Multicolor Flow Cytometric Analysis of Expression of T Cell Markers in Bronchoalveolar Lavage Fluid Cells and Peripheral Blood in Healthy Individuals.

Abstract

The aim of this study was to compare the expression of different surface markers on T lymphocytes in bronchoalveolar lavage (BAL) fluid and blood in healthy subjects. Twenty healthy non−smoking individuals (13 males), mean age 27 years (18−46), were included in the study. We analysed T cell markers CD3, CD4, and CD8, activation markers CD69, CD25 and HLA−DR, the T regulatory cell (Treg) marker FOXP3 and the costimulatory marker CD28, cytotoxic marker CD57 and intraepithelial marker CD103. Whole blood (after lysis of red blood cells) and paired BAL cells were analysed by flow cytometry using an 8 color FACSCanto II (BD Biosciences, USA). Approximately 2.5x10 5 cells were analysed in each sample.Results: The CD4/CD8 ratio was similar in both compartments (median 2.2 vs 2.0, n.s.). The percentage of CD4 + cells expressing FOXP3 was significantly higher in BAL compared to blood (median 8.0 % vs 2.4 %, p< 0.0001). The frequencies of CD4 + cells expressing the activation markers CD69 and HLA−DR, as well as CD57 and CD103 were also significantly higher in BAL fluid compared to blood, and similar results applied to CD8 + cells. In contrast, the expression of the costimulatory molecule CD28 was significantly reduced in BAL cells.