Table 2 Differences in immune cell counts in blood between night-shift workers and non-shift workers.

From: Immunological effects of shift work in healthcare workers

Cells/μl blood

Night-shift workers (n = 254)

Non-shift workers (n = 57)

Night-shift workers vs. non-shift workers

mean (SD)

median (IQR)

mean (SD)

median (IQR)

B (95%-CI)a,b

Monocytes

423.9* (133.7)

403.1* (171.3)

378.1* (135.5)

362.5* (184.0)

1.15* (1.05–1.26)

Granulocytes

3958.5 (1515.0)

3723.0 (1603.3)

3751.3 (1329.0)

3570.5 (1493.4)

1.04 (0.93–1.16)

Lymphocytes

2109.3 (660.2)

2019.4 (775.0)

1953.3 (557.3)

1925.4 (734.9)

1.04 (0.95–1.14)

NK cells

236.1 (124.7)

212.7 (156.6)

263.2 (117.1)

238.2 (137.2)

0.89 (0.76–1.05)

NKT cells

83.0 (83.6)

57.1 (72.4)

76.1 (66.4)

52.9 (81.6)

1.03 (0.81–1.31)

B cells

243.6 (126.2)

219.1 (137.8)

217.4 (99.5)

210.2 (131.3)

1.05 (0.91–1.22)

T cells

1545.8* (523.8)

1479.7* (628.4)

1397.3* (462.0)

1328.9* (675.1)

1.05 (0.96–1.16)

CD4 T cells

976.1 (348.4)

936.0 (433.6)

927.6 (333.6)

871.2 (361.3)

1.02 (0.92–1.13)

   CD4 effector memory T cells

105.8 (63.5)

90.7 (64.4)

103.2 (62.2)

85.3 (60.9)

1.08 (0.94–1.24)

   CD4 central memory T cells

359.7 (142.8)

334.4 (163.7)

339.4 (130.4)

318.4 (179.4)

1.03 (0.93–1.15)

   CD4 naive T cells

489.5 (243.9)

457.5 (305.2)

461.8 (242.0)

397.0 (227.1)

0.97 (0.83–1.14)

   CD4 effector T cells

21.1 (29.9)

9.6 (18.2)

23.2 (35.5)

11.1 (19.5)

0.84 (0.63–1.13)

CD8 T cells

443.8* (213.9)

417.7* (249.4)

360.3* (193.0)

317.6* (229.0)

1.14 (1.00–1.29)

   CD8 effector memory T cells

32.8 (30.2)

25.8 (25.7)

31.7 (35.4)

19.1 (18.7)

1.20 (0.96–1.50)

   CD8 central memory T cells

77.7* (43.2)

65.9* (52.9)

64.8* (35.8)

54.6* (53.5)

1.17 (0.99–1.38)

   CD8 naive T cells

225.6* (129.8)

194.9* (159.0)

168.6* (84.3)

149.2* (133.5)

1.08 (0.92–1.26)

   CD8 effector T cells

107.7 (119.9)

68.0 (98.9)

95.3 (98.2)

53.2 (102.5)

1.01 (0.81–1.27)

CD4/CD8 T cell ratio

2.6* (1.6)

2.2* (1.4)

3.1* (1.6)

2.9* (1.7)

0.90 (0.80–1.02)

  1. B, regression coefficient; CI, confidence interval; IQR, interquartile range; SD, standard deviation.
  2. T cell subsets: Effector memory T cells: CD27−/CD45RO+, Central memory T cells: CD27+/CD45RO+, Naive T cells: CD27+/CD45RO−, Effector T cells: CD27−/CD45RO−.
  3. *Statistically significant difference (p < 0.05) between night-shift workers and non-shift workers tested using the independent-samples t-test for normally distributed outcomes (column 1 and 2), the Mann-Whitney U test for non-normally distributed outcomes (column 1 and 2), and adjusted mixed model regression analysis for the log-transformed outcomes (column 3).
  4. aThe regression coefficients are ratios between geometric means of night-shift workers and non-shift workers.
  5. bAdjusted for age, gender, CMV status, occupation, educational level, general perceived health, smoking status, influenza vaccination status, and recent infection.
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