COMBINED IMMUNOPHENOTYPING AND IN-SITU HYBRIDIZATION (FICTION) - A RAPID METHOD TO STUDY CELL LINEAGE INVOLVEMENT IN MYELODYSPLASTIC SYNDROMES

We present a study in which we used a recently described method combin ing fluorescence in situ hybridization (FISH) and immunophenotyping, i .e. FICTION, to assess the involvement of different cell lineages in m yelodysplastic syndrome (MDS) with monosomy 7 (-7), trisomy 8 (+8) or loss of Y chromosome (-Y), Blood or marrow smears or cytocentrifuge pr eparations were stained both by antibodies to granulocytes (CD15), mon ocytes (CD14), T lymphocytes (CD3), B lymphocytes (CD20) and by probes specific for chromosomes 7, 8 or Y. Of nine cases of MDS with -7, fou r with +8 and two with -Y studied, none showed lymphocytic involvement by the chromosome abnormality. In contrast, -7, +8 and -Y were found in granulocytes and monocytes in all patients studied, but they involv ed a variable proportion of those cells. The partial involvement by -7 and +8 seen in some cases suggests that myelopoiiesis was only partia lly clonal in those cases, or that the chromosome abnormality was a se condary event in the MDS process. FICTION therefore appears to be a si mple and easily reproducible method that can be used for the assessmen t of lineage involvement in MDS and other haematological malignancies.