Cell-mediated immunity in the chicken as affected by mercury

Delayed hypersensitivity to phytohemagglutinin and the splenomegaly assay, which is a graft-versus-host response, are accepted indicators of cell-mediated immunity in the chicken. These responses were assessed in chicks that had received either chronic (300 ppm Hg in the drinking water) or acute (five injections of 3 or 12 mg Hg/kg body weight) Hg treatments. Neither of the cell-mediated responses was affected significantly (less than or equal to .05) by the Hg treatments. This contrasts with previous work in our laboratory, which showed that chronic but not acute Hg treatments suppressed humoral immune responses. Cell-mediated immune responses in the chicken are apparently not as susceptible to the toxic effects of Hg as are humoral immune responses.