PCB-induced suppression of the humoral and cell-mediated immunity in guinea pigs

Abstract

The effect of PCB feeding at levels of 0, 10, 50 and 250 ppm, on the humoral and cell-mediated immune response is described. Three experiments were carried out with guinea pigs. A suppression of the humoral immunity, after stimulation with one dose of tetanus toxoid (alum-adsorbed) was found at the 50 ppm level.The antitoxin titres were statistically significantly decreased as determined with the passive haemagglutination test. Also, the number of tetanus antitoxin-producing cells in the stimulated popliteal lymph nodes were reduced, as was shown with the indirect fluorescent antibody technique. In a second experiment, animals were immunized with two doses of tetanus toxoid. A decreased immunological response was observed again at the 50 ppm level using single radial immuno-diffusion and fluorescent anti-body techniques. In addition lymphopenia was found. In the third experiment the cell-mediated immunity was stimulated with Freund's Complete Adjuvant. The skin reactions after tuberculination, as a parameter of the cell-mediated immunity, were statistically significantly reduced at the 50 ppm level. In all 3 experiments, organ weights were recorded and histological studies were performed. Stress was not considered responsible for the reduced immunological responses. A high mortality occurred at the 250 ppm level. Cachexia and depletion of the lymphoid system and liver damage were the most important findings in these animals. PCB contents of pooled liver samples are given.