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Hematol J. 2001;2(5):300-6.

Variability in B-cell antigen expression: implications for the treatment of B-cell lymphomas and leukemias with monoclonal antibodies.

Author information

1
Department of Oncology (Radiumhemmet), Cancer Center Karolinska, Karolinska Hospital, Stockholm, Sweden.

Abstract

OBJECTIVES:

Antigen expression intensity is becoming important for decision-making in relation to monoclonal antibody therapy. By quantifying CD20, CD22 and CD52 expression on chronic lymphocytic leukemia and normal (control) B cells, over time. The effect of Interleukin-4 therapy on CD20 antigen intensity on B-CLL cells in vivo was also determined.

METHODS:

Lymphocytes were purified at weeks 0, 4 and 8 from five B-CLL patients, five healthy volunteers and seven B-CLL patients receiving IL-4 therapy. The number of antigen receptor sites was calculated in molecules of equivalent soluble fluorochrome using flow cytometry.

RESULTS:

The mean number of CD20 receptors at baseline was significantly lower on B-CLL cells compared to normal B cells (8160 vs 87 046; P<0.0001). Similar results were obtained for CD22 (8630 vs 27 647; P<0.01), but not for CD52 (371 303 vs 409 484; P = 0.54). When soluble fluorochrome values at weeks 4 and 8 were analysed as change in per cent from baseline (delta%), there was <10 delta% variability in CD20 expression on control B cells, but considerable variability (22.5-67.5 delta%) on B-CLL cells. Expression of CD22 in CLL and control B cells varied by <15 delta%. CD52 on CLL B cells showed slightly greater variability (+/-35 delta%) than that of CD22 (+/-15delta%), but less than that of CD20. IL-4 therapy did not consistently increase the CD20 expression on B-CLL cells in vivo.

CONCLUSION:

Our data confirm differences in intensity between different target antigens on B-CLL cells, and draws attention to the fact that a substantial variability may occur over time, which may influence clinical decision-making. Caution must be taken when interpreting in vitro results on cytokine-mediated receptor intensity up-regulation.

PMID:
11920265
DOI:
10.1038/sj/thj/6200119
[Indexed for MEDLINE]

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