We studied whether feeding pregnant female rats a 15% olive-oil diet affects the activity of lymph cells in the spleen and tumors in offspring with chemically-induced colon tumors. Rat mothers were fed either a 7% corn-oil or a 15% olive-oil diet. Five-week-old male offspring were divided into 3 groups. A control group was fed the 7% corn-oil diet similar to their mothers. The experimental group I was fed the 7% corn-oil diet whereas their mothers were fed the 15% olive-oil diet. The experimental group II was fed the same 15% olive-oil diet as their mothers. Experimental rats were injected weekly for 8 weeks with the carcinogen, 1,2-dimethylhydrazine (DMH), 20 mg/kg b.w. Results of experiments were studied 6 months later. The area of zones in the spleen responsible for producing B and T lymphocytes were measured and the number of cells counted. The activity of lymphoid elements of the spleen and of tumors were studied using immunohistochemical methods for evaluating the synthesis of CD8+ lymphocytes and proliferative activity of lymphocytes in spleens and tumors. Feeding pregnant or lactating mothers with the 15% olive-oil diet had no marked tumor-protective effect on chemically-induced colon cancer in offspring. Diet-dependent changes were found at the cellular level. In the spleen of control offspring, the presence of a tumor was accompanied by an increase in the number of Ki-67+ cells and CD8+ lymphocytes in the red pulp. In experimental group I, DMH significantly increased the total cell number and the number of CD8+ lymphocytes in the red pulp of the spleen in both tumor-bearing and tumor-free rats. In experimental group II, the total number of lymph cells and the number of CD8+ lymphocytes increased compared to offspring fed a control diet. Tumor formation activated the proliferative activity of lymph elements. The total number of cells in infiltrates of the colon mucosa decreased in tumor-bearing rats compared to tumor-free counterparts, and this was seen in all three dietary groups of rats. In tumors from offspring of experimental group II, only the number of CD8+ lymphocytes increased compared to those in offspring of experimental group I. The findings indicate that feeding mothers the 15% olive-oil diet had a cancer-inhibiting role in offspring, predominately changes at the cellular level.

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