Expression of CD44 (HCAM) in small lymphocytic and mantle cell lymphoma

Symmetric palatal swelling as the first clinical manifestation of a mantle cell non-Hodgkin's lymphoma: A case report and review of literature

The mantle cell lymphoma (MCL) is a rare (3.7%) low-grade non-Hodgkin lymphoma originating from the B-cell precursor-subpopulation. The clinical appearance in the oral cavity is rare. Since 1980, nine cases have been reported. A 41-year-old patient showed a MCL presenting with a symmetric, painless palatal swelling without any other clinical symptoms. Histological sections revealed malignant monotonous lymphoid cells (CD20+, CD43+, Ki67+) and the typical cyclinD1 over-expression by the chromosomal translocation t(11;14)(q13;q32). The proliferating cells weekly expressed CD5, kappa-and lambda-light chains and no EMA, CD10, bcl-6, CD30, and CD23. The patient was treated according to the European MCL younger study, and the MCL is regressive. The high incidence of dento-alveolar abscesses, inflammations, or benign tumor-formations leads to associate any maxillary or palatal swelling with this clinical condition. Considering the serious consequences of a missed therapy a histological examination of any untypical “swelling” is demanded.

The microenvironment in mantle cell lymphoma: cellular and molecular pathways and emerging targeted therapies

There is growing evidence suggesting that cross talk between mantle cell lymphoma (MCL) cells and stromal cells in tissue microenvironments, such as the bone marrow and secondary lymphoid organs, causes disease progression by promoting lymphoma cell survival, growth, and drug resistance. Conceivably, while conventional treatment eliminates the bulk of MCL cells, residual lymphoma cells may lurk in protective tissue niches, where they receive signals from accessory cells that promote survival and drug-resistance, thereby paving the way for residual disease and relapses. Based on this concept, the lymphoma microenvironment has become a growing area of current research, and initial clinical trials targeting cross talk between MCL cells and their microenvironment are showing promising early results. In this review, we summarize key cellular and molecular interactions between MCL cells and their microenvironment, and update new clinical developments in this area.

Epigenetic regulation of CD44 in Hodgkin and non-Hodgkin lymphoma

Background

Epigenetic inactivation of tumor suppressor genes (TSG) by promoter CpG island hypermethylation is a hallmark of cancer. To assay its extent in human lymphoma, methylation of 24 TSG was analyzed in lymphoma-derived cell lines as well as in patient samples.

Methods

We screened for TSG methylation using methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) in 40 lymphoma-derived cell lines representing anaplastic large cell lymphoma, Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), Hodgkin lymphoma and mantle cell lymphoma (MCL) as well as in 50 primary lymphoma samples. The methylation status of differentially methylated CD44 was verified by methylation-specific PCR and bisulfite sequencing. Gene expression of CD44 and its reactivation by DNA demethylation was determined by quantitative real-time PCR and on the protein level by flow cytometry. Induction of apoptosis by anti-CD44 antibody was analyzed by annexin-V/PI staining and flow cytometry.

Results

On average 8 ± 2.8 of 24 TSG were methylated per lymphoma cell line and 2.4 ± 2 of 24 TSG in primary lymphomas, whereas 0/24 TSG were methylated in tonsils and blood mononuclear cells from healthy donors. Notably, we identified that CD44 was hypermethylated and transcriptionally silenced in all BL and most FL and DLBCL cell lines, but was usually unmethylated and expressed in MCL cell lines. Concordant results were obtained from primary lymphoma material: CD44 was not methylated in MCL patients (0/11) whereas CD44 was frequently hypermethylated in BL patients (18/29). In cell lines with CD44 hypermethylation, expression was re-inducible at mRNA and protein levels by treatment with the DNA demethylating agent 5-Aza-2'-deoxycytidine, confirming epigenetic regulation of CD44. CD44 ligation assays with a monoclonal anti-CD44 antibody showed that CD44 can mediate apoptosis in CD44⁺ lymphoma cells. CD44 hypermethylated, CD44^- lymphoma cell lines were consistently resistant towards anti-CD44 induced apoptosis.

Conclusion

Our data show that CD44 is epigenetically regulated in lymphoma and undergoes de novo methylation in distinct lymphoma subtypes like BL. Thus CD44 may be a promising new epigenetic marker for diagnosis and a potential therapeutic target for the treatment of specific lymphoma subtypes.

Aberrant immunophenotypes of mantle cell lymphomas

Mantle cell lymphomas (MCL) are characterized by cytomorphological criteria, a distinct immunophenotype and a characteristic chromosomal aberration (t(11;14)). In morphological variants of MCL the immunohistochemical constellation with CD5-positivity and CD23-negativity is a helpful and decisive diagnostic aid to differentiate MCL from other B-cell-lymphomas, e.g. lymphocytic lymphomas (B-CLL). In this study the morphological, immunophenotypical, and genetical features of 50 MCL were analysed. Five cases revealed an aberrant immunophenotype with lacking expression of CD5 (n = 3) and positive reactivity to CD23 (n = 2) while cyclin D1 expression could be demonstrated in all 5 cases. These constellations show that there is, besides morphological subgroups, a small group of MCL with aberrant immunophenotypes, which has to be taken into account in the differential diagnosis to lymphocytic lymphoma and other lymphomas.

CD5- mantle cell lymphoma

Mantle cell lymphoma (MCL) typically expresses B-cell antigens and CD5 and overexpresses bcl-1 protein. However, unusual cases of bcl-1+ and CD5-MCL have been observed, posing a practical challenge for correct diagnosis and management. We identified 25 cases (48 samples) of bcl-1+ and CD5- lymphoma. CD5 expression was assessed by flow cytometric analysis alone (1 case), immunohistochemical analysis alone (17 cases), or dual flow cytometric/immunohistochemical methods (7 cases). The morphologic features were consistent with MCL with centrocytic cytomorphology in 20 cases and blastic variant in 5 cases. The t(11;14) was confirmed in 8 of 11 cases by fluorescence in situ hybridization of paraffin-embedded tissue. Cytogenetic analysis revealed the t(11;14) within a complex karyotype in 2 additional cases. These data show that MCL may lack CD5 expression. Evaluation of bcl-1 expression by immunohistochemical analysis or molecular genetics may be indicated if MCL is suspected clinically or morphologically despite a lack of CD5 expression.

Reference values for peripheral blood B-lymphocyte subpopulations: a basis for multiparametric immunophenotyping of abnormal lymphocytes

BACKGROUND AND OBJECTIVES

Immunophenotyping has become a useful tool for the differential diagnosis of chronic B-cell lymphoproliferative disorders. The aim of this work was to determine reference values of normal B-cell subpopulations.

MATERIAL AND METHODS

Blood samples from 38 healthy volunteers were analyzed by multidimensional flow cytometry, using a panel of directly conjugated antibodies. Results were expressed as percent of positive B cells and as median fluorescence intensity, an indirect assessment of the expression level.

RESULTS

CD20, CD22, CD24, CD40, CD79a, CD79b, FMC7, CD11a, CD18, CD44 were positive in the whole B cell population, whereas CD10, CD86, CD103, CD154 and FasL were almost absent from the B-lymphocyte population. 75% were IgD positive. The kappa/lambda ratio was 1.5. CD5, CD23, CD25, CD38, CD43, CD54, CD62L, CD80 and CD95 were positive in different B-cell subpopulations. The utility of all these markers in the differential diagnosis of chronic B-cell lymphoproliferative disorders is discussed.

CONCLUSION

In order to interpret a pathological immunophenotype, it is necessary to refer to quantitative and qualitative values of normal B-cell subpopulations.

Mantle-cell lymphoma

During the past decade, mantle-cell lymphoma has been established as a new disease entity. The normal counterparts of the cells forming this malignant lymphoma are found in the mantle zone of the lymph node, a thin layer surrounding the germinal follicles. These cells have small to medium-sized nuclei, are commonly indented or cleaved, and stain positively with CD5, CD20, cyclin D1, and FMC7 antibodies. Because of its morphological appearance and a resemblance to other low-grade lymphomas, many of which grow slowly, this lymphoma was initially thought to be an indolent tumour, but its natural course was not thoroughly investigated until the 1990s, when the BCL1 oncogene was identified as a marker for this disease. Mantle-cell lymphoma is a discrete entity, unrelated to small lymphocytic or small-cleaved-cell lymphomas.

Usefulness of CD79b expression in the diagnosis of B-cell chronic lymphoproliferative disorders

We evaluated anti-CD79b for its usefulness in the diagnosis of B-cell chronic lymphoproliferative disorders (BCLPDs), particularly chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL). We analyzed 100 BCLPDs for CD5, CD19, CD20, CD23, CD79b, and surface immunoglobulin light chain (sIg) expression by 4-color flow cytometry. CD20, CD79b, and sIg expression were quantified. Correlational analysis and univariable and multivariable logistic regression models were used to determine the best combination of antigens for the immunophenotypic classification of CLL vs other BCLPDs. Positive and statistically significant Spearman pairwise correlations between CD20, CD79b, and sIg fluorescence intensity were demonstrated. In the simplest models in which a single variable was considered, cutoff points were chosen that gave misclassification rates for CLL of 16% for CD79b, 19% for sIg, and 18% for CD20. Low-intensity CD79b, CD20, and sIg are associated highly with CLL. A panel containing CD5, CD19, CD23, and sIg allowed correct classification of most cases. Addition of CD20 or CD79b improved diagnostic accuracy; CD79b was slightly better than CD20. CD79b seems to be a useful addition to a standard flow cytometry panel for the evaluation of BCLPDs.

Classification of small B-cell lymphoid neoplasms using a paraffin section immunohistochemical panel

Immunophenotypic analysis is critical in categorizing small B-cell neoplasms; however, many recommended antibody panels have required fresh or frozen tissue. Many paraffin-reactive antibodies are now available but have been studied mostly in isolation. Therefore, the utility of a panel of paraffin-reactive antibodies in differentiating small B-cell neoplasms was investigated. Paraffin-embedded sections of small lymphocytic lymphoma/B-chronic lymphocytic leukemia (SLL/B-CLL; 12), mantle cell (MCL; 15), follicular (FL; 11), and marginal zone B-cell (MZL; eight) lymphomas were stained with CD20/L26, CD3, CD43/DF-T1 or Leu22, CD5/4C7, CD23/BU38, cyclin D1/H295, and CD10/56C6 antibodies. For select antibodies, results were compared to flow cytometric data (FC). Formalin and B5 fixation were also compared. Seven of 11 SLL/B-CLL were CD43+ CD5+ CD23+ cyclin D1- CD10-; seven of 11 MCL were CD43+ CD5+ CD23- cyclin D1+ CD10-; nine of 10 FL were CD43- CD5- CD23- cyclin D1- CD10+; and five of six MZL were CD43+ CD5- CD23- cyclin D1- CD10-. CD5, CD23, and CD10 stains showed sensitivities of 81, 88, and 100%, respectively, compared to FC. With B5 fixation, cyclin D1 was more often negative and CD5 more often equivocal. A panel of paraffin-reactive antibodies aids in classification of small B-cell neoplasms, although a small number of cases have indeterminate phenotypes and MZL have no defining features. CD5 separates most SLL/B-CLL and MCL from FL and MZL. CD23 separates SLL/B-CLL from most MCL, but cyclin D1 is most important for identifying MCL. CD10 positivity distinguishes most FL from other small B-cell lymphoid neoplasms.