Lymphocyte subset analysis on frozen whole blood

Qualification of the differential leukocyte count and immunophenotyping in cryopreserved ex vivo whole blood assay

We developed a flow cytometry-based assay, termed Differential Leukocyte Counting and Immunophenotyping in Cryopreserved Ex vivo whole blood (DLC-ICE), that allows quantification of absolute counts and frequencies of leukocyte subsets and measures expression of activation, phenotypic and functional markers. We evaluated the performance of the DLC-ICE assay by determining inter-operator variability for processing fresh whole blood (WB) from healthy donors collected at multiple clinical sites. In addition, we assessed inter-operator variability for staining of fixed cells and robustness across different anticoagulants. Accuracy was evaluated by comparing DLC-ICE measurements to real-time cell enumeration using an accredited hematology analyzer. Finally, we developed and tested the performance of a 27-colour immunophenotyping panel on cryopreserved fixed WB and compared results to matched fresh WB. Overall, we observed <20% variability in absolute counts and frequencies of granulocytes, monocytes and lymphocytes (T, B and NK cells) when fresh WB was collected in different anti-coagulant tubes, processed or stained by independent operators. Absolute cell counts measured across operators and anti-coagulants using the DLC-ICE method exhibited excellent correlation with the reference method, complete blood count (CBC) with differential, measured using a hematology analyzer (r2  > 0.9 for majority of measurements). A comparison of leukocyte immunophenotyping on fresh WB versus DLC-ICE processed blood yielded equivalent and linear results over a wide dynamic range (r2  = 0.94 over 10-104 cells/μL). These results demonstrate low variability across trained operators, high robustness, linearity and accuracy, supporting utility of the DLC-ICE assay for large cohort studies involving multiple clinical research sites.

A field method for cryopreservation of whole blood from a finger prick for later analysis with flow cytometry

OBJECTIVES

Flow cytometry is a powerful tool for investigating immune function, allowing for the quantification of leukocytes by subtype. Yet it has not been used extensively for field work due to perishable reagents and the need for immediate analysis of samples. To make flow cytometry more accessible, we devise and evaluate a field protocol for freezing capillary blood.

MATERIALS AND METHODS

We collected finger prick blood samples from 110 volunteers, age 18 to 42. Blood samples were analyzed immediately for 18 cell surface markers. Aliquots of whole blood were frozen in the vapor phase of a liquid nitrogen tank with 10% dimethyl sulfoxide in medium. Samples were analyzed on a Guava EasyCyte HT flow cytometer after 2, 4, or 14 weeks.

RESULTS

Major lymphocyte fractions in frozen samples were correlated with fresh values (T-cells: r = 0.82; Natural Killer [NK] cells: r = 0.64; CD4: r = 0.67; CD8: r = 0.82; Naïve CD4: r = 0.73, Naïve CD8: r = 0.71; B-cells: r = 0.73; all p < 0.001), and mean values were similar to those from fresh samples. However, correlations for smaller subsets of CD4 and B cells were generally poor. Some differences resulted from changes in non-specific binding for some antibody-conjugate pairs. Cryopreservation also resulted in a reduction in granulocytes more than lymphocytes.

DISCUSSION

Our results suggest that antibody/fluorochrome combinations should be validated before use on frozen samples, and that functional changes in cells may affect some cell markers. However, this simple freezing protocol utilizing finger pricks, whole blood, and a liquid nitrogen shipping tank is viable for obtaining samples for flow cytometry under field conditions.

An easy and reliable whole blood freezing method for flow cytometry immuno-phenotyping and functional analyses

BACKGROUND

Immune profiling by flow cytometry is not always possible on fresh blood samples due to time and/or transport constraints. Furthermore, the cryopreservation of peripheral blood mononuclear cells (PBMC) requires on-site specialized lab facilities, thus severely restricting the extent to which blood immune monitoring can be applied to multicenter clinical studies. These major limitations can be addressed through the development of simplified whole blood freezing methods.

METHODS

In this report, we describe an optimized easy protocol for rapid whole blood freezing with the CryoStor® CS10 solution. Using flow cytometry, we compared cellular viability and composition on cryopreserved whole blood samples to matched fresh blood, as well as fresh and frozen PBMC.

RESULTS

Though partial loss of neutrophils was observed, leucocyte viability was routinely >75% and we verified the preservation of viable T cells, NK cells, monocytes, dendritic cells, and eosinophils in frequencies similar to those observed in fresh samples. A moderate decrease in B cell frequencies was observed. Importantly, we validated the possibility to analyze major intracellular markers, such as FOXP3 and Helios in regulatory T cells. Finally, we demonstrated good functional preservation of CS10-cryopreserved cells through the analysis of intracellular cytokine production in ex vivo stimulated T cells (IFNg, IL-4, IL-17A,) and monocytes (IL-1b, IL-6, TNFa).

CONCLUSIONS

In conclusion, our protocol provides a robust method to apply reliable immune monitoring studies to cryopreserved whole blood samples, hence offering new important opportunities for the design of future multicenter clinical trials.

The Use of Dual-Cell-Tracker Dye Staining for the Identification and Characterization of Peanut-Specific T-Cell Subsets

Cell-tracker fluorescent dye labeling is widely used for investigating antigen-specific immune responses in vitro and in vivo. Here we describe a development of this technique-the use of dual-cell-tracker dye staining for the identification and characterization of the responses of different T-cell subsets to peanut proteins in vitro.

Aberrant determination of phenotypic markers in chronic lymphocytic leukemia (CLL) lymphocytes after cryopreservation

The cryopreservation of peripheral blood mononuclear cells (PBMCs) is a routine research laboratory process, enabling long-term storage of primary patient blood samples. Retrospective analysis of these samples has the potential to identify markers that may be associated with prognosis and response to treatment. To draw valid biological conclusions from this type of analysis, it is essential to ensure that any observed changes are directly related to the pathology of the disease rather than the preservation process itself. Therefore, we have investigated 15 cell surface markers that are relevant to chronic lymphocytic leukemia (CLL) on matched fresh and thawed samples to determine the effect of cryopreservation on their detection. We found that the number of CLL cells positive for the markers CD22, CD40, CD49d, CD54, CD69, and CXCR3 was decreased significantly after cryopreservation. In addition, the mean fluorescence intensity of 10 of the 15 markers changed significantly after cryopreservation. These findings demonstrate that care must be taken when interpreting this type of analysis on thawed samples.

DNA cytosine hydroxymethylation levels are distinct among non-overlapping classes of peripheral blood leukocytes

BACKGROUND

Peripheral blood leukocytes are the most commonly used surrogates to study epigenome-induced risk and epigenomic response to disease-related stress. We considered the hypothesis that the various classes of peripheral leukocytes differentially regulate the synthesis of 5-methylcytosine (5mCG) and its removal via Ten-Eleven Translocation (TET) dioxygenase catalyzed hydroxymethylation to 5-hydroxymethylcytosine (5hmCG), reflecting their responsiveness to environment. Although it is known that reductions in TET1 and/or TET2 activity lead to the over-proliferation of various leukocyte precursors in bone marrow and in development of chronic myelomonocytic leukemia and myeloproliferative neoplasms, the role of 5mCG hydroxymethylation in peripheral blood is less well studied.

RESULTS

We developed simplified protocols to rapidly and reiteratively isolate non-overlapping leukocyte populations from a single small sample of fresh or frozen whole blood. Among peripheral leukocyte types we found extreme variation in the levels of transcripts encoding proteins involved in cytosine methylation (DNMT1, 3A, 3B), the turnover of 5mC by demethylation (TET1, 2, 3), and DNA repair (GADD45A, B, G) and in the global and gene-region-specific levels of DNA 5hmCG (CD4+ T cells≫CD14+ monocytes>CD16+ neutrophils>CD19+ B cells>CD56+ NK cells>Siglec8+ eosinophils>CD8+ T cells).

CONCLUSIONS

Our data taken together suggest a potential hierarchy of responsiveness among classes of leukocytes with CD4+, CD8+ T cells and CD14+ monocytes being the most distinctly poised for a rapid methylome response to physiological stress and disease.

Adjustment of Cell-Type Composition Minimizes Systematic Bias in Blood DNA Methylation Profiles Derived by DNA Collection Protocols

Differences in DNA collection protocols may be a potential confounder in epigenome-wide association studies (EWAS) using a large number of blood specimens from multiple biobanks and/or cohorts. Here we show that pre-analytical procedures involved in DNA collection can induce systematic bias in the DNA methylation profiles of blood cells that can be adjusted by cell-type composition variables. In Experiment 1, whole blood from 16 volunteers was collected to examine the effect of a 24 h storage period at 4°C on DNA methylation profiles as measured using the Infinium HumanMethylation450 BeadChip array. Our statistical analysis showed that the P-value distribution of more than 450,000 CpG sites was similar to the theoretical distribution (in quantile-quantile plot, λ = 1.03) when comparing two control replicates, which was remarkably deviated from the theoretical distribution (λ = 1.50) when comparing control and storage conditions. We then considered cell-type composition as a possible cause of the observed bias in DNA methylation profiles and found that the bias associated with the cold storage condition was largely decreased (λ_adjusted = 1.14) by taking into account a cell-type composition variable. As such, we compared four respective sample collection protocols used in large-scale Japanese biobanks or cohorts as well as two control replicates. Systematic biases in DNA methylation profiles were observed between control and three of four protocols without adjustment of cell-type composition (λ = 1.12–1.45) and no remarkable biases were seen after adjusting for cell-type composition in all four protocols (λ_adjusted = 1.00–1.17). These results revealed important implications for comparing DNA methylation profiles between blood specimens from different sources and may lead to discovery of disease-associated DNA methylation markers and the development of DNA methylation profile-based predictive risk models.

Stable phenotype of B-cell subsets following cryopreservation and thawing of normal human lymphocytes stored in a tissue biobank

BACKGROUND

Cryopreservation is an acknowledged procedure to store vital cells for future biomarker analyses. Few studies, however, have analyzed the impact of the cryopreservation on phenotyping.

METHODS

We have performed a controlled comparison of cryopreserved and fresh cellular aliquots prepared from individual healthy donors. We studied circulating B-cell subset membrane markers and global gene expression, respectively by multiparametric flow cytometry and microarray data. Extensive statistical analysis of the generated data tested the concept that "overall, there are no phenotypic differences between cryopreserved and fresh B-cell subsets." Subsequently, we performed an uncontrolled comparison of tonsil tissue samples.

RESULTS

By multiparametric flow analysis, we documented no significant changes following cryopreservation of subset frequencies or membrane intensity for the differentiation markers CD19, CD20, CD22, CD27, CD38, CD45, and CD200. By gene expression profiling following cryopreservation, across all samples, only 16 out of 18708 genes were significantly up or down regulated, including FOSB, KLF4, RBP7, ANXA1 or CLC, DEFA3, respectively. Implementation of cryopreserved tissue in our research program allowed us to present a performance analysis, by comparing cryopreserved and fresh tonsil tissue. As expected, phenotypic differences were identified, but to an extent that did not affect the performance of the cryopreserved tissue to generate specific B-cell subset associated gene signatures and assign subset phenotypes to independent tissue samples.

CONCLUSIONS

We have confirmed our working concept and illustrated the usefulness of vital cryopreserved cell suspensions for phenotypic studies of the normal B-cell hierarchy; however, storage procedures need to be delineated by tissue-specific comparative analysis.

Optimization of a whole blood phenotyping assay for enumeration of peripheral blood leukocyte populations in multicenter clinical trials

Vaccination with viral vectors or adjuvants can induce early changes in circulating peripheral blood leukocytes that are predictive of a protective immune response. In this study, we define an 11-color whole blood antibody staining Trucount Panel (TP1) to enumerate and phenotype the major leukocyte populations in a human vaccine experimental medicine trial setting. TP1 can be prepared up to 8weeks prior to use, enabling bulk preparation at a central laboratory and distribution to clinical sites. Cells in whole blood must be stained within 4h of draw to accurately detect the major cell populations. Staining of cells with TP1 followed by storage and shipping at -80°C to a central laboratory has little to no effect on the cell concentrations observed. We also present data from an HIV vaccine multicenter clinical trial obtained using the optimized TP1 assay protocol and show that the data produced accurately correlates with complete blood count (CBC) data. Taken together, these data indicate the optimized TP1 panel assay can be used in a multicenter clinical trial setting to increase our understanding of systemic responses to vaccination or disease.

Flow cytometric immunphenotyping of epithelial cancer cells in effusions—Technical considerations and pitfalls

BACKGROUND

Data regarding the role of flow cytometry (FCM) in the characterization of malignant effusions are limited to date. In the present study, we optimized the conditions for FCM immunphenotyping of effusions using a four-color analysis and investigated aspects related to the advantages and limitations of this method in this setting.

METHODS

FCM analysis optimization for the study of epithelial cells was undertaken using five carcinoma cell lines, and subsequently applied to malignant pleural and peritoneal effusions using antibodies against epithelial and mesothelial markers (Ber-EP4 and EMA), CD138, and integrin subunits. FCM of frozen versus fresh specimens and the performance of FCM compared to immunhistochemistry were evaluated.

RESULTS

FCM optimization was achieved and applied to clinical specimens, with resulting detection of epithelial markers and adhesion molecules on cancer cells. Frozen clinical specimens and cell lines showed reduced CD138 expression compared to fresh specimens, with conservation of the remaining epitopes. FCM generally showed comparable performance to immunhistochemistry.

CONCLUSIONS

FCM is an effective method for characterization of cancer cells in clinical effusion specimens in both the diagnostic and research setting, and is comparable to immunhistochemistry in terms of sensitivity and specificity, with the additional advantage of providing quantitative data. The majority of epitopes are conserved in frozen cells, but a minority may be lost, suggesting that the thorough testing of each antibody in both conditions is mandatory.

High-potentiality preliminary selection criteria and transformation time-dependent factors analysis for establishing Epstein-Barr virus transformed human lymphoblastoid cell lines

Infection of freshly isolated and cryopreserved lymphocytes with Epstein-Barr virus (EBV) leads to the establishment of human B lymphoblastoid cell lines (LCLs). Techniques for optimal infection of the lymphocytes are vital for the establishment of a human biobank. The present study found that more than half (58-86%) of such established LCLs had transport times of less than 48 h, cell densities exceeding 10(6) cells/ml and cell viabilities greater than 90%. After EBV infection, 3306 freshly isolated lymphocytes required 30.0 +/- 0.1 days to become LCLs. Conversely, 1210 cryopreserved lymphocytes required 36.2 +/- 0.4 days. Cell density and viability of the culture affected transformation time in freshly isolated lymphocytes. On the other hand, blood transport time, cryopreservation time and initial cell viability were major factors in cryopreserved specimens. These results contribute to general information concerning the establishment of a human biobank for EBV infected cells.

Prevalence of HIV in the US Household Population

To examine trends in HIV prevalence in the US household population, serum or urine samples from 2 National Health and Nutrition Examinations Surveys (NHANES) (1988-1994 and 1999-2002), were tested for HIV antibody. In the 1999 to 2002 survey, data on risk behaviors, CD4 T lymphocytes, and antiretroviral therapy (ART) were also available. In the 1988 to 1994 survey, there were 59 positive individuals of 11,203 tested. In NHANES 1999 to 2002, there were 32 positive individuals of 5926 tested. The prevalence of HIV infection among those aged 18 to 39 years in NHANES 1988 to 1994 was 0.38% (95% confidence interval [CI]: 0.22-0.68) as compared with 0.37% (95% CI: 0.17 to 0.80) in 1999 to 2002. Prevalence did not change significantly between surveys in any race and/or ethnic or gender group among 18- to 39-year-old participants. HIV prevalence was 3.58% (95% CI: 1.88 to 6.71) among non-Hispanic blacks in the 40- to 49-year-old age group in 1999 to 2002, but the age range available in NHANES 1988 to 1994 was 18 to 59 years and does not allow direct comparison of prevalence. Cocaine use and the presence of herpes simplex virus-2 antibody were the only significant risk factors for HIV infection for non-Hispanic blacks. Fifty-eight percent of infected individuals not reporting ART had CD4 T-lymphocyte counts < 200 cells/mm3 compared with 18.2% on therapy and 12.5% of participants newly informed of their HIV status.

Flow cytometric analysis of macaque whole blood for antigen-specific intracellular cytokine production by T lymphocytes

We report here the standardized conditions for stimulation of macaque whole blood samples with various protein or peptide antigens, and production of significant intracellular levels of interferon gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) in CD4+ as well as CD8+ T lymphocytes. We observed significantly higher levels of TNF-alpha compared with IFN-gamma in both CD4+ and CD8+ T lymphocytes from all the macaque whole blood samples stimulated with staphylococcal enterotoxin B (SEB) as an antigen. Similarly, when whole blood samples from rhesus macaques immunized with an HIV envelope peptide cocktail vaccine were stimulated with either the peptide cocktail or recombinant gp160, we observed production of significant levels of TNF-alpha by both CD4+ and CD8+ T lymphocytes. These results strongly support the utility of the whole blood cytokine flow cytometry methodology for determining antigen-specific immune responses of macaques in vaccine studies.

Genetic diversity and HIV-1 incidence estimation among cocaine users in São Paulo, Brazil

We describe HIV-1 incidence and the prevalence of genetic subtypes among cocaine users in São Paulo, Brazil. A cross-sectional HIV-1 survey was carried out among 839 current cocaine users attending seven drug treatment units in the São Paulo metropolitan area from 1997 to 1998. HIV-1 subtyping was performed among 41 positive individuals using the heteroduplex mobility assay and DNA sequencing. Participants were mainly male (95.7%) with a history of previous imprisonment (54%), and the mean age was 26.9 years (SD = 7.2). The majority (64.4%) were current crack cocaine users, and 82.1% of the total participants were noninjectors. HIV-1 seroprevalence was 4.9% (95% confidence interval [CI], 3.6%-6.6%), and the incidence (estimated by the sensitive/less-sensitive immunoassay testing strategy) was 0.71% per year (95% CI, 0.07-3.03). HIV-1 subtype B was predominant (90.3%), followed by subtype F. There was no statistically significant association between HIV-1 subtype and specific route of drug administration. Our incidence data show evidence of recent HIV-1 transmission among cocaine users, mainly among noninjectors. Detection of recently infected HIV-1 cases linked to genetic diversity analysis may provide baseline information for public health interventions in this sentinel group.

Donor WBCs can persist and transiently mediate immunologic function in a murine transfusion model: effects of irradiation, storage, and histocompatibility

BACKGROUND

Donor WBCs are responsible for numerous transfusion complications, but little is known concerning the natural history of their clearance following transfusion or of their function in the recipient's circulation. A murine transfusion model was developed to investigate the effects of blood component characteristics and histocompatibility on donor WBC survival kinetics and function.

STUDY DESIGN AND METHODS

To investigate the effects of storage and irradiation, fresh whole blood and blood stored for 1, 2, and 6 weeks at 4 degrees C, all from male C57b (H2K(b)) mice, was transfused to female Balb/c (H2K(d)) mice. To study the effect of histocompatibility, blood was also transfused from C57b mice to Balb/c, FVB, C3H, and SW (outbred) mice. To investigate the xenogeneic setting, blood from humans, rats, and rabbits was transfused to Balb/c mice. Samples were collected weekly after transfusion, and the donor WBCs were analyzed, targeting the Y-chromosome with quantitative PCR. To investigate donor WBC function, dinitrochlorobenzene (DNCB) sensitivity was induced in donor and recipient mice, and the transfusion recipients were observed for hypersensitivity to DNCB.

RESULTS

Donor WBCs had reduced in vivo survival equivalent to their period of storage ex vivo at 4 degrees C. Irradiation of donor blood produced no observable difference in donor WBC survival. Allogeneic male donor WBCs persisted (100-<1 cell/microL) in female Balb/c recipient mice blood over 6 weeks. Donor WBC survival kinetics displayed an early MHC-dependent phase, which was followed by a more rapid phase that was not influenced by donor-recipient MHC differences. All donor WBCs were cleared within 24 to 48 hours. DNCB sensitivity was passed through transfusion, where it was transiently expressed in naive recipients.

CONCLUSION

The clearance of donor WBCs in the murine transfusion model is much slower than that in humans. Allogeneic donor WBC clearance may be biphasic, involving MHC-dependent as well as MHC-independent mechanisms. DNCB sensitivity can be transferred transiently to a naive recipient.

Qualitative and quantitative PCR measures of cytomegalovirus in patients with advanced HIV infection who require transfusions

The Viral Activation Transfusion Study (VATS) was a randomized trial that compared leukocyte-reduced transfusions with unfiltered red blood cell transfusions in HIV and cytomegalovirus (CMV) antibody-positive patients with anemia who were undergoing their first blood transfusion. The relations of the baseline qualitative and quantitative polymerase chain reaction (PCR) measures of plasma CMV viremia, HIV RNA, CD4(+) cell counts, and quality of life in these study subjects were examined. The 511 study subjects had a median CD4(+) cell count equal to 15 cells/mm3, and 110 (21.5%) had CMV viremia by qualitative assay. In multivariate models, frequency of positive qualitative CMV increased with decreasing CD4(+) cell counts (p =.04 trend), higher HIV RNA (p <.001), and a history of CMV disease (p <.001). Quantitative CMV PCR were performed on the 110 qualitative assay-positive study subjects. Median CMV viral load was 1780 copies/ml. In multivariate regression models, lower CD4(+) cell count (p =.03), and a history of CMV disease (p <.001) correlated with the level of CMV load. HIV RNA load and CMV load were not correlated. A lower Karnofsky score was associated with both the presence and quantity of CMV DNA.

Preparation of cells from blood

Peripheral blood is a bountiful source of numerous cell types that are easily analyzed by flow cytometry for a variety of properties. The monodisperse nature of blood makes preparation of these cells relatively easy if the coagulation cascade is inhibited. For some studies the presence of serum can be a confounding factor, although this is often overcome by merely pelleting the cells from the serum and washing the remaining cells several times. Blood, particularly from humans and primates, should be considered highly infectious whether or not from a healthy donor. Therefore universal precautions should be followed at all times. Techniques and route of collection may have a profound influence on the condition and nature of the blood being obtained. Performing venipuncture with an extremely small gauge needle may disrupt cells and prevent satisfactory analysis. Venous blood and arterial blood may yield differing data. Even blood collection at different times of day may yield diurnal variations in some assays. The demands of each cell type and of each assay dictate specific preparation, fixation, storage, and staining protocols. However, the overall goal for preparation of cells from blood, for all of the assays, remains the same--collect and prepare the cells in such a manner that they accurately represent the in vivo state.

'Modeling' relationships among HIV-1 replication, immune activation and CD4+ T-cell losses using adjusted correlative analyses

OBJECTIVE

To model the relationships among HIV-1 replication, immune activation and CD4+ T-cell losses in HIV-1 infection.

METHODS

Cross-sectional analysis of baseline data from the Viral Activation by Transfusion Study. Comparisons of unadjusted and adjusted correlative analyses to establish models for mechanisms of cell loss in AIDS.

RESULTS

Using these analyses, significant correlations were found among plasma levels of tumor necrosis factor alpha (TNFalpha) and its type two receptor (TNFrII), interleukin-6 (IL-6), beta2-microglobulin, expression of CD38 and HLA-DR on CD8+ T lymphocytes and plasma levels of HIV-1 RNA. When correlations among these indices were adjusted for possible intermediary correlations, the relationship between HIV-1 RNA levels and all plasma markers of immune activation could be accounted for by the correlation between plasma HIV-1 RNA and plasma TNFrII levels. In addition, the negative correlations that both HIV-1 RNA levels and TNFrII levels had with CD4+ T-cell counts were partially accounted for by the correlations of HIV-1 RNA and TNFrII with CD38 expression on CD8+ T cells. In persons with advanced disease (CD4+ T cells < 50 x 10(6)/l) IL-6 levels were inversely correlated with CD4+ T-cell counts.

CONCLUSIONS

This analysis is consistent with a model wherein HIV-1 replication induces TNFalpha expression that induces multiple other indices of immune activation. In this model, HIV-1 replication and TNFalpha expression induce CD4+ T-cell losses at least in part through mechanisms reflected in heightened CD38 expression.

Impact of cryopreservation on B cell chronic lymphocytic leukaemia phenotype

BACKGROUND AND OBJECTIVES

Freezing is a practical approach for cell preservation for retrospective studies. The aim of this work was to check the cryopreservation impact on B cell chronic lymphocytic leukaemia phenotype.

MATERIAL AND METHODS

Blood samples from 15 CLL patients were analyzed freshly and after freezing at -196 degrees C, without separation, and thawing. Results were compared by Student's paired t-test.

RESULTS

The phenotype of fresh CLL cells was as follows: CD19+, CD5+, faint CD20, CD23+/-, weak CD22 and sIg, CD37+, HLA-DR+, FMC7-. After cryopreservation, the percentage of CD5 and CD23 positive cells decreased, whereas HLA-DR positive cells increased moderately. The CLL Matutes'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.