A simple mathematical model of cytokine capture using a hemoadsorption device.

Sepsis is a systemic response to infection characterized by increased production of inflammatory mediators including cytokines. Increased production of cytokines such as interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor (TNF) can have deleterious effects. Removal of cytokines via adsorption onto porous polymer substrates using an extracorporeal device may be a potential therapy for sepsis. We are developing a cytokine adsorption device (CAD) containing microporous polymer beads that will be used to decrease circulating levels of IL-6, TNF, and IL-10. In this paper we present a mathematical model of cytokine adsorption within such a device. The model accounts for macroscale transport through the device and internal diffusion and adsorption within the microporous beads. The analysis results in a simple analytic expression for the removal rate of individual cytokines that depends on a single cytokine-polymer specific parameter, Gamma( i ). This model was fit to experimental data and the value of Gamma( i ) was determined via nonlinear regression for IL-6, TNF, and IL-10. The model agreed well with the experimental data on the time course of cytokine removal. The model of the CAD and the values of Gamma( i ) will be applied in mathematical models of the inflammatory process and treatment of patients with sepsis.