Showing papers by "Constance M. Yuan published in 2009"

Variable CD52 expression in mature T cell and NK cell malignancies: implications for alemtuzumab therapy.

Abstract: The anti-CD52 antibody alemtuzumab has been explored as a novel targeted therapy in T cell malignancies. To assess the suitability of alemtuzumab therapy, we carried out a comprehensive study of CD52 expression using flow cytometry (FC) in 78 untreated patients diagnosed with mature T/natural killer (NK) cell neoplasms, including 34 adult T cell leukaemia/lymphomas (ATLL), two anaplastic large cell lymphomas (ALCL), three angioimmunoblastic T cell lymphomas (AITL), 16 cutaneous T cell lymphomas (CTCL), four extra-nodal T/NK cell lymphomas (ENT/NKCL), four hepatosplenic T cell lymphomas (HSTCL), 13 peripheral T cell lymphomas, not otherwise specified (PTCL-NOS) and two T-prolymphocytic leukaemia (T-PLL). The level of CD52 expression was quantified using QuantiBRITE standard beads. The level of CD52 expression varied widely within each diagnostic category. All AITL, HSTCL and T-PLL cases were CD52-positive and the frequency of CD52 expression was high in PTCL-NOS (92.3%), ATLL (94.1%) and CTCL (87.5%), implying a rational role for alemtuzumab in the treatment of these diseases; however, CD52 expression was low in ALCL (50%) and ENT/NKCL (25%). FC testing for cell surface expression of CD52 is indicated in patients with T/NK cell malignancies being considered for alemtuzumab therapy. Further studies are necessary to determine if the level of CD52 expression correlates with response to therapy.

Novel CD19 expression in a peripheral T cell lymphoma: A flow cytometry case report with morphologic correlation.

Abstract: Background Peripheral T-cell lymphomas are uncommon lymphomas that show T-cell antigenic loss and clonal T-cell receptor (TCR) gene rearrangement. Rare cases of T-cell lymphomas with aberrant expression of CD20 have been described. However, CD19 coexpression in a mature T-cell neoplasm has not been reported. Methods Histology, immunohistochemistry (IHC), and PCR for TCR gene rearrangement were performed on an excised lymph node specimen and a subsequent fine needle aspiration (FNA) of an additional lymph node. Flow cytometry (FC) was performed on FNA and peripheral blood specimen. Results The lymph node's architecture was effaced by a diffuse atypical lymphoid proliferation that, by IHC, was positive for CD3, CD2, and CD43 and negative for CD4, CD5, CD8, TdT, CD1a, and B-cell-associated antigens PAX-5, CD20, and CD79a. A clonal TCR gene rearrangement was detected. FC was performed on a subsequent FNA, and peripheral blood specimen demonstrated an aberrant T-cell population with expression of CD2, CD3, CD27, TCR α/β, CD52, CD38, CD45, and CD26 (partial expression) and negative for CD4, CD5, CD7, CD8, CD10, CD30, and CD56. The aberrant T-cell population also expressed bright CD19. Conclusions Using FC, we describe the first case of peripheral T-cell lymphoma with aberrant coexpression of CD19. Published 2008 Wiley-Liss, Inc.

Visual inspection versus quantitative flow cytometry to detect aberrant CD2 expression in malignant T cells.

Abstract: Background: Abnormal levels of T-cell antigen expression occur in T-cell neoplasia. We examined CD2 expression in malignant and normal T cells to determine if the level of CD2 expression differed significantly and if quantitation assisted in detecting this difference. Method: Flow cytometric immunophenotypic (FCI) evaluation was performed on specimens from 36 patients with mature T-cell neoplasia. Abnormal T cells were identified based upon the abnormal FCI and morphology. Levels of CD2 expression were quantitated using 1:1 PE conjugates of anti-CD2 and QuantiBRITE bead standards to calculate the antibodies bound per cell (ABC). The efficacy of ABC measurement versus simple examination of dots plots was compared. Results: Abnormal levels of CD2 expression were frequently observed in mature T-cell malignancies. The CD2 ABC values were highly sensitive in detecting differences between malignant and normal T cells (P = 0.0028). In most cases (24/32 specimens, 75%), CD2 ABCs differed by >20%. CD2 ABCs had high variability in normal T cells. Conclusions: CD2 expression by malignant T cells differed significantly from that of normal T-cells by CD2 ABC quantitation. The high variability in normal T-cell CD2 ABCs limited the determination of normal reference ranges and, thus, its utility in the diagnosis of T-cell neoplasia. However, examination of CD2 can help in detection of tumor cells when residual normal T cells are present for comparison. Moreover, the increased sensitivity of CD2 quantitation is valuable in confirming FCI cases where abnormalities in CD2 expression are difficult to appreciate by visual inspection alone. Published 2009 Wiley-Liss, Inc.