Analysis of cytokine expression in dermatology

During the past decade, the detection of cytokines has been a focus of scientific interest, including in dermatology. Dysregulation of cytokine production seems to be involved in the pathogenesis of various diseases. The determination of cytokine levels is of increasing diagnostic importance, and cytokines are used as therapeutic agents too. Cytokines are polypeptides secreted by a wide variety of cells in response to diverse stimuli, and mediate autocrine, paracrine, or endocrine effects that are often pleiotropic and redundant. Their molecular weight lies between 6 and 70 kd. The cytokines of immunologic relevance are primarily those that are formed by immune cells (monokines and lymphokines) and/or influence their function. In principle, cytokines are detectable on 3 levels: (1) By using polymerase chain reaction, the messenger RNA expression of cytokine genes can be detected and, with the newer techniques, even quantified. (2) Protein synthesis can be detected by using bioassays and enzyme immunoassays or immunocytologic or immunohistologic detection of intracellular cytokine production. (3) Finally, there are indirect methods for the detection of cytokine formation by analysis of products of cytokine activity. The immunobiological features of cytokines and the different approaches for cytokine determination are briefly discussed herein because basic knowledge of these biologically highly active messenger substances and the capabilities and limits of the individual detection methods are essential for a sensible interpretation of the relevant findings.