Histological and histometrical evidences for phenol immunotoxicity in mice

Phenol is a common industrial and ubiquitous environmental chemical which is used to synthesize resins and plastics. Due to its anesthetic and disinfectant properties, phenol is also widely used in pharmaceutical products. Since there were no adequate data about phenol immunotoxicity, the purpose of the present study is to investigate its toxic effects on the histological structures of the lymphoid organs in the mice. A total of 80 mice were randomly distributed into one control group and three experimental groups. The control group received only distilled water, whereas experimental groups were orally administered phenol at the concentrations of 80, 180, and 320 mg/kg/day, respectively. After 28 consecutive days, tissue samples were taken and histological changes of the spleens, thymuses, adrenal glands, and lymph nodes were examined using optical microscopy. The results showed that in the phenol treated animals; splenic megakaryocyte counts increased, the diameter of the splenic follicles decreased, the thymocyte population in both cortex and medulla reduced, the thickness of the reticular layers of adrenal gland increased and lymphatic cells populations in the lymph node were reduced, significantly (P < 0.01). Also, remarkable histological changes were noted in the various lymphatic organs of the treated mice. Overall, present findings give some histological evidences that selected qualitative and quantitative parameters of the lymphatic organs were significantly altered by phenol administration. In conclusion, the significant decreases of the immune cell populations together with histological alterations in the immunocompetent organs of the mice exposed to phenol indicate the immunosuppressive and immunotoxic properties of this chemical material.