Adipose tissues as an ancestral immune organ:: Site-specific change in obesity

Close relationships have been demonstrated between adipose tissue and the inflammatory/immune system. Furthermore, obesity is increasingly considered as a state of chronic inflammation. Cytofluorometric analysis reveals the presence of significant levels of lymphocytes in the stroma-vascular fraction of white adipose tissues. In epididymal (EPI) fat, lymphocytes display an "ancestral" immune system phenotype (up to 70% of natural killer (NK), gamma delta(+) T and NKT cells among all lymphocytes) whereas the inguinal (ING) immune system presents more adaptive characteristics (high levels of alpha beta(+) T and B cells). The percentage of NK cells in EPI fat was decreased in obese mice fed with a high-fat diet, whereas 76 positive cells were significantly increased in ING fat. These data support the notion that adipose tissue may elaborate immunological mechanisms to regulate its functions which might be altered in obesity. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.