Cytokines are the most important factors in pathogenesis of infectious, allergic, autoimmune, lymphoproliferative diseases and immunopathological processes. Many cytokines are very useful therapeutic targets for immunodiagnostics of different human diseases. Measurement of the cytokine levels by immunochemical methods in various biological fluids is usually used for diagnostic evaluation. Content analysis of research articles from two Russian immunological journals, “Meditsinskaya Immunologiya” = “Medical Immunology (Russia)” and “Infektsiya i immunitet” = “Russian Journal of Infection and Immunity,”, shows that ELISA, xMAP multiplex immunoassay, and CBA technologies are the most common methods used in clinical and immunological studies aimed for determination of cytokine contents in blood serum/plasma. Normal ranges of some plasma/serum cytokines in healthy individuals were subject to wide variations when using different methods and specific reagents from various manufacturers. The normal ranges applied by the CBA-technology, are significantly higher than appropriate values obtained by ELISA or xMAP-technologies. Most studies included a small control group, usually limited by 15-20 persons. In most of these works, blood serum samples were used for assays, whereas EDTA-conserved plasma was taken only in few studies. It has been concluded that the results of cytokine measurements in blood serum/plasma in healthy individuals vary in wide ranges, and depend on many factors, e.g., initial sampling material, mode of technology, type of test systems, and characteristics of the group under study: number of patients, age, gender, geographical factor, etc. The mentioned data demonstrate a need for large-scale multicenter clinical studies, in order to standardize measurements of the cytokine levels in human peripheral blood and to specify their normal values.
