The effect of dithiothreitol on chemotactic factors in induced sputum of chronic obstructive pulmonary disease patients.
BACKGROUND
Induced sputum analysis has been widely used to assay airway inflammation. However, the mucolytic agent dithiothreitol (DTT) may affect the detection of some soluble mediators.


OBJECTIVE
Our study was designed to investigate whether DTT affects the detection of monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1alpha and interleukin (IL)-10.


METHODS
Sputum samples were collected from 12 patients with chronic obstructive pulmonary disease (COPD) who were current or ex-smokers. The patients inhaled a 3% saline solution for 30 min from an ultrasonic nebulizer. Half of the sample collected was treated with 0.1% DTT and the other half was homogenized with phosphate-buffered saline (1x PBS) at room temperature. The total cell counts of the two portions were compared and the concentrations of MCP-1, MIP-1alpha and IL-10 in the supernatant were measured using immunoassays.


RESULTS
The median ratio of the forced expiratory volume in 1 s (FEV(1)) to the forced vital capacity was 46.0% (interquartile range 43.0-58.0%), and the median predicted FEV(1)% was 41% (interquartile range 36.0-44.0%). Sputum treated with DTT had higher total cell counts (p < 0.01) but lower levels of MCP-1 and MIP-1alpha (p < 0.02, p < 0.05) than that treated with PBS. The concentration of IL-10 was similar in DTT-treated and PBS-treated samples.


CONCLUSIONS
Sputum samples treated with DTT were homogenized more effectively and cell recovery was greater than in those treated with PBS. However, the detectable concentrations of MCP-1 and MIP-1alpha were significantly reduced in the sputum of DTT-treated samples.
Wang
Fei
F
Respiratory Department, Third Hospital, Peking University, Beijing 100083, China.
He
Bei
B
D000368:Aged; D018932:Chemokine CCL2 / Q000378:metabolism; D054405:Chemokine CCL3 / Q000378:metabolism; D002630:Chemotactic Factors / Q000378:metabolism*; D004229:Dithiothreitol; D005541:Forced Expiratory Volume; D006801:Humans; D016753:Interleukin-10 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000378:metabolism; D013183:Sputum / Q000378:metabolism*; D014797:Vital Capacity
C515429:CCL3 protein, human; D018932:Chemokine CCL2; D054405:Chemokine CCL3; D002630:Chemotactic Factors; D016753:Interleukin-10; D004229:Dithiothreitol