Soy Isoflavones have estrogenic activity and are
widely used in human and animal diets. They have many useful activities in
vitro and in vivo. However, Evidence is emerging that dietary isoflavones have
an effect on immune system. The objectives of this study was to determine the
effect of soy isoflavones on some cellular immunological parameters including
through estimation of their effect on daily food intake, daily body weight
gain, splenic and thymic weights, total and differential leukocytic count (TLC
& DLC), IL-6 and histopathology of both thymus and spleen. A total of 30
ovariectomized female Albino rats were divided into three groups (10 females /
group). Control group (C) received phytoestrogen-free casein-based diet, low
soy phytoestrogens group (LF) received low phytoestrogens diet containing (7%
soybeans) and high soy phytoestrogens (HF) group received high phytoestrogens
diet containing (26% soybeans) for 30 days. The results revealed that dietary
phytoestrogens didn't alter daily food intake while reduced daily body weight
gain significantly (P<0.05) in HF group than LF and control group. Splenic
relative weight showed non-significant difference between groups while Thymus
relative weight was significantly (P<0.05) reduced in LF and HF groups than
control in a dose depending manner. Total leukocytic count was significantly
(P<0.05) increased in LF and HF groups than control while DLC showed
non-significant difference among groups. Inteleukin-6 was significantly
(P<0.05) reduced in both treated groups than control. The histopathological
studies of treated groups showed decreased white pulp (WP) area and cellularity
with reduced number of lymphocytes especially in HF group with depletion in
medullary area of thymus in LF group and apoptotic lymphocytes in HF group.
These findings show that dietary phytoestrogens interfere with cellular mediated
immunity in ovariectomized female rats, so they
could alleviate autoimmune diseases manifestations.