IL18 and bronchopulmonary dysplasia: These histological changes were accompanied by evidence of BPD-characteristic lung inflammation as increased counts for total leukocytes, lymphocytes, macrophages and neutrophils were found in BALF, and increased gene expression of the BPD-associated cytokines IL-18, TNF-α, CXCL1, CTGF and TGF-β1 was found in lung tissue samples.