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Are Natural Killer Cells Protecting the Metabolically Healthy Obese Patient?
Author(s) -
Lynch Lydia A.,
O'Connell Jean M.,
Kwasnik Anna K.,
Cawood Thomas J.,
O'Farrelly Cliona,
O'Shea Donal B.
Publication year - 2009
Publication title -
obesity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.438
H-Index - 199
eISSN - 1930-739X
pISSN - 1930-7381
DOI - 10.1038/oby.2008.565
Subject(s) - medicine , immune system , cd8 , obesity , immunology , cytotoxic t cell , adverse effect , diabetes mellitus , endocrinology , biology , biochemistry , in vitro
With the emerging obesity pandemic, identifying those who appear to be protected from adverse consequences such as type 2 diabetes and certain malignancies will become important. We propose that the circulating immune system plays a role in the development of these comorbidities. Clinical data and blood samples were collected from 52 patients with severe obesity attending a hospital weight‐management clinic and 11 lean healthy controls. Patients were classified into metabolically “healthy obese” ( n = 26; mean age 42.6 years, mean BMI 46.8 kg/m 2 ) or “unhealthy obese” ( n = 26; mean age 45 years, mean BMI 47.5 kg/m 2 ) groups, based upon standard cutoff points for blood pressure, lipid profile, and fasting glucose. Circulating lymphoid populations and phenotypes were assessed by flow cytometry. Obese patients had significantly less circulating natural killer (NK) and cytotoxic T lymphocytes (CTL) compared to lean controls. There were significantly higher levels of NK cells and CTLs in the healthy obese group compared to the unhealthy obese group (NK: 11.7% vs. 6.5%, P < 0.0001, CD8 13.4% vs. 9.3%, P = 0.04), independent of age and BMI and these NK cells were also less activated in the healthy compared to the unhealthy group (CD69, 4.1% vs. 11.8%, P = 0.03). This is the first time that quantitative differences in the circulating immune system of obese patients with similar BMI but different metabolic profiles have been described. The significantly higher levels of CTLs and NK cells, which express fewer inhibitory molecules, could protect against malignancy, infection, and metabolic disease seen in obesity.