Toxic effects of dietary methylmercury on immune function and hematology in American kestrels (Falco sparverius)

Fifty-nine adult male American kestrels (Falco sparverius) were assigned to one of three diet formulations including 0 (control), 0.6, and 3.9?μg/g (dry wt) methylmercury (MeHg). Kestrels received their diets daily for 13 weeks to assess the effects of dietary MeHg on immunocompetence. Immunotoxic endpoints included assessment of cell-mediated immunity (CMI) using the phytohemagglutinin (PHA) skin-swelling assay and primary and secondary antibody-mediated immune responses (IR) via the sheep red blood cell (SRBC) hemagglutination assay. Select hematology and histology parameters were evaluated to corroborate the results of functional assays and to assess immunosuppression of T and B cell-dependent components in spleen tissue. Kestrels in the 0.6 and 3.9?μg/g MeHg groups exhibited suppression of CMI, including lower PHA stimulation indexes (p?=?0.019) and a 42 to 45% depletion of T cell-dependent splenic lymphoid tissue (p?=?0.006). Kestrels in the 0.6?μg/g group exhibited suppression of the primary IR to SRBCs (p?=?0.014). MeHg did not have a noticeable effect on the secondary IR (p?=?0.166). Elevation of absolute heterophil counts (p?