Expression of IL-15 in inflammatory pulmonary diseases.
BACKGROUND
IL-15 is a T(H)1-related cytokine that shares many biologic activities with IL-2. Both cytokines bind a specific alpha subunit, and they share the same beta and gamma common receptor subunits for signal transduction. IL-15 has recently been shown to be upregulated in T cell-mediated inflammatory disorders, such as rheumatoid arthritis and inflammatory bowel diseases. However, the role and expression of IL-15 in inflammatory lung disease has not been investigated.


OBJECTIVE
In the present study we have evaluated the expression of IL-15 mRNA and protein in bronchial biopsy specimens obtained from patients with sarcoidosis (n = 8), tuberculosis (n = 7), chronic bronchitis (n = 10), and bronchial asthma (n = 8) and compared its expression with that seen in normal control subjects (n = 11).


METHODS
In situ hybridization and immunocytochemistry were used to detect the number of cells expressing IL-15 mRNA and protein, respectively, within sections of bronchial tissues from all subject groups. In addition, double immunocytochemistry was used to characterize the cellular source of IL-15.


RESULTS
The number of IL-15(+) cells was significantly higher within tissue from patients with sarcoidosis, tuberculosis, and chronic bronchitis compared with that in asthmatic patients and normal control subjects. Similar results were obtained for IL-15 immunoreactivity by using immunohistochemistry. Furthermore, double immunostaining revealed that neutrophils and macrophages are the major source of IL-15.


CONCLUSIONS
These results suggest that the expression of IL-15 may be associated with T(H)1-mediated chronic inflammatory diseases of the lung.
Muro
S
S
Meakins-Christie Laboratories and Montreal Chest Research Institute, McGill University, Montreal, Quebec, Canada.
Taha
R
R
Tsicopoulos
A
A
Olivenstein
R
R
Tonnel
A B
AB
Christodoulopoulos
P
P
Wallaert
B
B
Hamid
Q
Q
D001249:Asthma / Q000276:immunology*; D001991:Bronchitis / Q000276:immunology*; D006801:Humans; D007150:Immunohistochemistry; D019409:Interleukin-15 / Q000032:analysis* / Q000235:genetics / Q000502:physiology; D016209:Interleukin-8 / Q000502:physiology; D009504:Neutrophils / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D012507:Sarcoidosis / Q000276:immunology*; D018417:Th1 Cells / Q000502:physiology; D014397:Tuberculosis, Pulmonary / Q000276:immunology*
D019409:Interleukin-15; D016209:Interleukin-8; D012333:RNA, Messenger