ELISA kit is widely used in medical and biological research for detecting and quantifying substances such as antibodies, antigens, proteins, and hormones in samples like blood or serum. It is commonly applied in diagnosing infectious diseases including HIV, hepatitis, and Lyme disease. The kit is also used in food industry testing for allergens and in research settings to study immune responses. Due to its high sensitivity and specificity, ELISA kits are essential in clinical laboratories and drug development for accurate measurement of biomarkers.