6th ESACP Congress, Heidelberg, April 7-11, 1999

A077
DIAGNOSTIC VALUE OF FLOW CYTOMETRIC IMMUNOPHENOTYPING IN B-CHRONIC LYMPHOCYTIC LEUKEMIA - CORRELATION BETWEEN BONE MARROW AND PERIPHERAL BLOOD SAMPLES
Kardum MM, Siftar Z, Nazor A, Kardum-Skelin I*, Jaksic O*, Maric-Besic K*, Jaksic B*

Institute of Clinical Chemistry and *Department of Medicine, University Hospital "MERKUR" Zagreb, Croatia

As the incidence of B-cell chronic lymphocytic leukemia (B-CLL), the most common form of human leukemia, increases in an aging population, it becomes more important to correlate the heterogenity in clinical courses of B-CLL with the determination of the surface membrane marker phenotype of the leukemic B-cells. Results of flow cytometric immunophenotyping of peripheral blood (PB) and bone marrow (BM) samples were compared in a series of B-CLL patients to establish if they match at a sufficiently acceptable level for routine diagnostic purposes.
Design and methods: PB and BM samples of 138 patients with B-CLL (66 females/72 males, median age 62.5 years) were analysed by flow cytometric method on Coulter Epics XL. For diagnosis of B-CLL the primary panel of MoAbs included CD19, CD20, CD5+/B-ly, CD23 together with the expression of either kappa or lambda-light chain on B-cells, and determination of CD22, CD24 and HLA D/DR.
Results: As expected, the majority of cases expressed monoclonal (-light chains (66% kappa positive related to 33% lambda positive). Median and probability of difference in paired samples is shown in the table, along with correlation coefficient:

ly gate CD19 CD20 CD22 CD23 CD24 HLA D/DR kappa lambda CD5 CD5/B
PB 90.0 87.2 81.3 17.3 67.7 74.4 87.3 15.1 2.1 92.2 77.6
BM 90.0 89.6 86.9 21.6 69.3 80.5 90.4 23.5 1.7 93.3 78.2
diff p NS NS NS NS NS NS NS <0.04 <0.03 NS NS
corr r 0.78 0.71 0.73 0.88 0.72 0.75 0.73 0.75 0.75 0.72 0.72

We confirmed that expression tended to be higher in BM compartment, but the median was higher at a statistically significant level only for light chains. The percentages of the leukemic cells and the surface antigen positivities obtained in different tumor mass-sections (PB;BM) were fully comparable in their mean expressions, medians and min/max values. Highly significant correlation (p<0.0001) was observed between individual samples with high respective correlation coefficient. Factor analysis performed on 12 variables disclosed two factors at a significant level. First factor was significantly (r>0.7) associated with CD19, 20, 23, 24, 5 and CD5/B, HLA/DR, while second factor is associated only with the expression of light chains. Only CD22 did not correlate neither with factor 1 or 2, so that its role in routine diagnostics remain to be elucidated.
Conclusions: This study has confirmed high correlation of routine MoAb expression in PB and BM, but the addition of more B-cell markers did not improve our diagnostic process. However, for research of adhesion molecules which are expected to be responsible for tumor cell re-circulation, simultaneous evaluation of PB, BM and lymph node compartments may be essential and therefore warranted.