T lymphocytes compartmentalized on the epithelial surface of the lower respiratory tract express the very late activation antigen complex VLA-1.
T lymphocytes on the epithelial surface of the lower respiratory tract are thought to represent a relatively compartmentalized population of T cells that exchanges slowly with the blood. Since the lung is chronically burdened with antigens, "resident" T cells likely have a history of past activation. To evaluate this concept, we analyzed resident lung T cells for VLA-1 expression, which is indicative of a history of past stimulation. Lung lavage and blood T cells were evaluated in 13 normal nonsmokers using the monoclonal antibodies Leu4 (pan T cells), Leu3 (helper/inducer T cells), Leu2 (suppressor/cytotoxic T cells), TS2/7 (alpha 1 subunit of VLA-1), and A-1A5 (beta subunit of VLA-1) using immunofluorescence and immunoprecipitation. In contrast to normal blood T cells which did not express VLA-1, lung T cells expressed the 210-kDa alpha 1 and 130-kDa beta subunits of the VLA-1 complex, the same as blood T cells activated in culture for 3 weeks. Two-color immunofluorescence with Leu4 and TS2/7 showed that 19 +/- 6% of the lung T cells were VLA-1+, suggesting that a significant proportion of T lymphocytes on the alveolar epithelial surface are in a separate compartment from the VLA-1 blood cells. In sarcoidosis, a disease characterized by exaggerated numbers of active Leu3+ T cells in the lower respiratory tract, increased numbers of lung Leu3+ T cells expressing VLA-1 were present on the epithelial surface of the lung (P less than 0.05 compared to normals). These observations are consistent with compartmentalized, chronically stimulated T lymphocytes on the alveolar epithelial surface that exchange with the systemic immune system very slowly.
Saltini
C
C
Pulmonary Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892.
Hemler
M E
ME
Crystal
R G
RG
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation / Q000276:immunology*; D004848:Epithelium / Q000276:immunology; D005260:Female; D008168:Lung / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D011650:Pulmonary Alveoli / Q000276:immunology; D016029:Receptors, Very Late Antigen; D012507:Sarcoidosis / Q000276:immunology*; D012907:Smoking / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D016029:Receptors, Very Late Antigen