QUANTITATIVE IMMUNOCYTOFLUOROMETRY - NEW PARAMETERS FOR THE DEFINITION OF LEUKEMIA-CELLS

In our study we used for definition of leukemia/lymphoma cells a new p arameter which allows the enumeration of mean fluorescence intensity e xpressed by the number of antigen molecules per cell. Quantitative imm unofluorescence using calibration microbeads was performed in 36 patie nts with different acute and chronic lymphoid and myeloid leukemia and in 19 healthy volunteers. We showed that quantitative immunophenotypi ng allowed the definition of aberrant marker densities on neoplastic c ells. We demonstrated under-and overexpression of CD8 marker in CD3/CD 4/CD8 complex in T acute lymphatic leukemia and T non-Hodgkin's lympho ma and T leukemia of large granular lymphocytes as compared to normal counterparts. We pointed out that certain antigens (e. g. CD10, CD4, C D24) were expressed at different levels on different cell subsets (CD1 0 in early B-acute lymphatic leukemia and coexpressed in T-acute lymph atic leukemia, CD4 on T cells and monocytes, CD24 on B cells and granu locytes in chronic myeloid leukemia). We showed that quantitative immu ne fluorescence could provide new data contributing to a more precise definition of cell differentiation. We documented the significant diff erence between antigen density of early and late markers in B-cell and myeloid malignancies. Further, we demonstrated that quantitative immu ne phenotyping could help in determination of exact definition of path ologic clone in morphologically immature leukemia population and showe d that parameters of this method are also convenient for cytoplasmic m arker evaluation. In our study we were able to demonstrate that CD45 q uantitative expression appeared to be a more informative parameter tha n its percentage of antigen-positive cells as a measure of antigen exp ression only and we pointed out that low and high CD45 densities enabl ed to differentiate between pathological clone and residual healthy po pulation in examined sample. We showed that quantitative immune phenot yping could be another important parameter for definition of leukemia phenotype suitable for detection of minimal residual disease.