Successful DNA typing after rape is limited when only a few sperm and numerous vaginal cells are recovered from a swab, resulting in an extremely unfavorable ratio of male to female DNA. The goal of this study was to develop a protocol involving sperm cell sorting with flow cytometry based on differences in ploidy, major histocompatibility (MHC) class I, CD45 and cytokeratin expression.
Vaginal lavages were mixed with serially diluted ejaculate. After immunostaining and stoichiometric nuclear staining, spermatocytes were isolated by fluorescence-activated cell sorting. All sorted cells were used for DNA extraction and subsequent quantitative fluorescent multiplex polymerase chain reaction. The preferential lysis was performed for comparison.
The sorting procedure was superior to the preferential lysis method within all tested dilutions. One documented case of rape was examined with both procedures and only after cell sorting with flow cytometry was the male DNA identified.
We were able to show that separation of sperm and vaginal cells using cell sorting with flow cytometry may be crucial when there is only a few sperm detectable after rape.
Useful keywords (using NLM MeSH Indexing)
Electrophoresis, Polyacrylamide Gel
Genes, MHC Class I/immunology
Polymerase Chain Reaction
Sensitivity and Specificity
Find related publications in this database (Keywords)DNA typing