Soluble human leucocyte antigen-G and interleukin-10 levels in isocyanate-induced asthma

Background: We previously reported that in moderate to severe asthma there is a deficit of interleukin-10 secretion that could prevent the production of soluble HLA-G (sHLA-G), a nonclassical human leukocyte antigen class I molecule with tissue-protective properties in inflammatory responses. Objective: Our objective was to investigate the production of sHLA-G and the secretion of interleukin-10 by peripheral blood mononuclear cells (PBMCs) in asthma induced by isocyanates and to compare the results with those obtained in nonoccupational allergic asthma. Method: sHLA-G and interleukin-10 were measured by enzyme-linked immunosorbent assay in culture supernatants of unstimulated or lipopolysaccharide-stimulated PBMCs obtained from 20 subjects with isocyanate asthma, 16 asymptomatic subjects exposed to isocyanates, 18 subjects with nonoccupational allergic asthma, and 26 healthy control subjects. Results: Occupational exposure to isocyanates was associated with high baseline levels of secretion of interleukin-10 by PBMCs, whether or not the exposed subjects had asthmatic symptoms. However, spontaneous production of sHLA-G by PBMC was significantly higher in subjects with isocyanate asthma compared with asymptomatic exposed controls. In contrast, PBMCs from subjects with nonoccupational allergic asthma produced sHLA-G only after lipopolysaccharide stimulation. Conclusions: sHLA-G production and interleukin-10 secretion are influenced by workplace exposure to isocyanates and by development of asthma. The different behaviour of both sHLA-G and IL-10 in asthma induced by isocyanates compared to nonoccupational allergic asthma suggests an heterogeneous biological role for HLA-G molecules and for IL-10, a key cytokine of immune and inflammatory responses