Description:
<jats:title>Abstract</jats:title><jats:p><jats:italic>Objective:</jats:italic> Obesity is associated with oxidative stress and inflammation. We hypothesized that the pro‐inflammatory state in obesity may result in spontaneous activation and, hence, increased generation of reactive oxygen species (ROS) and integrin expression in the circulating leukocytes.</jats:p><jats:p><jats:italic>Methods:</jats:italic> Flow cytometry was used to determine integrin expression (immunostaining) as well as superoxide and hydrogen peroxide productions (fluorescent probes) in the peripheral blood and splenic leukocyte of 24‐week‐old male obese normotensive and not‐as‐yet diabetic Zucker rats (<jats:italic>n</jats:italic> = 6) and their lean counterparts (<jats:italic>n</jats:italic> = 6).</jats:p><jats:p><jats:italic>Results:</jats:italic> Obese rats had hyperlipidemia and normal arterial pressure, plasma glucose, and creatinine concentrations. Nevertheless, obese rats exhibited increased hydrogen peroxide production by circulating and splenic CD4+ and CD8+ T lymphocytes and by splenic macrophages. This was accompanied by up‐regulations of CD11a expression in the peripheral blood and splenic CD4+ T cells, CD11b in circulating macrophages, and CD11a and CD18 in circulating granulocytes.</jats:p><jats:p><jats:italic>Conclusion:</jats:italic> The study revealed direct evidence of spontaneous leukocyte activation and increased ROS generation by T lymphocytes and monocytes in the peripheral blood of obese Zucker rats before the development of diabetes or hypertension. These findings illustrate the link between obesity, oxidative stress, and inflammation.</jats:p>