Dithiothreitol has a dose-response effect on cell surface antigen expression

The use of Dithiothreitol (DTT) to improve cell dispersion is an integral step in induced sputum examination, which has become an important noninvasive method of assessing airway inflammation. Several studies have shown that sputum treatment with DTT does not affect cell morphology, differential cell counts, and cytokine levels in the supernatant. However, the effect of DTT on cell surface marker expression has not been systematically studied.

We have investigated the effect of different DTT concentrations on antigen expression on peripheral blood cells compared with antigen expression on PBS-treated cells.

Peripheral blood from different healthy donors was incubated with either DTT or PBS, washed, and then incubated with different fluorescence-labeled antibodies. Analysis was performed after lysis of erythrocytes on a calibrated flow cytometer. Respective cell populations were identified, and the mean fluorescence intensity of surface-marker expression for each cell population was compared between DTT- and PBS-treated cells.

We found that DTT decreased the expression of CD11a and CD49d on lymphocytes and eosinophils. The expression of CD11a on neutrophils was also decreased after DTT treatment. DTT increased CD11b expression on lymphocytes, neutrophils, and eosinophils. DTT might also have a mild effect on cell activation. It decreased the expression of CD2 on lymphocytes and variably affected the expression of EG2 in eosinophils, although it had no significant effect on HLA-DR expression on lymphocytes.

Our findings show that DTT can affect antigen expression on lymphocytes, neutrophils, and eosinophils and suggest the need for further investigation of similar consequences on induced sputum analysis.