Sputum cytokines levels in patients undergoing hematopoietic SCT (HSCT) and comparison with healthy subjects and COPD: a pilot study

Patients undergoing hematopoietic stem cell transplantation (HSCT) display an airway neutrophilic inflammation before the transplantation that persists over the years. In this study, we have investigated the cytokine profile over a period of one year in sputum supernatant of patients who underwent HSCT. We have measured sputum supernatant levels of TNF-α, TGF-β1, IL-4, IL-5, IL-6, IL-8, IL-10, IL-13, IL-17, and IFN-γ in 49 HSCT patients and compared the results with those found in 40 COPD and 54 healthy subjects matched for age.
Compared to healthy subjects, before the transplantation, HSCT patients exhibited raised levels of IL-6 (p<0.001) and IL-8 (p<0.05) while the other cytokines were generally poorly detectable. This picture was rather similar to what is seen in COPD even if cytokine levels were much greater in the latter with IL-8 being significantly greater in COPD than in HSCT patients (p<0.0001). In the 1 year following the transplantation, sputum IL-6 and IL-8 did not differ any longer compared to healthy subjects. Overall in HSCT patients, sputum IL-8 and IL-6 correlated with sputum neutrophil counts (r=0.4, p<0.0001; r=0.42, p<0.0001, respectively).
In conclusion, sputum IL-6 and IL-8 may play a role in neutrophilic airway inflammation seen in patients undergoing HSCT.