C. Deheer et al., LYMPHODEPLETION OF THE THYMUS CORTEX IN RATS AFTER SINGLE ORAL INTUBATION OF 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN, Chemosphere, 29(9-11), 1994, pp. 2295-2299
Atrophy of the thymus and thymic lymphodepletion occurs after exposure
to sublethal doses of TCDD. Previous studies using high doses of TCDD
(150 mu g/kg) have indicated a preferential lymphodepletion of the th
ymus 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 mu g/kg) on thymic weights and thymocyte subpopulations i
n Wistar rats on day 4 after exposure. A single administration of 1 mu
g/kg TCDD induced a significant reduction in the number of immature C
D4(+)CD8(+) double-positive (DP) thymocytes. At this time point the nu
mbers of mature CD3(high) medullary thymocytes were not affected at an
y dose level tested. We conclude that also lower dose levels of TCDD i
nduce thymic atrophy via a preferential lymphodepletion of the thymus
cortex.