Long term impact of sulfur mustard exposure on peripheral blood mononuclear subpopulations - Sardasht-Iran Cohort Study (SICS)

The most important long-term morbidity problem of sulfur mustard (SM) toxicity is pulmonary complications but the pathogenesis of these complications is not clearly understood. This study evaluates the peripheral blood mononuclear sub-sets and their correlation with pulmonary function in SM exposed civilian cases 20 years post-exposure as gathered in the context of the Sardasht-Iran Cohort Study (SICS). Samples were randomly selected from two groups, SM-exposed (n = 372) and control (n = 128), with the same ethnicity, culture, and demography. Three color flow cytometry was applied for peripheral blood mononuclear sub-population determination. Results indicated a significant decrease in CD45 +/CD3 +, CD45 +/CD3 +/CD4 +, and an increase in CD3 +/CD16+56 + percentages. It was also found that absolute count of NK cells was highly increased in peripheral blood of exposed cases. There was a significant increase in NK cell count of SM exposed group with pulmonary problems as compared to the same group without pulmonary problems (p-value < 0.04) based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD). The findings showed a significant negative correlation between absolute numbers of T lymphocyte and FVC % and positive correlation with FEV1/FVC%. The results also demonstrated that absolute numbers of monocytes had a negative correlation with FVC %. We propose that NK and T cells are probably involved in the pathogenesis or immune reactions to the delayed pulmonary complications induced by SM. This hypothesis should be tested in a more severe pulmonary complicated group.

► A significant decreased in CD45+/CD3+ and CD45+/CD3+/CD4+ percentages was found in peripheral blood of exposed cases. ► A significant increase in CD3+/CD16+56+ percentages and number was found in peripheral blood of exposed cases. ► An association was found between NK cell counts with pulmonary problems in SM exposed group. ► A negative correlation between absolute numbers of T lymphocyte and FVC % and positive correlation with FEV1/FVC was shown. ► NK and T cells are probably involved in the pathogenesis or control of the delayed SM induced pulmonary complications.