Is it possible to double label using two antibodies from the same animal source?
Yes, there are ways to do this. One is by using Protein G or Protein A conjugates with different particle sizes. The procedure would be: first incubate with primary antibody I, detect this with Protein A (or G) with the smaller particle size. Then incorporate an incubation with excess free Protein A or G (50-100 µg/ml). This will block practically all binding sites for Protein A or G. Next, incubate for the second antigen with primary antibody II and detect this with the larger sized Protein A or G gold conjugate. A second possibility is to use one-step incubations with a mix of primary antibodies, each labeled directly with a different gold particle size. Custom labeling services are available.
