Increased levels of interleukin-18 in bronchoalveolar lavage fluid of patients with idiopathic nonspecific interstitial pneumonia.
BACKGROUND
Interleukin-18 (IL-18) is a proinflammatory cytokine that can induce interferon-gamma (IFN-gamma), and it plays an important role in T-helper 1 responses. Among idiopathic interstitial pneumonia (IIP), nonspecific interstitial pneumonia (NSIP) has an increased number of lymphocytes in bronchoalveolar lavage (BAL) fluid compared with usual interstitial pneumonia (UIP). However, the difference in their pathogenesis is unclear.


OBJECTIVE
The present study aims to investigate the roles of IL-18 in patients with idiopathic UIP and idiopathic NSIP.


METHODS
We measured the serum and BAL fluid (BALF) levels of IL-18 and IFN-gamma in 22 patients with IIP (12 with UIP, 10 with NSIP) and 9 healthy volunteers.


RESULTS
Lymphocyte proportions in BALF were significantly higher in NSIP than in UIP and healthy subjects. No significant differences were observed in the serum IL-18 levels of all subjects, while the BALF levels of IL-18 in patients with NSIP were significantly higher than in patients with UIP (p < 0.005) and in healthy subjects (p < 0.005). Among all subjects, the levels of IL-18 in BALF correlated significantly with those in serum and the lymphocyte proportions in BALF. The serum IFN-gamma levels of all subjects were below sensitivity, but there was significant reverse correlation between the levels of IFN-gamma and the lymphocyte proportions in BALF.


CONCLUSIONS
The lymphocytosis in BALF of patients with idiopathic NSIP and a part of idiopathic UIP might be associated with the high levels of IL-18.
Ishii
Hiroshi
H
Second Department of Internal Medicine, Nagasaki University School of Medicine, Nagasaki, Japan.
Mukae
Hiroshi
H
Kadota
Jun-ichi
J
Fujii
Takeshi
T
Abe
Koh
K
Ashitani
Jun-ichi
J
Kohno
Shigeru
S
D000328:Adult; D000368:Aged; D000941:Antigens / Q000097:blood; D000951:Antigens, Neoplasm; D015415:Biomarkers / Q000378:metabolism; D001706:Biopsy; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology* / Q000276:immunology; D016516:CD4-CD8 Ratio; D004797:Enzyme-Linked Immunosorbent Assay; D004804:Eosinophils / Q000166:cytology; D005260:Female; D005434:Flow Cytometry; D019085:Fluorescent Antibody Technique, Direct; D006023:Glycoproteins / Q000097:blood; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D020382:Interleukin-18 / Q000276:immunology / Q000378:metabolism*; D017563:Lung Diseases, Interstitial / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008218:Lymphocytosis / Q000276:immunology* / Q000473:pathology; D016676:Macrophages, Alveolar / Q000166:cytology / Q000276:immunology; D008297:Male; D008875:Middle Aged; D018396:Mucin-1; D009077:Mucins; D009504:Neutrophils / Q000166:cytology; D037662:Pulmonary Surfactant-Associated Protein A / Q000097:blood
D000941:Antigens; D000951:Antigens, Neoplasm; D015415:Biomarkers; D006023:Glycoproteins; D020382:Interleukin-18; C060192:MUC1 protein, human; D018396:Mucin-1; D009077:Mucins; D037662:Pulmonary Surfactant-Associated Protein A; D007371:Interferon-gamma