Abstract:
This doctoral thesis describes a newly developed method for the identification of mucous cells in forensic traces by means of immunocytochemical staining.
Among the variety of cytokeratins that exist in human cells, it was possible to find a few which were specific for mucosa. Subsequently, existing immunohistochemical staining protocols which were initially designed for tissue sections were modified for use on cytological preparations. In addition, suitable procedures for fixation and permeabilization had to be found and adjusted.
In a large number of preliminary tests, cytokeratin 4 (CK4) emerged as a cell component specific for mucous cells suitable for forensic use.
In CytoRich Red a suitable fixation solution could be found. The use of trypsin for permeabilization resulted in excellent staining results without compromising the morphological integrity of the cells.
By means of the developed staining method, it was possible for the first time to reliably identify human mucous cells in forensic samples.
As a next step, those cells that were stained according to the newly developed protocols could be obtained via laser microdissection. In a number of sample tests, it was possible to realise a DNA-typing from the thus obtained cells.
Finally, differences in the relative expression of cytokeratin 4 between vaginal and buccal mucosa could be found via real-time quantitative PCR. This approach constitutes a first step towards a clear distinction of the two kinds of mucosa, which can added to the mosaic of forensic trace analysis.