Lymphocytic Subpopulation Profiles in Bronchoalveolar Lavage Fluid and Peripheral Blood From Tobacco and Marijuana Smokers: Data Analysis

Because most of the outcome variables were not normally distributed, the data were log transformed before analysis. Analysis of covariance (ANCOVA) was used to investigate the differences in cell percentages and concentrations among the subject groups, with sex and age as covariates. One-way ANCOVA was used to compare all smoking categories (NS, TS, MS, and MTS). Multiple comparisons were performed by the Tukey-Kramer method. Two-way ANCOVA was used to determine the effects of tobacco and marijuana independently and the interaction between them. Correlation analysis was used to determine the presence of any cell percentage or concentration dose-response relationships with lifetime tobacco and marijuana smoking amounts, using pure tobacco and marijuana smokers, respectively. Correlations were also performed between FEV,/ FVC and percent of predicted Deo, and each of the log percentages and concentrations of bronchoalveolar cells. Student’s t test was used to compare smoking amounts between marijuana and tobacco smoking groups and the volume of BAL fluid recovered among the four groups. A p value of less than 0.05 was considered significant for all statistical tests. Analyses were performed using SAS statistical software programs.
The age and gender distribution and mean lifetime cigarette and marijuana consumption among the four subject groups are shown in Table 1. The mean ages and male-female ratios were similar among the four groups. The lifetime tobacco consumption was similar between TS and MTS, and both MS and MTS had heavy lifetime marijuana consumption. Although the number of “joint-years” was greater in MS, the amount consumed among individuals varied widely, and there was no statistically significant difference between the MS and MTS groups. Table 2 shows the bronchoalveolar cellular composition in the four study groups. The percentages of alveolar macrophages (AM), lymphocytes, or neutrophils did not differ significantly among the four groups.
The highest mean cell concentrations were observed in the MTS group. Total cell and AM concentrations were significantly higher in TS, MS, and MTS compared with NS, and in TS and MTS compared with MS. Both TS and MTS had significantly higher concentrations of lymphocytes compared with NS.

Table 1—Age у Gender, Marijuana Use, and Cigarette Use Among the Four Subject Groups

Nonsmokers TobaccoSmokers MarijuanaSmokers Marijuana and Tobacco Smokers
No. of subjects 14 14 19 9
Mean age,e vr 35.5 ± 1.9 37.5 ±2.0 35.4 ± 1.6 34.1 ±2.3
Male:female ratio 10:4 11:3 13:6 8:1
Cigarette use, (pack-vears)*f 22.7 ±4.2 19.8 ±5.7
Marijuana use, (joint-vears)*f 85.3 ±21.1 45.4 ±9.7

Table 2—Bronchoalveolar Cellular Composition in the Four Subject Groups (Data Expressed as Mean ± SEM)

Nonsmokers TobaccoSmokers MarijuanaSmokers Marijuana and Tobacco Smokers
Volume recovered, ml 241.3 ± 2.6* 191.5 ± 12.2t 217.7 ±7.2 212.8 ± 13.9
Alveolar macrophages, % 89.2 ± 1.5 93.2 ±0.5 92.6 ± 1.1 93.0 ± 1.4
Lymphocytes, % 10.0 ± 1.5 5.9 ±0.5 7.0 ± 1.0 5.9 ± 1.3
Neutrophils, % 0.5 ±0.1 0.9 ±0.2 0.3 ±0.1 0.8 ±0.3
Total cells, x l()/ml из± io*|§ 601± 106t| 336 ± 54.0*f § 807 ± 1741\
Alveolar macrophages, x lOVml 99.7 ± 8.2*t§ 561 ± 99.7ft 312 ± 50.9*f § 745± 156ft
Lymphocytes, x 103/ml 12.1±2.4*§ 31.9 ± 5.Of 22.8 ±4.2 51.3 ± 18.4f
Neutrophils, x 103/ml 0.6 ±0.1 7.4 ± 2.7$ 0.9 ±0.3* 6.7 ±3.4

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