*2.1.3. Eosinophils and mast cells*

To maintain the M2 polarization of WAT- residents macrophages, a constant production of IL-4 is necessary. It is speculated that the eosinophils present in the WAT are the main source [8, 10, 12]. Studies in normal weight mice showed that there are a lot of infiltrated eosinophils, which are a major source of IL-4. Moreover, their amount decreased in obese mice no matter what the origin is (genetic as ob/ob or high fat diet) [8, 10, 12], however, there are no reports in humans. Mast cells unlike eosinophils, increases their number in WAT of humans with diabetes mellitus type 2 or obesity, there are reports in fed mice with high fat diet, linking these cells with an increasing adiposity and insulin resistance [8, 10].
