title: Immunotoxicological effects of benzene inhalation in male Sprague-Dawley rats.
abstract: The inhalation of benzene is toxic to various components of the immunologic system in rodents. Spleen and thymus weights, total spleen and femur marrow cell counts, enumeration of spleen B- and T-lymphocytes, and an assessment of humoral immunocompetence, were used to evaluate the immunotoxicity of benzene in male Sprague-Dawley rats. Rats were exposed to 0, 30, 200 or 400 ppm benzene for 6 h/day, 5 days/week for 2 or 4 weeks. An early indicator of immunotoxicity was a reduction in the number of B-lymphocytes after 2 weeks of 400 ppm. After 4 weeks of 400 ppm, there was a reduction in thymus weight and spleen B-, CD4+/CD5+ and CD5+ T-lymphocytes. Rats exposed to 30, 200 or 400 ppm benzene for 2 or 4 weeks and challenged with sheep red blood cells developed a humoral response comparable to that of the control (0 ppm) animals. Enumeration of spleen T- and B-lymphocytes in rats exposed to benzene and challenged with SRBC showed only a transient reduction in spleen B-lymphocytes after 2 weeks of exposure to 400 ppm. These data suggest that there are no immunotoxicological effects of exposure to 200 ppm benzene or less, in rats exposed for 6 h/day, 5 days/week for 2 or 4 weeks.
authors.affiliation: Chemical Industry Institute of Toxicology, Research Triangle Park, NC 27709-2137, USA. srobinson@speedy.jcrt.harvard.edu
authors.forename: S N
authors.initials: SN
authors.lastname: Robinson
authors.forename: R
authors.initials: R
authors.lastname: Shah
authors.forename: B A
authors.initials: BA
authors.lastname: Wong
authors.forename: V A
authors.initials: VA
authors.lastname: Wong
authors.forename: G M
authors.initials: GM
authors.lastname: Farris
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects; D001554:Benzene / Q000008:administration & dosage / Q000633:toxicity*; D001835:Body Weight / Q000187:drug effects; D001853:Bone Marrow / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D007107:Immune System / Q000187:drug effects*; D007075:Immunoglobulin M / Q000097:blood; D018655:Lymphocyte Count; D008297:Male; D019055:No-Observed-Adverse-Effect Level; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013154:Spleen / Q000187:drug effects; D013601:T-Lymphocytes / Q000187:drug effects
chemical_list: D007075:Immunoglobulin M; D001554:Benzene