The inflammatory response in incubated human omental adipose tissue is primarily in nonfat cells and independent of collagenase digestion. Explants of human omental adipose tissue were taken for mRNA extraction either at the start or end of 2 h incubation while the values for fat cells and nonfat cells were obtained after a 2 h incubation of adipose tissue with collagenase. The values are based on 6-8 experiments from as many different individuals and shown as the mean ± SEM of the ratios of mRNA relative to that of cyclophilin A [log2 scale]. Statistically significant changes in tissue samples at 2 h, fat cell and nonfat cells as compared to unincubated tissue (to) are indicated as follows: * P < 0.05 and ** P < 0.025. The differences between fat cells and non-fat cells were statistically significant (P < 0.05) for TNFα, IL-1β, IL-8 and omentin.