Cigarette smoking depletes cells spontaneously secreting Th-1 cytokines inthe human airway

Cigarette smoking may modify the immune balance in the airway since it alte rs the course of diseases in which immune system has an important role, Thi s study examined whether cigarette smoking could affect the distribution of cells secreting Th, or Th, cytokines in the human airway. We utilized cyto kine ELISPOT assay to detect and quantitate the frequencies of cells sponta neously secreting cytokines in bronchoalveolar lavage fluid (BALF), BALF wa s collected from six non-smokers and four heavy cigarette smokers without c linical airway symptoms. Cytokine ELISPOT assay was performed to quantitate cells secreting interleukin (IL-)2, IL-4 and interferon (IFN-)gamma with o r without phorbor 12-myristate 13-acetate (PMA) stimulation. There were no cells spontaneously secreting IL-2 detected in all samples from smokers whe reas most of non-smokers had detectable IL-2-secreting cells. The number of IFN-gamma -secreting cells was also extremely decreased in smokers. Mitoge n-stimulated Th, cytokine-secreting cells were again significantly decrease d in smokers' airways, The frequency of IL-2-secreting cells and CD4/CD8 ra tio in BALF had a weak positive correlation. IL-Lt-secreting cells were not detected in any samples from both groups. These results show that cigarett e smoking depletes Th, cytokine-secreting cells in the human airway. It may explain the susceptibility of smokers to certain airway disease conditions such as viral or mycobacterial infections and allergic diseases. (C) 2001 Academic Press.