Revisiting the dilution factor as vital parameter for sensitivity of ELISA assay in CSF and Plasma.

Background: Enzyme Linked Immunosorbent Assay (ELISA) is very sensitive assay which provides quantitative data about expression of antigens. However, its utility is based on certain parameters which vary in the experimental situations. Purpose: We aimed to analyse the dilution factor as an important parameter for determining the sensitivity of ELISA in human samples. Methods: Total of n = 57 ALS patients and n = 48 normal controls were selected for the study. All the patients were recruited from, Department for Neurology and Anaesthesia, PGIMER. Blood and CSF sample was collected and ELISA run was performed in both plasma and blood sample. ELISA of OPTN and TDP-43 was employed to check the respective protein concentration in CSF and Plasma. Results: There was no significant difference which was reported for Plasma as well as CSF values of TDP-43 and OPTN. Dilution test prior to actual experiment made a significant impact in deciding the actual concentration of sample and led to overshootingbeyond range of reference protein. Conclusion: Negative results from our study highlights the significance of determining the dilution factor as an important parameter for conduct of ELISA.