Fig. 4.

THC-induced thymic atrophy and alteration of T cell subsets persist until birth. Groups of two C57BL/6 pregnant mice (n = 2) were injected on GD16 with 50 mg/kg THC or vehicle. On GD17 (A), GD18 (A–E), and PD1 (A, F–I), the thymi from the fetuses or pups (average 10) from each mother were harvested and pooled. A, viable thymic cellularity was determined by trypan blue dye exclusion. The data represent the mean thymic cellularity per fetus/pup ± S.E.M. B, C, F, and G, the thymocytes were double-stained with FITC-anti-CD4 and PE-anti-CD8 mAbs and analyzed by flow cytometry. Representative dot plots are shown in B and F where the percentage of cells in each subset is depicted on each dot plot. Absolute numbers of cells found in each subset are shown in C and G. D and H, thymocytes were analyzed for apoptosis using TUNEL followed by flow cytometric analysis. The percentage of apoptotic cells is depicted in each histogram. E and I, the thymocytes were analyzed for levels of caspase-3 and caspase-7 activity as described under Materials and Methods. The results are depicted as mean ± S.E.M. A, C, E, G, and I, statistically significant difference between vehicle control and THC treatment group by two-tailed unpaired Student's t test (*, p ≤ 0.05; **, p ≤ 0.01; ***, p ≤ 0.001).