Syndecan-1 (CD138) expression in acute myeloblastic leukemia cells - An immuno electron microscopic study

Syndecan-1 (CD138), an important transmembrane heparan sulfate proteoglycan is expressed in distinct stages of cell differentiation. Although its expression in acute lymphoblastic leukemia (ALL) cells is well known; its function or presence in acute myeloblastic leukemia (AML) cells is still largely unknown. The expression of syndecan-1 was studied in bone marrow biopsies of three patients with AML using electron microscopic immunocytochemistry. Positive expression of syndecan-1 was found in AML cells. These results suggest that syndecan-1 expression is not only a characteristic phenotypic marker for ALL, but is also expressed in AML cells

A unique population of effector memory lymphocytes identified by CD146 having a distinct immunophenotypic and genomic profile

<p>Abstract</p> <p>Background</p> <p>CD146 is a well described homotypic adhesion molecule found on endothelial cells and a limited number of other cell types. In cells from the peripheral circulation, CD146 has also been reported to be on activated lymphocytes <it>in vitro </it>and <it>in vivo</it>. The function associated with CD146 expression on lymphoid cells is unknown and very little information is available concerning the nature of CD146+ lymphocytes. In the current study, lymphocytes from healthy donors were characterized based upon the presence or absence of CD146 expression.</p> <p>Results</p> <p>CD146 was expressed on a low percentage of circulating T lymphocytes, B lymphocytes, and NK cells in healthy individuals. CD146 expression can be induced and upregulated <it>in vitro </it>on both B cells and T cells, but does not correlate with the expression of other markers of T cell activation. CD146 positive T cells do not represent clonal expansions as determined with the use of anti Vβ reagents. Data suggest that CD146 positive cells have enhanced adherence to endothelial monolayers in vitro. Gene profiling and immunophenotyping studies between CD146+ and CD146- T cells revealed several striking genotypic distinctions such as the upregulation of IL-8 and phenotypic differences including the paucity of CCR7 and CD45RA among CD146 positive T cells, consistent with effector memory function. A number of genes involved in cell adhesion, signal transduction, and cell communication are dramatically upregulated in CD146+ T cells compared to CD146- T cells.</p> <p>Conclusion</p> <p>CD146 appears to identify small, unique populations of T as well as B lymphocytes in the circulation. The T cells have immunophenotypic characteristics of effector memory lymphocytes. The characteristics of these CD146+ lymphocytes in the circulation, together with the known functions in cell adhesion of CD146 on endothelial cells, suggests that these lymphocytes may represent a small subpopulation of cells primed to adhere to the endothelium and possibly extravasate to sites of inflammation.</p

Syndecan-1/CD138 expression in normal myeloid, acute lymphoblastic and myeloblastic leukemia cells

Stabilization of cell surface antigens and preservation of ultrastructural integrity are important aspects of immunoelectron microscopical studies. In the present study, 4 anti-syndecan-1/CD138 (B-B2, B-B4, MI15, 1D4) monoclonal antibodies (mAbs) were applied in combination with periodate-lysine-paraformaldehyde (PLP) fixation and indirect pre-embedding peroxidase electron microscopical immunocytochemistry to analyse the localization and function of these molecules in normal myeloid cells, acute lymphoblastic leukemia (ALL) cells and acute myeloblastic leukemia (AML) cells. One case of normal human bone marrow, 3 cases of untreated AML and 2 cases of untreated ALL were studied. Samples were immediately fixed for 4 h in freshly-prepared PLP fixative in 0.037 mol/L phosphate buffer, pH 7.4, containing 10 mmol/L sodium metaperiodate, 75 mmol/L lysine, and 2% paraformaldehyde. Expression of syndecan-1 was found at the plasma membrane of all cell types. Staining intensity at the membrane of AML cells was stronger than that on the membrane of normal myeloid and ALL cells. We conclude that anti-syndecan-1/CD138 mAbs in combination with the method described here are a suitable tool for detection of cell surface syndecan molecules in cells originating from progenitor cells that can differentiate in both myeloid and lymphoid cells