Combined FISH and Immunolabeling on Paraffin-Embedded Tissue Sections for the Study of Microchimerism

Fluorescence in situ hybridization(FISH) has proven to be a very useful technique for the study of chimerism and microchimerism (2,4). Based on the detection of sexchromosomes, this technique allows for the identification and localization of donor and recipient cells in cases of sex-mismatched transplantation or cells from mothers and their male fetuses in studies of fetomaternal cell trafficking. For the further assessment of chimerism, the combinationof FISH and techniques of protein detection allows for the determination of the phenotype of persistent chimericcells. However, such combined techniques have proven to be difficult to apply to paraffin-embedded tissue specimens, which is the common preparation of tissue samples following biopsy, surgery, or autopsy.