Modification of blood-based (IgG) to salivary-based (IgA) ELISA for Inflammatory Bowel Disease Diagnostic: Tumor necrosis factor (TNF) alpha quantification

Approximately 1.6 million people in the United States are struggling with Inflammatory bowel disease. Even though there are a number of diagnostic tools present, including MRI, CT scan, and laboratory tests, the public still lacks access to diagnostic tools due to their expensive costs and needs for the labor of trained phlebotomists. In response, this study focused on modification from blood based enzyme-linked immunoassay (ELISA) to salivary based ELISA in order to expand its accessibility. A 1mL saliva sample was spiked with 1 ± 0.01 μg/mL lyophilized IgG TNFα proteins, and the unspiked saliva was used as a control to test the modified diagnostic. Saliva samples were processed through centrifugation and syringe filtration steps. The change in color between a serum and salivary ELISA kit using either centrifugation or syringe filtration steps was measured by a Color Analysis app that compared red, green and blue values and a microtiter plate reader. The new protocol of salivary-based ELISA lost sensitivity from 31.5pg/mL to 15.6pg/mL of TNFα protein concentration. The best centrifugation method was when a combination of stock saliva and buffer was used before spiking the sample. This means that we can modify the current serum based diagnostic tool to a salivary diagnostic using centrifugation to filter the sample and implement it in developing countries due to its lower cost.