Why in an immunostaining procedure for a specific antigen do

Why in an immunostaining procedure for a specific antigen, do you normally use two antibodies sequentially?

Solution

In immunostaining methods, usually two types of antibodies are used for detection of specific antigen/protein.

Primary antibody which is specific for the target antigen binds to the antigen. Secondary antibody (labelled with enzyme or a flourophore) is then used for detecting the primary antibody. Here, secondary antibody functions for visualizing the bound primary antibody.

Note: In some immunostaining methods, primary antibody has been directly labelled with flourophore. But most of immunostaining uses two antibodies sequentially.

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