Indication for a role of regulatory T cells for the advent of influenza A (H1N1)-related pneumonia

• Published in: Clinical and experimental immunology Vol. 161; no. 3; pp. 576 - 583
• Main Authors: Raftogiannis, M, Antonopoulou, A, Baziaka, F, Spyridaki, A, Koutoukas, P, Tsaganos, T, Savva, A, Pistiki, A, Georgitsi, M, Giamarellos-Bourboulis, E.J
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01-09-2010; Blackwell Publishing Ltd; Oxford University Press; Blackwell Science Inc
• Subjects: Adult; Aged; Blood; CD14 antigen; cytokines; Enzyme immunoassay; Female; Flow Cytometry; H1N1 influenza; Histocompatibility antigen HLA; HLA-DR Antigens - metabolism; Humans; Immunophenotyping; Immunoregulation; Infection; Inflammation; Influenza A; Influenza A Virus, H1N1 Subtype - immunology; Influenza, Human - blood; Influenza, Human - complications; Influenza, Human - immunology; Interleukin 10; Interleukin-6 - blood; Leukocytes; Lipopolysaccharide Receptors - metabolism; Lymphocytes T; Male; Membrane Glycoproteins - blood; Middle Aged; Monocytes; Pneumonia; Pneumonia, Bacterial - blood; Pneumonia, Bacterial - complications; Pneumonia, Bacterial - immunology; procalcitonin; Receptors, Immunologic - blood; Regression analysis; regulatory T cells; Sampling; T-Lymphocytes, Regulatory - immunology; T-Lymphocytes, Regulatory - metabolism; Translational Studies; Triggering Receptor Expressed on Myeloid Cells-1; Tumor necrosis factor-a; Tumor Necrosis Factor-alpha - blood; Young Adult
• ISSN: 0009-9104; 1365-2249
• DOI: 10.1111/j.1365-2249.2010.04208.x

Regulatory T cells (Tregs) have an anti-inflammatory role. A former study in a limited number of patients found that absolute counts of Tregs increase when infection by the new influenza H1N1 virus is complicated with pneumonia. These results generate the question if H1N1-related pneumonia is associated with a state of hypo-inflammation. A total of 135 patients were enrolled with blood sampling within less than 24 h from diagnosis; 23 with flu-like syndrome; 69 with uncomplicated H1N1-infection; seven with bacterial pneumonia; and 36 with H1N1-related pneumonia. Tregs and CD14/HLA-DR co-expression were estimated by flow cytometry; concentrations of tumour necrosis factor-alpha (TNF-α), of interleukin (IL)-6 and of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) by an enzyme immunoassay; those of procalcitonin (PCT) by immuno-time-resolved amplified cryptate technology assay. Expression of human leucocyte antigen D-related (HLA-DR) on monocytes was similar between groups; absolute Treg counts were greater among patients with H1N1-related pneumonia than flu-like syndrome or H1N1-uncomplicated infection. Serum TNF-α of patients with bacterial pneumonia was greater than those of other groups, but IL-10 was similar between groups. Serum PCT was greater among patients with H1N1-related pneumonia and sTREM-1 among those with H1N1-related pneumonia. Regression analysis revealed that the most important factors related with the advent of pneumonia were the existence of underlying illnesses (P = 0·006) and of Tregs equal to or above 16 mm³ (P = 0·013). It is concluded that the advent of H1N1-related pneumonia is related to an early increase of the absolute Treg counts. This increase is probably not part of a hypo-inflammatory state of the host.