Please find the link for the following protocol:
HUMAN INTERLEUKIN 4 ENZYME IMMUNOASSAY PROCEDURE
INTRODUCTION AND PRINCIPLE OF TEST
Interleukin 4 (IL-4, B-cell growth factor-1, BSF-1) is a T-cell derived cytokine with a molecular weight of approximately 15 to 19 kD. It plays an important role in theactivation of resting B-cells and the subsequent proliferation and differentiation of Bcells. IL-4 is essential for IgE synthesis in vitro. It was also found to inhibit the secretionof IL-1B, TNF-a, and IL-6 of human monocytes, to down-regulate the surface expressionof CD5 on B-cells, and to promote the growth of human T-cells.
The Human IL-4 ELISA is an enzyme-linked, sandwich immunoassay for the quantitativeand highly sensitive measurement of the human cytokine Interleukin 4 (IL-4) in culture supernatants, plasma, serum, and urine.
Pre-coated murine monoclonal antibodies generated against human IL-4 are used to capture human IL-4 from the sample. The standards and samples are pipetted into the
wells of the plate. IL-4 specific rabbit anti-human polyclonal antibodies then detect the captured IL-4. After incubation, the plate is washed to remove any unbound material. The addition of goat anti-rabbit conjugated alkaline phosphatase, followed by substrate and amplifier solutions provide the basis for the detection system. The products change color in proportion to the amount of IL-4 found in the samples. The absorbances are read
in a microplate reader. A standard curve is obtained by plotting the optical density (absorbance) for each standard versus the corresponding IL-4 concentration. This demonstrates a direct relationship between optical density (OD) and cytokine
concentration: i.e., the higher the OD, the higher the cytokine concentration in the sample.