Biological effects of gestational and lactational PCB exposure in neonatal and juvenile C57BL/6 mice

The purpose of this study was to obtain a better understanding of polychlorinated biphenyl (PCB) immunotoxicity in the developing mouse. Adult female mice were dosed with three subcutaneous injections per week of 50 mg/kg Aroclor 1242 (A1242), Aroclor 1254 (A1254), or corn oil for 2 weeks and then mated with nondosed males. First-litter pups were sacrificed at 7 or 28 days of age. At both ages, the tissue concentration of PCB was significantly higher in both the A1242 and A1254 pups than in oil-treated controls. Seven-day-old pups exposed to A1242 or A1254 had significantly decreased splenic IL-2 production. Alterations in the percentages of T cell subsets compared to controls were observed in A1242-exposed pups; an increased spleen somatic index was noted only in A1254-exposed pups. Twenty-eight-day-old pups exposed to A1254 demonstrated a significant decrease in thymus somatic index, an increase in liver somatic index, a 25% decrease in total circulating T(4), and decreased B cell percentages relative to their controls. Alteration in the percentages of CD3(int) T cells was observed in A1254-exposed 28-day-old pups. A significant increase in 7-ethoxyresorufin- O-deethylase (EROD) and 7-benzoxyresorufin-O-dearylase (BROD) activity was measured at both ages in A1254-exposed pups and in A1242-exposed 28-day-old pups. These data confirm that during gestation and lactation A1242 and A1254 are transferred from dams to pups and that such exposure results in immune-related effects in neonatal (7-day-old) and juvenile (28-day-old) mice. Furthermore, A1254 exposure produces more frequent and pronounced effects than exposure to A1242.