Particulate air pollution causes abnormal development of immune system of neonates. Previous studies have revealed that maternal exposure to carbon black nanoparticle (CB-NP) disturbs development of the lymphoid tissues. The immune-activation elicited by CB-NP were dependent on the stage of gestation in which they were exposed. Thus, the present study aimed to investigate the effect of CB-NP on neonatal lymphoid tissues depending on the time of exposure during gestation in mice.
Pregnant ICR mice were treated with CB-NP (95 µg/kg/time) by intranasal instillation, in gestational days 4 and 5 (preimplantation period), 8 and 9 (organogenesis period), or 15 and 16 (fetal developmental period). Spleen and thymus were collected from offspring mice at 1-, 3-, and 5-days post-partum. Lymphoid phenotypes were examined by flow cytometry. Gene expression was examined by quantitative RT-PCR.
The numbers of total splenocytes and splenic CD3−B220− phenotype (non-B/non-T cell) of offspring in the postnatal day 5 were significantly increased by the exposure to CB-NP during organogenesis period comparing with no exposure (control), pre-implantation period exposure, and fetal development period exposure. In contrast, expression levels of mRNA associated with chemotaxis and differentiation for immune cells in spleen were not affected by the CB-NP exposure during any gestational period. Overall, the organogenesis period was the most sensitive to CB-NP exposure with regard to lymphoid tissue development. Moreover, repetitive CB-NP exposure across the several gestational periods may be critical causes resulting in the neonatal immunotoxicity.
