Background
Sulfur mustard is a chemical warfare agent that produces cellular damage via alkylation and protein cross-linking. Sulfur mustard affects the skin, lungs, and eyes, as well as the gastrointestinal, endocrinal, and hematologic systems. We studied the potential delayed toxic effects of sulfur mustard on white blood cells and some of its derivatives including polymorphonuclear lymphocytes and lymphocytes (CD4+ and CD8+) among Iranian veterans, approximately 25 years after exposure.
Material and Method
One hundred thirteen sulfur mustard-poisoned veterans registered for this prospective study. Hematologic, immunophenotyping, and flow cytometric evaluations were done to samples from patients as well as 20 healthy age- and sex-matched control volunteers. Hematologic and immunologic variables were compared between both groups of subjects. Values for P less than.05 were considered statistically significant.
Results
Total white blood cell count and percentage of polymorphonuclear lymphocytes were significantly higher in sulfur-mustard-exposed veterans than in control subjects (P=0.008 and <0.001). The percentages of total and CD4+ lymphocytes were significantly lower in sulfur-mustard-exposed veterans than they were in control subjects (P=0.008 and P<0.001). CD8+ lymphocyte percentage and CD4+/CD8+ ratio were not significantly different between the 2 groups.
Conclusions
Severe exposure to sulfur mustard may cause long-term damage to the immune system in humans. CD4+ T cells were significantly lower in persons exposed to sulfur mustard. However, there was no statistically significant between-group difference regarding CD8+ T cells. Impaired immunity may be responsible for the increased risk of infections in these patients.

Keywords: Time Factors, Occupational Exposure, Iran, Mustard Gas - poisoning, CD8-Positive T-Lymphocytes - drug effects, Veterans - statistics & numerical data, CD4-Positive T-Lymphocytes - drug effects