A single tube, four-color flow cytometry assay for evaluation of ZAP-70 and CD38 expression in chronic lymphocytic leukemia

Clonality assessment of cutaneous B-cell lymphoid proliferations: a comparison of flow cytometry immunophenotyping, molecular studies, and immunohistochemistry/in situ hybridization and review of the literature

Cutaneous lymphoid infiltrates are diagnostically challenging. Although ancillary techniques to assess clonality can help distinguish between reactive lymphoid hyperplasia and lymphoma, one of the most widely used techniques in hematopathology, flow cytometry immunophenotyping (FCI), has not been routinely applied to skin specimens. We performed FCI on 73 skin specimens from 67 patients clinically suspected of having a cutaneous B-cell lymphoma (CBCL) and compared the results with those obtained from immunoglobulin heavy chain (IGH) gene molecular studies (58 cases, primarily by polymerase chain reaction) and either immunohistochemistry (IHC) or in situ hybridization to evaluate for light chain restriction (22 and 2 cases, respectively). Sufficient quantity of CD45 (leukocyte common antigen)-positive cells and staining quality were achieved in 88% of cases by FCI, and clonality was detected in 68% of CBCLs versus molecular studies showing sufficient DNA quality in 74% and only 39% clonality detection, and interpretable/contributory IHC results in 84% of cases with 55% clonality detection. Clonality was documented more frequently in secondary rather than primary CBCLs by all 3 techniques. Therefore, FCI is feasible and appears to be more reliable than molecular studies or IHC/in situ hybridization for detecting clonality in CBCLs and can provide additional prognostically and therapeutically relevant information. The exception is cases with plasmacytic differentiation such as marginal zone lymphoma for which IHC might be a superior tool. We have also shown that a large subset of primary cutaneous follicle center lymphomas express CD10 and/or BCL2 by FCI. Recent advances in FCI beg the question of applicability to cutaneous T-cell and NK-cell lymphomas.

Perifosine treatment in chronic lymphocytic leukemia: results of a phase II clinical trial and in vitro studies

Abstract Because of the importance of the phosphoinositide 3-kinase (PI3K)/AKT pathway in chronic lymphocytic leukemia (CLL), we evaluated in vitro cytotoxicity induced by perifosine, an AKT inhibitor, in CLL lymphocytes and found that the mean 50% effective dose (ED50) was 313 nM. We then performed a phase II trial of perifosine in patients with relapsed/refractory CLL to assess response, outcomes, toxicity and ex vivo correlative measures. After 3 months of treatment, six of eight patients showed stable disease, one achieved a partial response and one had progressive disease. Median event-free survival and overall survival in all patients treated were 3.9 and 9.7 months. Adverse events included hematologic, infectious/fever, pain, gastrointestinal and constitutional toxicities. Unexpectedly, AKT phosphorylation in CLL lymphocytes from treated patients was not correlated with response. Additionally, perifosine did not inhibit AKT phosphorylation in cultured CLL lymphocytes. Perifosine is cytotoxic to CLL cells in vitro, and largely induces stabilized disease in vivo, with an AKT-independent mechanism.

Surface profiles for subclassification of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) has a variable clinical course. Some patients have stable disease while others progress and require treatment. Levels of several cluster of differentiation (CD) antigens are known to correlate with prognosis and may be used to stratify patients according to risk. In this review, we summarize current information on surface CD antigens found on CLL, their pathological significance and their detection using CD antibody microarrays. The use of extensive immunophenotypic patterns or surface profiles as disease signatures for CLL subclassification, prognosis and patient management is discussed with a focus on triaging patients with CLL with progressive disease.

Improved flow cytometric detection of ZAP-70 in chronic lymphocytic leukemia using experimentally optimized isotypic control antibodies

INTRODUCTION

Expression of ZAP-70 by chronic lymphocytic leukemia (CLL) is associated with more aggressive disease and can help differentiate CLL using mutated immunoglobulin heavy chain variable genes (VH) from cases expressing unmutated VH genes. However, flow cytometric detection of ZAP-70 in CLL shows considerable variability and may be of questionable significance because most laboratories cannot correlate their results to clinical outcome or VH mutational data.

METHODS

Seventy cases of CLL were evaluated for ZAP-70 using a previously optimized staining procedure and two different methods to eliminate nonspecific background staining. One method, not previously reported, used isotypic control antibodies, where the concentrations were adjusted/optimized so that normal B-cells stained negatively for ZAP-70. The other used ZAP-70 stained peripheral blood B-cells from normal donors. The percentages of ZAP-70 stained CLL cells above the two thresholds were compared.

RESULTS

Concentrations of isotypic control antibodies had to be increased from manufacture's recommendations to insure normal B-cells were ZAP-70 negative. ZAP-70 levels among the CLL cases formed a bimodal distribution using the optimized isotypic control threshold, with 30 having low values (0-32% positive) and 40 high values (60-99% positive). In contrast, a continuous distribution was obtained with the ZAP-70 stained B-cell threshold. VH mutational status strongly correlated with the optimized control values as 29/30 low ZAP-70 cases had mutated VH genes and 37/40 high ZAP-70 cases used unmutated VH genes.

CONCLUSIONS

Use of an optimized isotypic control threshold could increase the reliability of flow based ZAP-70 detection and correlates well with VH mutational status.