Immunohistochemical detection of retinoic acid receptor alpha in human skin: a comparison of different fixation protocols.

A technique for the immunohistochemical detection of retinoic acid receptor alpha in cryostat sections of normal human skin in situ has been developed. A highly specific mouse monoclonal antibody, directed against the F region of retinoic acid receptor alpha, was used and a panel of 10 fixation protocols investigated. A three-step protocol, consisting of sequential fixation in 3.7% paraformaldehyde, methanol and acetone, revealed strong nuclear immunoreactivity in epidermal keratinocytes and other cell types present in normal human skin. Other fixation protocols, including fixation regimens using formaldehyde or Carnoy's solution, were less suitable or unsuitable for detection of the receptor in cryostat sections of human skin.