Table 1 Baseline characteristics of the patients

Number

29

59

76

–

Age (years)

68 (66–75)

71 (66–78)

71 (61–78)

0.497

Male, n (%)

18 (62.1 %)

32 (54.2 %)

37 (48.7 %)

0.458

WBC (×10⁹/L)

6.9 (5.6–7.9)

13.3 (10.9–17.8)

14.9 (11.8–17.2)

<0.001

Lymphocyte (×10⁹/L)

2.8 (2.4–3.1)

1.06 (0.73–1.63)

0.76 (0.54–1.07)

<0.001

SOFA score

0

5 (3–7)

11 (9–14)

<0.001

SAPS II

12 (12–15)

26 (24–32)

53 (46–60)

<0.001

Percentage of PD-1⁺/CD4⁺ T cells (%)

26.2 (23.2–29.9)

34.1 (28.4–44.4)

38.2 (29.2–47.7)

<0.001

MFI of PD-1 on CD4⁺ T cells

6.3 (5.8–6.8)

7.1 (5.2–9.2)

7.5 (6.0–9.4)

0.008

Percentage of PD-1⁺/CD8⁺ T cells (%)

22.6 (18.7–28.2)

31.6 (23.9–46.6)

36.5 (27.3–51.3)

<0.001

MFI of PD-1 on CD8⁺ T cells

5.9 (4.8–6.6)

6.4 (4.2–7.5)

6.6 (4.9–8.4)

0.181

Percentage of PD-L1⁺/CD4⁺ T cells (%)

18.2 (12.3–22.6)

21.5 (16.5–30.5)

21.0 (9.3–30.6)

0.021

MFI of PD-L1 on CD4⁺ T cells

1.8 (1.6–2.2)

1.8 (1.6–2.6)

1.8 (1.5–2.0)

0.230

Percentage of PD-L1⁺/CD8⁺ T cells (%)

22.6 (17.1–26.2)

18.8 (14.9–37.6)

19.5 (10.3–37.4)

0.645

MFI of PD-L1 on CD8⁺ T cells

1.5 (1.4–1.7)

1.6 (1.2–2.1)

1.5 (1.4–1.8)

0.596

Percentage of monocytes expressing PD-L1 (%)

12.9 (10.4–15.3)

29.2 (12.1–43.9)

35.9 (20.4–54.7)

<0.001

MFI of PD-L1 on monocytes

3.4 (3.0–3.9)

4.5 (2.2–7.5)

8.3 (7.7–9.7)

<0.001

Pneumonia

0

30 (50.8 %)

41 (53.9 %)

0.731

IAI

0

7 (11.8 %)

11 (14.5 %)

0.658

CNSI

0

5 (8.5 %)

6 (7.9 %)

0.903

USI

0

17 (28.8 %)

18 (23.7 %)

0.500

≥1, n (%)

0

11 (18.6 %)

39 (51.3 %)

<0.001

28-day mortality, n (%)

0

10 (16.9 %)

27 (35.5 %)

0.016