Development and evaluation of a sandwich ELISA method for the detection of human CD306

Development of a Sensitive Luciferase-Based Sandwich ELISA System for the Detection of Human Extracellular Matrix 1 Protein

Enzyme-linked immunosorbent assay (ELISA) has been one of the main methods for detecting an antigen in an aqueous sample for more than four decades. Nowadays, one of the biggest concerns for ELISA is still how to improve the sensitivity of the assay, and the luciferase-luciferin reaction system has been noticed as a new detection method with high sensitivity. In this study, a luciferin-luciferase reaction system was used as the detection method for a sandwich ELISA system. It was shown that this new system led to an increase in the detection sensitivity of at least two times when compared with the traditional horseradish peroxidase (HRP) detection method. Lastly, the serum levels of the human extracellular matrix 1 protein of breast cancer patients were determined by the new system, which were overall similar to the HRP chemiluminescent system. Furthermore, this new luciferase reporter can be implemented into other ELISA systems for the purpose of increasing the assay sensitivity.

Development and evaluation of a double antibody sandwich ELISA for the detection of human sDC-SIGN

sDC-SIGN is the soluble form of dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN, CD209), which is a molecule involved with pathogen recognition and immune regulation. However, there is no commercially available ELISA kit for detecting human sDC-SIGN, and the normal range of this molecule is unknown. Here, we describe an ELISA for detecting human sDC-SIGN with high specificity. First, sDC-SIGN protein was expressed and purified. Monoclonal and polyclonal antibodies were then raised against the purified protein and subsequently characterized. A sandwich ELISA was developed using polyclonal antibodies specific for sDC-SIGN for capture and a biotin-labeled monoclonal antibody specific for sDC-SIGN for detection of protein. This method has sensitivity up to 0.2 ng/ml. Using this ELISA, we found that the concentration of sDC-SIGN in sera of healthy volunteers ranges from 0-319 ng/ml with a mean concentration of 27.14 ng/ml. Interestingly, the concentration of sDC-SIGN in sera from patients with cancer or chronic hepatitis B virus (CHB) infection was lower than that of health controls. The mean concentrations of sDC-SIGN in cancer patients and chronic hepatitis B virus infection patients were 3.2 ng/ml and 3.8 ng/ml, respectively. We developed a sandwich ELISA for detecting human sDC-SIGN and demonstrated its use by assessing sera concentrations of sDC-SIGN in patients with cancer and chronic CHB infection compared to that of healthy controls.