Phenotypic and molecular characterization of CD103+ CD4+ T cells in bronchoalveolar lavage from patients with interstitial lung diseases

Background: The integrin CD103 is preferentially expressed on intraepithelial T lymphocytes, and cells expressing this integrin may play a regulatory role in the microenvironment of the epithelial cell layer. Methods: The relative number of CD103(+)/CD4(+) T cells in the bronchoalveolar lavage was significantly elevated in all patients diagnosed with interstitial lung diseases compared with patients with other non-fibrotic disorders of the lung. Results: Analysis by flow cytometry showed that the CD103(+) and the CD103(-) subpopulations were memory T cells based on the high expression of CD45R0(+). However, the CD103(+)/CD4(+) T cells were CD25(low), CD27(-), CD28(low), and CD62L(-), whereas the CD103(-)/CD4(+) T cells expressed CD25 and CD62L and were CD27(high) and CD28(high). In addition, the CD103(+)/CD4(+) T cells expressed significantly higher quantities of VLA-1 and CD101 than did CD103(-)/CD4(+) T cells. Reverse transcriptase polymerase chain reaction analysis of purified CD103(+) and CD103(-) CD4(+) T cells showed production of tumor necrosis factor (TNF) alpha-R-1 (p55), TNF-alpha-R-2 (p75), interferon gamma, interleukin-10 and TNF-alpha mRNA in both subpopulations. No interleukin-4 mRNA was detected in either subpopulation. Conclusions: CD103(+)/CD4(+) T cells represent a T-helper 1-like subpopulation in human lungs with a distinct effector phenotype. Despite the lack of CD27 and the low CD25 and CD28 expression, these cells show a high degree of activation. These results suggest that CD103 expressing CD4 T cells in the lung are continuously activated, long-living cells. (C) 2003 Wiley-Liss, Inc.