Antibody-mediated immunotoxicity in American kestrels (Falco sparverius) exposed to polychlorinated biphenyls

Antibody-mediated immune function in adult and recently fledged (30 to 33 d old) American kestrels (Falco sparverius) was examined in birds exposed di rectly, or only in ovo, to polychlorinated biphenyls (PCBs). In 1998, 9 mat ure male and 9 female kestrels were fed PCBs, whereas 9 females and 10 male s served as controls. A mixture of Aroclors 1248:1254:1260 suspended in saf flower oil was injected into the kestrels' food items, while in control die ts only the same volume of oil was added. The dosage of PCBs was approximat ely 7 mg/kg kestrel/d, beginning in March 1998 and continuing for 120 d. In 1998, the antibody-mediated immune response was stimulated by immunization and booster vaccinations of the kestrels using a nonpathogenic antigen, di nitrophenol-keyhole limpet hemocyanin (DNP-KLH). In 1999, offspring from th ree treatment groups based upon maternal exposure to PCBs were similarly te sted for their antibody response. None of these mothers was vaccinated with DNP-KLH the previous year. The maternal groups were: (1) exposed to PCBs i n 1998 for 120 d, (2) exposed in ovo in 1998 (i.e., mothers were produced b y PCB-exposed parents), or (3) unexposed to PCBs. Serum antibody levels wer e determined using an enzyme-linked immunosorbent assay (ELISA). In 1998, P CB-exposed adult females had a significantly higher antibody response than did controls, whereas adult males exposed to PCBs had significantly suppres sed antibody production. For the nestlings produced in 1999, maternal treat ment significantly affected antibody response. Generally, the antibody resp onse in the nestlings was much lower than that seen in adult kestrels. Yet both male and female offspring from mothers that had been fed PCBs the prev ious year had significantly higher postbooster anti-DNP-KLH titers than con trol and in ovo-exposed maternal groups, thus mimicking the response seen i n the adult females the previous year. These sex-specific responses in PCB- exposed birds provide further evidence of the endocrine-disrupting behavior of PCBs. Both suppression and stimulation of the antibody response are und esirable because this indicates that the immune system is not able to respo nd normally to challenges by infectious or other disease-causing agents.