Combined immunophenotyping and in situ hybridization (FICTION): a rapid method to study cell lineage involvement in myelodysplastic syndromes

Summary. We present a study in which we used a recently described method combining fluorescence in situ hybridization (FISH) and immunophenotyping, i.e. FICTION, to assess the involvement of different cell lineages in myelodysplastic syndrome (MDS) with monosomy 7 (–7), trisomy 8 (+8) or loss of Y chromosome (–Y). Blood or marrow smears or cytocentrifuge preparations were stained both by antibodies to granulocytes (CD₁₅), monocytes (CD₁₄), T lymphocytes (CD₃), B lymphocytes (CD₂o) and by probes specific for chromosomes 7, 8 or Y. Of nine cases of MDS with –7, four with +8 and two with – Y studied, none showed lymphocytic involvement by the chromosome abnormality. In contrast, -7,-1-8 and – Y were found in granulocytes and monocytes in all patients studied, but they involved a variable proportion of those cells. The partial involvement by –7 and +8 seen in some cases suggests that myelopoi'esis was only partially clonal in those cases, or that the chromosome abnormality was a secondary event in the MDS process. FICTION therefore appears to be a simple and easily reproducible method that can be used for the assessment of lineage involvement in MDS and other haematological malignancies.