Table III.
Serum levels of cytokines stratified by smoking status in the control and diesel engine exhaust exposure groups (Median, 10%−90%)
| Control group | Diesel engine exhaust exposure group | Difference in median levels (%) | Pcrudeb | Padjustc | FDRd | Pint.e | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Cytokines | n | Median (10%−90%) | Pa | n | Median (10%−90%) | Pa | |||||
| IL-1β (pg/ml) | |||||||||||
| Non-smokers | 16 | 1.2 (1.2–16.0) | 14 | 1.2(1.2–5.9) | 0.0 | 0.45 | - | - | |||
| Current smokers | 30 | 1.2(1.2–7.6) | 0.92 | 27 | 1.2(1.2–25.4) | 0.61 | 0.0 | 0.71 | - | - | |
| Total | 46 | 1.2(1.2–7.5) | 41 | 1.2(1.2–6.7) | 0.0 | 0.47 | - | - | - | ||
| IL-6 (pg/ml) | |||||||||||
| Non-smokers | 16 | 7.4(5.2–15.2) | 14 | 7.2(3.5–22.9) | −2.7 | 0.67 | 0.56 | 0.90 | |||
| Current smokers | 30 | 7.0 (5.2–12.7) | 0.38 | 27 | 7.4(5.6–19.7) | 0.94 | 5.7 | 0.81 | 0.81 | 0.96 | |
| Total | 46 | 7.2(5.2–12.8) | 41 | 7.4(5.8–21.3) | 2.8 | 0.96 | 0.86 | 0.96 | 0.51 | ||
| IL-8 (pg/ml) | |||||||||||
| Non-smokers | 16 | 10.1(8.0–15.8) | 14 | 9.9(8.8–16.5) | −2.0 | 0.84 | 0.84 | 0.96 | |||
| Current smokers | 30 | 12.2 (9.3–18.5) | 0.031 | 27 | 11.6(9.0–17.5) | 0.16 | −4.9 | 0.72 | 0.81 | 0.96 | |
| Total | 46 | 11.9(8.5–18.0) | 41 | 10.9(9.0–16.9) | −8.4 | 0.86 | 0.63 | 0.90 | 0.89 | ||
| MIP-1β (pg/ml) | |||||||||||
| Non-smokers | 16 | 64.0(26.2–135.9) | 14 | 53.4(28.6–239.2) | −16.6 | 0.98 | 0.97 | 0.98 | |||
| Current smokers | 30 | 75.7(38.7–131.2) | 0.22 | 27 | 36.3(10.7–110.8) | 0.048 | −52.0 | <0.001 | <0.001 | 0.001 | |
| Total | 46 | 71.1(31.4–130.8) | 41 | 44.7(15.6–186.6) | −37.1 | 0.002 | <0.001 | 0.003 | 0.06 | ||
| MCP-1 (pg/ml) | |||||||||||
| Non-smokers | 16 | 95.6(39.4–254.8) | 14 | 101.9(26.8–167.0) | 6.6 | 0.93 | 0.98 | 0.98 | |||
| Current smokers | 30 | 126.8(65.9–200.3) | 0.53 | 27 | 97.2(55.4–236.2) | 0.25 | −23.3 | 0.33 | 0.43 | 0.78 | |
| Total | 46 | 106.7(59.3–203.9) | 41 | 99.9(54.6–187.6) | −6.4 | 0.64 | 0.63 | 0.90 | 0.82 | ||
| TNF-α (pg/ml) | |||||||||||
| Non-smokers | 16 | 0.6(0.6–12.7) | 14 | 0.6(0.6–4.3) | 0 | 0.45 | - | - | |||
| Current smokers | 30 | 0.6(0.6–5.9) | 0.56 | 27 | 0.6(0.6–20.3) | 0.29 | 0 | 0.88 | - | - | |
| Total | 46 | 0.6(0.6–5.1) | 41 | 0.6(0.6–5.0) | 0 | 0.59 | - | - | - | ||
a,
t-test for difference between non-smokers and current smokers
b,
t-test for difference between control and diesel engine exhaust exposure groups for IL-6, IL-8, MIP-1β, and MCP-1. For IL-1β and TNF-α, the Mann-Whitney U test was used to compare exposure groups given the large percentage of samples below detection (58% and 67%, respectively)
c,
Adjusted for age, alcohol status, infection status, body mass index, and smoking status.
d,
Multiple comparisons were adjusted for by applying the false discovery rate (FDR) using the Benjamini-Hochberg method
e,
P value for interaction between DEE exposure and smoking.