I have a question about blocking the culture in immunofluorescence staining which is done prior to the addition of the stain-bound secondary antibody. I do not understand what blocking does. In one reference I read it that adding the blocking solution actually blocks the large plasma proteins that may cause background staining. Another reference said that blocking is done to block those IgG antibodies that may be present in the culture and are against the animal in which the secondary antibody was raised. I'm really confused.
