Lymphodepletion of the thymus cortex in rats after single oral intubation of 2,3,7,8-tetrachlorodibenzo-p-dioxin.
Atrophy of the thymus and thymic lymphodepletion occurs after exposure to sublethal doses of TCDD. Previous studies using high doses of TCDD (150 micrograms/kg) have indicated a preferential lymphodepletion of the thymus cortex on day 4 after a single oral intubation. Here we describe the effects of a single oral intubation of lower dose levels of TCDD (1, 5, and 25 micrograms/kg) on thymic weights and thymocyte subpopulations in Wistar rats on day 4 after exposure. A single administration of 1 micrograms/kg TCDD induced a significant reduction in the number of immature CD4+CD8+ double-positive (DP) thymocytes. At this time point the numbers of mature CD3high medullary thymocytes were not affected at any dose level tested. We conclude that also lower dose levels of TCDD induce thymic atrophy via a preferential lymphodepletion of the thymus cortex.
Laboratory for Pathology, National Institute of Public Health and Environmental Protection, Bilthoven, The Netherlands.
C
C
De Heer
H J
HJ
Schuurman
J G
JG
Vos
H
H
Van Loveren
D000284:Administration, Oral; D000818:Animals; D004305:Dose-Response Relationship, Drug; D008231:Lymphopenia / Q000139:chemically induced; D008297:Male; D009929:Organ Size / Q000187:drug effects; D000072317:Polychlorinated Dibenzodioxins / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D013950:Thymus Gland / Q000187:drug effects* / Q000473:pathology
D000072317:Polychlorinated Dibenzodioxins