Immunohistochemical staining as a potential method for the identification of vaginal epithelial cells in forensic casework

There is currently no accurate method to identify vaginal epithelial cells uniquely. This study aimed to use a cell extraction procedure compatible with routine forensic sampling methods, and to investigate the expression of cytokeratin (CK), estrogen receptor-alpha (ERalpha), and phosphodiesterase 5 (PDE5) in order to distinguish between skin, buccal, vaginal, and external penile epithelial cells. Seminal fluid samples were also examined. Epithelial cell samples were fixed in formalin, embedded in agarose, and processed using histological methods. Antigen-antibody reactions were detected using the DAKO Envision+ detection system. CK was present in all cells from all five sources confirming the origin of cells as epithelial. Both ERalpha and PDE5 positively labeled vaginal, buccal, and skin epithelial cells. Although an antigen unique to vaginal epithelial cells was not identified, we have described a cell extraction procedure for use in the immunohistochemical detection of a wide range of antigens, an approach compatible with forensic diagnostics.