Are serum levels of immunoglobulin classes and IgG subclasses involved in delayed pulmonary complications induced by sulfur mustard? Sardasht-Iran Cohort Study.

Respiratory complications are the foremost long term debilitating effects after sulfur mustard toxicity. The underlying immunological mechanisms of sulfur mustard induced lung damage are still poorly understood. The question of the involvement of immunoglobulin classes and subclasses in delayed pulmonary complications induced by SM was addressed in this study as a part of Sardasht-Iran Cohort Study (SICS).In SICS, 372 male participants who were exposed to SM 20 years earlier were compared with 128 unexposed age-matched controls. At the time of study (2007), the clinical evaluations and spirometry was performed for all subjects according to the American Thoracic Society Criteria, and at the same time, the sera were isolated, labeled and aliquots were kept frozen in -80°C. Serum immunoglobulin (Ig) levels including IgM, IgA, IgE, IgG, and IgG subclasses (IgG1, IgG2, IgG3 and IgG4) were measured using quantitative Elisa method. It was found that among immunoglobulin classes and IgG subclasses only IgM and IgG4 were significantly decreased in the peripheral blood of exposed cases. IgM level also positively correlated with FEV1 only in the SM exposed group. These results indicated a weak but significant role for IgA in control of the delayed pulmonary complications. There were no strong correlations between other immunoglobulin classes or IgG subclasses with pulmonary disease severity in sulfur mustard intoxicated subjects. The authors proposed that systemic levels of immunoglobulins do not exert essential roles in severity of delayed pulmonary complications following SM toxicity. However, more studies on local and systemic levels of immunoglobulins in more severe groups are suggested.