Role of antibodies and T cells in pigeon fanciers' lung

Nademi, Zohreh (2009) Role of antibodies and T cells in pigeon fanciers' lung. Doctoral thesis, Northumbria University.

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Abstract

Abstract: Introduction: Pigeon fanciers’ lung (PFL) is one of the most common forms of hypersensitivity pneumonitis (HP) in the UK. Generally it is considered that PFL is caused by immune complexes, however, this does not explain why some fanciers are asymptomatic despite the presence of high levels of anti-avian antigen antibodies in their serum. Pigeon intestinal mucin (PIM) is considered to be an important antigen in PFL. Thus this study was designed in order to understand the role of specific antibodies and T cells in the pathogenesis of PFL. Methods: Anti-avian IgG and IgG subclass responses among 50 symptomatic and 50 asymptomatic pigeon fanciers were determined by ELISA and the functional affinity of IgG1 and IgG2 against a range of pigeon antigens was determined by inhibition ELISA and microcalimetry. Mucin-specific T cell clones were also generated from pigeon fanciers and T cell phenotypes and cytokine profile of these cells were identified. Results: The median titres of IgG1 and IgG2 against all the pigeon antigens tested was always higher in asymptomatic than symptomatic fanciers and these differences were significant for anti-PS IgG1 (P=0.04), anti-PDF IgG2 (P=0.028), anti-PDO IgG2 (P=0.04) and anti-PIS IgG2 (P=0.03). The functional affinity of IgG1 and IgG2 against PDO was higher in symptomatic individuals as compared to asymptomatic fanciers (P=0.006 and P=0.002, respectively) whilst the functional affinity of anti-PDF IgG2 was also significantly higher in these patients (P?0.001). Symptomatic fanciers were also significantly more likely to have high ?H and thus had higher avidity antibodies against PDO (P=0.044). 12 T cell clones specific for t mucin also were generated from an asymptomatic fancier and 90-96% of clone 04, 22, 23 were CD4-CD8- double negative (DN). Conclusion: The data suggests that the magnitude of the serum antibody response cannot determine the development of the disease and as symptomatic fanciers had higher IgG antibody avidities and therefore immune complexes in individuals with PFL may have a stronger composition and bonds. In addition, this is the first demonstration of the use of ITC to measure antibody avidity in a clinical situation. This is a rapid and simple method of measuring antibody avidity and has a diagnostic potential in PFL. Finally t mucin-specific T cell clones with double negative phenotype may have a crucial role in immune regulation in asymptomatic fanciers and can be one of the reasons why these individuals do not have any symptoms in spite of having high antibody responses.

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