| The term cytokine(CK) is used as a general name for a diverse group of soluble small extracellular proteins or glycoproteins, which are secreted by immune cells and which regulate the functional activities of cells and tissues. The research on cytokines was booming in the past few decades, and so far over 200 different human cytokines have been identified. Cytokines are crucial intercellular regulators and mobilizers, engaged in innate and adaptive inflammatory host defenses, cell growth, differentiation, cell death, angiogenesis, as well as development and repair processes aimed at the restoration of homeostasis. The cytokines are powerful , which act as humoral regulators atnano-concentrations and play an important role in the development and differentiation of the cells as well as in the interactions between cells. Although in some cases cytokines are produced constitutively, usually they are produced by virtually immune cells only in response to injurious stimulis. Cytokines act on cells via their membrane receptors. Finally cytokines have been divided into various family groups based on the structural homologies of their receptors, such as interleukins, interferons, tumor necrosis factor superfamily, chemokines, colony-stimulating factors, and growth factors.Helper 1 and helper 2 T lymphocytes secrete different types of cytokines. At present, it has been confirmed that both cellular immunity (CMI) and humoral immunity in response to antigenic stimuli are induced by these different type cytokines. Generally speaking , Thl—like cytokines include IFN-γ , IL-2, and lymphotoxin(LT), whereas Th2-1 ike cytokines include IL-4, IL-5, IL-6, IL-10, IL—13, and possibly IL—9. Thl—like cytokines are involved in the pathogenisis of delayed type hypersensitivity(DTH) and the activation of macrophages , while Th2-like cytokines promote B lymphocytes proliferation into plasma cells secreting specificity antibodies , therefore enhance the macosal immunity , induce the humoral immunity and I type hypersensitivity. On the other hand, cytokines, including the type 1 and type 2 categories , form a complicated interactive network. Since there is a spectrum of disease severity for many human pathologic conditions, there is likely to be a spectrum of cytokine production and imbalance, or cytokine dysregulation, at different stages of diseases.So detecting different cytokines is an important aspect in clinical and basic research.Magnetic affinity immunoassay(MAIA), which combines enzyme immunoassay with immunomagnetic beads , is found based on employing a pair of monoclonal antibodies recognizing distinct epitopes, together with amplified system of FITC/anti-FITC mAb The quantitative MAIA is well recognized with its stability, sensitivity, reliability, and radioactive-free. What is more, it is easy to perform with less sample needed.In the present study, we first developed a MAIA with two mAbs 4H12 and 1D6 recognizing different epitopes of recombinant human IL-4, labled with fluorescein isothiocyanate (FITC) and alkaline phosphatase (AP) respectively. Then the immunomagnetic beads were coated with anti-FITC mAb. After selecting the different concentration of the two mAbs the MAIA system was optimized with the detectable limitation of IL-4 reaching 10 ng/L. Its specificity was also proved by the cross-reaction test. The recovery, the coefficients of variant (CV) of intra-assay and inter-assay were 99. 4%-103. 9%, 3.0%—4.6% and 3. 2 %—4.0% respectively, which indicated that the MAIA is reproducible. In the next step, sera from healthy adults and some patients were detected, and it was showed that the IL-4 level in patient sera with nephrotic syndrome(NS) was signicantly higher than that in normal control subjects. Furthermore, the IL-4 levels in NS patients were related with the course of disease.By using the same technology, we also set up the MAIA system for detecting TNF. As a result, the detection...
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