Measurement of Cytokines in Peritoneal Fluids

Cytokines are small-molecular-weight proteins that mainly function in soluble, secreted form. Cytokines regulate a wide variety of cellular functions, such as immune responses and the growth and differentiation of hemopoietic, epithelial, and mesenchymal cells (1 ,2 ). Typical features of cytokines are pleiotropy and redundancy, that is, each cytokine has numerous functions, and one function is often mediated by several different cytokines. Based on their functional or structural similarities, cytokines can be roughly divided into interleukins (IL), tumor necrosis factors (TNFs), interferons (IFNs), hemopoietic growth factors, and chemokines. Practically all nucleated cells produce certain cytokines at moderate levels, but a high level of cytokine production is typically a characteristic of the cells of the immune system, particularly of activated monocytes/macrophages and T-lymphocytes.