T regulatory cell phenotypes in peripheral blood and bronchoalveolar lavage from non-asthmatic and asthmatic subjects

• Published in: Clinical and experimental allergy Vol. 45; no. 11; pp. 1654 - 1662
• Main Authors: Baatjes, A. J., Smith, S. G., Watson, R., Howie, K., Murphy, D., Larché, M., Denburg, J. A., Inman, M. D., O'Byrne, P. M.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.11.2015; Wiley Subscription Services, Inc
• Subjects: Adult; Antigens, Surface - metabolism; asthma; Asthma - immunology; Asthma - metabolism; Asthma - physiopathology; BAL; Bronchoalveolar Lavage Fluid - cytology; Bronchoalveolar Lavage Fluid - immunology; Case-Control Studies; CD4 Lymphocyte Count; Female; flow cytometry; Forkhead Transcription Factors - metabolism; Foxp3; Humans; Immunophenotyping; Middle Aged; peripheral blood; Phenotype; suppression assay; T-Lymphocytes, Regulatory - immunology; T-Lymphocytes, Regulatory - metabolism; T regulatory cell; Young Adult; T regulatory cell; asthma; flow cytometry; peripheral blood; Foxp3; BAL; suppression assay
• ISSN: 0954-7894; 1365-2222; 1365-2222
• DOI: 10.1111/cea.12594

Summary Background An unresolved issue in T regulatory cells' cell biology is the lack of consensus on phenotypic markers that accurately define the natural Treg (nTreg) population. Objectives To examine nTreg frequency and functional capacity in healthy controls and their frequency in asthmatic subjects using three different phenotypic strategies. We hypothesized that phenotypically different nTreg are quantitatively and functionally different. Methods Thirty‐four healthy, non‐asthmatic and 17 asthmatic subjects were studied. Three nTreg phenotypes were defined as follows: nTreg1 (CD4+CD25+Foxp3+), nTreg2 (CD4+CD25+CD127lowFoxp3+), and nTreg3 (CD4+CD25highFoxp3+). The flow cytometric determination of nTreg frequency in peripheral blood (PB) and bronchoalveolar lavage (BAL) was performed using fluorescently labelled antibodies. Peripheral blood nTreg functional capacity was assessed using a CFSE‐based suppression assay. Results There was a significantly lower frequency of PB nTreg3 compared to nTreg2 and nTreg1 (P < 0.05). Both nTreg2 and nTreg3 had a significantly greater suppressive capacity than nTreg1 at T responder (Tresp) to nTreg ratios of 16 : 1 up to 1 : 1 (P < 0.01). Asthmatics exhibited a significantly lower PB nTreg3 and nTreg1 frequency than healthy controls (P < 0.05). There were no differences between healthy controls and asthmatic subjects when comparing BAL nTreg frequency. Conclusions and Clinical Relevance Phenotypically different nTreg subsets are quantitatively and functionally different and are variably observed in asthma. The CD4+CD25highFoxp3+ phenotype was the least frequent, but demonstrated the greatest suppression, and was significantly lower in PB of asthmatic subjects. Consequently, it is imperative that nTreg phenotypes be clearly defined and that the interpretation of their frequency and function be phenotype specific.