Immune-modulatory Effect of Ionizing Radiation on Type 1 and Type 2 Immune Responses among Workers in Cardiac Catheterization Units

Abstract

Introduction: It has long been known that ionizing radiation induced damage of the immune system. However, substantial evidence suggests more varied effects of radiation on the immune system, prompting the re-characterization of radiation as ‘immune-modulatory’ rather than immune-suppressive. Objective: This study aimed at investigating the effect of occupational exposure to ionizing radiation on the immune system, particularly the effect on the balance between type 1(Th1) and type 2(Th2) immune response. Methods: A group of 47 cardiac catheterization workers (19 physicians,15 nurses and 13 technicians) and another 47 job, age, and sex  matched controls were subjected to investigating the level of Th1 cytokines (IL2, INFγ), Th2 cytokines (IL10) and CD4%. Annual personal exposure was monitored by TLD (thermoluminescent dosimeter) readings over the last 3 years Results: Dosimeter readings were within the acceptable level over the last three years preceding to the study. There is statistically significantly higher level of Th1 cytokines (IL2, IFNγ) along with statistically significant lower levels of Th2 cytokines ( IL10) associated with lower CD4% among the exposed compared to control groups (P<0.05). Significant positive correlation was detected between the mean TLDs readings and each of IL2 (r=0.617 P<0.001) and IFN γ (r= 0.560 P<0.001). On the other hand, significant negative correlation was detected between mean TLDs readings and CD4% (r= -0.312 p<0.05). ANOVA and Post Hoc tests showed significantly higher level of Th1 cytokines with significantly lower levels of Th2 cytokines and CD4% among the physicians compared to control group Conclusion: Occupational exposure to low dose ionizing radiation induce switch of the immune system to Th1 immune response.