A distinct subset of immune cells, called iNKT cells, which reside long-term in the adipose (fat) tissue of lean people and have anti-inflammatory properties, have been characterized in a study published in Nature Immunology.

In both mice and humans iNKT cells, which recognize specific fat molecules, are enriched in adipose tissues where they play a protective role against obesity-induced inflammation and glucose intolerance. The number of iNKT cells decreases in visceral fat during the development of obesity.

Michael Brenner and colleagues find that adipose tissue iNKT cells express a unique set of genes compared with other previously characterized iNKT cells. Adipose tissue iNKT cells produce the cytokines interleukin 10 and interleukin 2, which allows them to maintain an anti-inflammatory macrophage subset and to control the frequency of regulatory T cells in the lean adipose tissue.

The capacity of iNKT cells to rapidly produce cytokines has previously been used to manipulate the immune response in animal models of autoimmunity and cancer. These findings indicate that they may represent a therapeutic target in obesity and metabolic disorders as well.