When should I use an isotype-specific secondary antibody?

Isotype-specific antibodies (for example, Goat Anti-Mouse IgG1, Goat Anti-Mouse IgG2a, or Goat Anti-Mouse IgG2b) can be used to specifically detect primary antibodies from the listed sub-class. This can be useful for multiplex detection using multiple mouse monoclonal antibodies that are different isotypes.

Anti-mouse subtype-specific secondary antibodies also can be useful for avoiding background when staining mouse tissues with mouse monoclonal antibodies, because IgG is present at relatively low levels in most mouse tissues.

Isotype-specific antibodies also can be used for identifying the isotype of a monoclonal antibody, or for staining B-cell subsets.