Fig. 1: Changes in immune cells in tracheal aspirations (TA) obtained from preterm infants.

a, b Comparisons of the frequencies and counts of CD14⁺CD16⁺ inflammatory monocytes and CD14⁺CD163⁺ macrophages in TA between the BPD group (n = 40) and non-BPD group (n = 22) in the first week of life using 2001NICHD criteria and 2019 Jensen criteria. c, d Comparisons of frequencies and counts of CD14⁺CD16⁺ inflammatory monocytes and CD14⁺CD163⁺ macrophages in TA between patients who were eventually diagnosed with moderate-severe BPD (n = 21) and mild BPD (n = 19) or grade 1, 2, 3 using 2001 NICHD criteria and 2019 Jensen criteria separately. e The dynamic changes of frequencies of CD14⁺CD16⁺ inflammatory monocytes, CD14^-CD16⁺ neutrophils, CD14⁺CD163⁺ macrophages and CD14⁺CD68⁺ macrophages in TA during the first month of life. Student’s t test or Mann–Whitney test was used for comparison between two groups. P < 0.05 indicates statistical significance.