Effects of dietary essential fatty acid deficiency on the development of the rat thymus and immune system.

The paper describes an effect of essential fatty acid (EFA) deficiency on the development of the rat thymus and pups' immune system. From birth until being weaned (22nd day), the pups were hand-fed artificial milk diets containing a low (EFA-D) or high (EFA-R) proportion of EFA in the lipid fraction. The weight parameters of the body, thymus and spleen, the fatty acid composition of the individual thymus phospholipid subclasses, and mitogen-induced proliferation of thymus and spleen lymphocytes were studied. The results show that the total body weight of the EFA-deficient (EFA-D) fed animals was significantly decreased in comparison with the EFA-rich (EFA-R) and rat milk hand-fed animals. For the EFA-D group of young rats a high level of the (n-9) and (n-7) series fatty acids [mainly oleic 18:1(n-9) and eicosatrienoic 20:3(n-9) acids] was characteristic of the fatty acids in phosphatidylcholine and phosphatidylethanolamine in the thymus, compensating for the reduction of the content of arachidonic acid 20:4(n-6). The biochemical index of the EFA nutritional deficit in the thymus tissue was observable as early as on day 7. The mitogen-induced (Con A) proliferation of the thymus and spleen lymphocytes was decreased both on the 30th and 40th day of life. The results show that the EFA nutritional deficit in the early postnatal period caused damage to the structure of thymus in the young rats, most probably as a result of the change in the composition of the lipid fraction. These changes also affected the development of the immune system of the whole organism.