Impact of cryopreservation on B cell chronic lymphocytic leukaemia phenotype

Background and objectives: Freezing is a practical approach for cell preser vation for retrospective studies. The aim of this work was to check the cry opreservation impact on B cell chronic lymphocytic leukaemia phenotype. Mat erial and methods: Blood samples from 15 CLL patients were analyzed freshly and after freezing at -196 degrees C, without separation, and thawing. Res ults were compared by Student's paired t-test. Results: The phenotype of fr esh CLL cells was as follows: CD19 +, CD5 +, faint CD20, CD23 +/-, weak CD2 2 and sig, CD37 +, HLA-DR +, FMC7 -. After cryopreservation, the percentage of CD5 and CD23 positive cells decreased, whereas HLA-DR positive cells in creased moderately. The CLL Matures's score was modified in 6 cases out of 15 (40%). Conclusion: Cryopreservation modifies B cell chronic lymphocytic leukaemia phenotype, by decreasing CD5 and CD23 expression. (C) 1999 Elsevi er Science B.V. All rights reserved.