Improving chimaerism quantification in bone marrow transplant recipients by image processing and analysis after...

Restriction endonuclease in situ digestion (REISD) with Sau3A of human metaphase chromosomes and interphase nuclei produces a conspicuous banding pattern involving pericentromeric regions of chromosomes 9 and 3. Constitutive heterochromatin of chromosome 9 is never digested by this enzyme while that of chromosome 3 is polymorphic, giving rise to three possible karyotypes: homozygous digested (3--), homozygous undigested (3++) or heterozygous individuals (3+-). Discrimination of this polymorphism between donor and recipient cells constitutes a rapid sex-independent method to monitor quantitatively the chimaerism achieved after bone marrow transplantation. An image processing and analysis (IPA)-assisted procedure which resolves residual fluorescent regions in metaphase chromosomes or interphase nuclei after REISD has been developed. IPA-REISD has interesting advantages over the basic REISD method by allowing a rapid, objective and precise discrimination of the polymorphism in large cell samples.