Lipoxin A4 (LXA4) is a biologically active lipoxygenase interaction product derived from arachidonic acid. Arachidonic acid is first oxygenated by 15-lipoxygenase to form 15-HETE which is then converted by 5-lipoxygenase and epoxide hydrase to generate LXA4. LXA4 stimulates leukocyte chemotaxis without aggregation and inhibits natural killer cell cytotoxicity. It also provokes contraction of parenchymal strips and stimulates microvascular changes.
Recent findings indicate that LXA4 inhibits leukocyte-dependent inflammation. Determination of LXA4 level may provide new understanding of the role of LXA4 in basic cellular reactions and in pathophysiology of inflammation and other disease processes.
Principle of the Assay:This is an ELISA (Enzyme-Linked Immunosorbent Assay) for the quantitative analysis of Lipoxin A4 levels in biological fluid. This test kit operates on the basis of competition between the enzyme conjugate and the Lipoxin A4 in the sample for a limited number of antibody binding sites.
First, the diluted antibody is added to the microplate. Then, the sample or standard solution is added to the microplate. Next, the diluted enzyme conjugate is added. The mixture is shaken and incubated at RT for one hour. During the incubation, competition for binding sites is taking place. The plate is then washed removing all the unbound material. The bound enzyme conjugate is detected by the addition of substrate, which generates an optimal color after 30 minutes. Quantitative test results may be obtained by measuring and comparing the absorbance reading of the wells of the samples against the standards with a microplate reader at 650nm. The extent of color development is inversely proportional to the amount of Lipoxin A4 in the sample or standard. For example, the absence of Lipoxin A4 in the sample will result in a bright blue color, whereas the presence of Lipoxin A4 will result in decreased or no color development.
