) men and 105 (35%) women (n=300). Mean age was 36.5 y.o. (18–69). Fifty-five percent (165/300) smoke or were previous smokers; 8.4% (14/165) of these, did not smoke at the time of this investigation, and only two have quit smoking a year prior to questioning. Mean time of duration of smoking habit was 16.4 years ± 10.6 and the average amount of cigarettes smoked through life (estimated from data referred along different phases of each subject’s history) was 1.26 x 10⁵ ± 1.21 x 10⁵. In the following table results from smokers (previous or actual) vs. non-smokers are compared.

Leucocytosis was present in 37/165 (22.4%) of smokers and in 3/135 (2.2%) of non-smokers (p<0.001) and neutrophilia was noted in 19/165 (11.5%) of smokers and in 2/135 (1.5%) of non-smokers (p<0.001). None of the volunteers had a WBC count over 20 x 10^9/L. A direct association was established for the number of cigarettes smoked and the WBC count and neutrophil count.

Discussion: smoking habit affects ciliar movement, inhibits alveolar macrophage function and produces hyperplasia on mucous glands within bronquial walls. These alterations result in entrapment of mucous secretions that will ultimately lead to bacterial colonization. The neutrophilia observed in smokers would be the result of a normal physiologic response to a potential infectious focus. In conclusion, is our understanding that the smoking habit should be considered as a common etiology for mild leucocytosis and neutrophilia.