Polycyclic aromatic hydrocarbons (PAH) reduces the effectiveness of measles vaccination through immunotoxicity to innate and adaptive immune cells

Measles vaccine administered to 9 months until 2 years old toddlers to prevent measles disease. Arround 10% of the total population who received vaccination were still not immune to the measles virus infection. Polycyclic Aromatic Hydrocarbons (PAHs) is an affect factor and also known as an immunotoxic compound, even the effect of PAH exposure to the virus resistance post-vaccination remains elusive. This study was aimed to determine the effect of PAH exposure on the development of effector cells of the immune system after measles vaccination. Balb/c mice were exposed to PAH Benzo[a]pyrene (BaP) dose of 20 mg/kg body weight after injected by the measles vaccine dose of 20 mg/kg body weight. The immune cells was isolated from spleen and analyzed using flow cytometry. The BaP reduced innate and adaptive immune system reactivity towards vaccines. BaP injection after vaccination gave immunotoxic effect on NK cells by reduce the relative number of NK cells. Moreover, BaP gave cytotoxicity on CD4 T cells represented by decreasing CD4 T cell relative number and followed by an increasing of the relative number of CD8 T cells implicated in a low ratio of CD4: CD8 T cells population. Impaired NK and CD4 T cell proliferation during vaccination could reduce the immune response in forming a defense system against secondary infections. Therefore, the failure of measles vaccination may be caused by BaP administration that disrupt effector cell development.