A Focus on Fixation, Van der Loos
Fixatives can be crosslinking like formalin or coagulating like acetone. Crosslinkers conceal antigens, requiring epitope retrieval. Coagulants preserve antigens. Longer fixation reduces staining but signal amplification can help. Cryostat sections are not a "gold standard" since proteins are lost during post-fixation. Formalin-fixed paraffin sections retain proteins better. Terminology should distinguish staining sections vs intact cells. Test antibodies on intact cells and cell blocks before staining tissues. Fixation impacts epitope availability so optimal protocols must be determined empirically. Cell blocks can provide controls when differential staining is not possible.