ELISA in Practice 

Recorded by: Dr. Fardous El-Senduny
Filmed by: Demonstrator Ayman Elsayed
Alpha-fetoprotein (AFP):
 It is synthesized by hepatocytes and endodermally derived gastrointestinal tissues
 It is an oncofetal antigen and a glycoprotein
 It is used for Hepatocellular carcinoma and non- seminomatous testicular tumour.
 The upper limit of normal for a healthy, non-pregnant adult is less than 25 ng/ml
 Elevated levels are also seen in hepatitis, inflammatory bowel disease, cirrhosis.
 It is used in Quad screen (measurement of 4 parameters in 18 weeks gestation) 2nd trimester pregnancy (AFP, hGC, Estriol, inhibin-A).
 The AFP concentration reflects tumour size so AFP correlates with stage and prognosis of disease
Sandwich ELISA:
 An antibody to a target protein is immobilized on the surface of microplate wells and incubated first with the target protein and then with another target protein-specific antibody, which is labeled with an enzyme.
 After washing, the activity of the microplate well-bound enzyme is measured.
 The immobilized antibody (orange) and the enzyme-labeled antibody (green) must recognize different epitopes of the target protein.