Question

Which of the following is a key difference between primary and secondary immunofluorescence? Select one: a. Primary immunofluorescence (but not secondary) uses a form of light microscopy to excite the fluorophore b. More than one of the listed characteristics are key differences between primary and secondary immunofluorescence c. Secondary immunofluoresence (but not primary immunofluorescence) is used when more than one antigen needs to be stained d. In primary immunofluorescence the antibody that recognizes the epitope of the antigen is also the one covalently linked to the fluorophore e. Secondary immunofluoresence (but not primary) requires covalently bound fluorophores

Answer 1

(d) In primary immunofluorescence the antibody that recognises the epitope of the antigen is also the one covalently linked with the fluorophore

In primary/direct immunofluorescence, the primary antibody is the only antibody used for udentification of the antigen and is labelled with the fluorophore.

In secondary/indirect immunofluorescence, two antibodies are used for detection of the antigen - primary and secondary. The primary antibodies are unlabelled, while the secondary antibodies are labelled with the fluorophore which binds to the primary antibodies.