In ELISA ,if we use human serum ,IS serum consider as primary or secondary antibodies?

Question

the research is quantitive detection of human TGF B3 in the serum by indirct ELISA procedure

Answer 1

Think of an ELISA as a sandwich with three layers.  The antigen adheres to the plastic plate.  The primary antibody adheres to the antigen.  The secondary antibody adheres to the primary antibody.  So, the human serum would be the primary antibody (adhering to the antigen).  A secondary antibody would be used to detect whether or not the primary antibody adhered.  The secondary antibody would be something like a mouse anti-human antibody or a rabbit anti-human antibody and would have an enzyme attached to it that is detected with a chemical reagent at the end of all of the incubations.  So, the sandwich would be (from the top down to the well in the plastic dish):

mouse anti-human antibody (with enzyme attached)

human serum (contains antibody against your antigen)

antigen (your antigen of interest)

plastic well