title: Phenotypic and functional characterization of T-BAM (CD40 ligand)+ T-cell non-Hodgkin's lymphoma.
abstract: The precise mechanisms regulating T-helper function have been intensively investigated. We and others have recently identified a new T-cell-B-cell-activating molecule called T-BAM that directs B-cell differentiation by interacting with the CD40 molecule on B cells. Using a specific monoclonal antibody against T-BAM (5C8), we have previously shown that T-BAM expressing T cells are predominantly CD4+CD8- and in normal lymphoid tissue have a unique distribution. However, no information has been obtained regarding the phenotype and functional properties of human neoplastic T cells. Therefore, we investigated T-BAM expression immunohistochemically in 87 well-characterized T-cell non-Hodgkin's lymphomas and lymphoid leukemias (LL). We found that 21/81 neoplasms expressed detectable T-BAM and these positive tumors belong almost exclusively to the CD4+CD8- subtype. In addition, to determine whether T-BAM expression could be induced on T-BAM-LL cells, we activated T-BAM-LLs in vitro and showed that T-BAM could be upregulated only in CD4+CD8- tumors. Our studies clearly show that T-BAM is constitutively expressed in a large number of T-cell neoplasms with a relative mature phenotype (CD4+CD8-) and that only CD4+ neoplastic T cells can be induced in vitro to express this molecule. Additional studies are necessary to identify the biologic significance of T-BAM expression and its potential and clinical implications.
authors.affiliation: Department of Pathology, College of Physicians and Surgeons of Columbia University, New York, NY.
authors.forename: G
authors.initials: G
authors.lastname: Inghirami
authors.forename: S
authors.initials: S
authors.lastname: Lederman
authors.forename: M J
authors.initials: MJ
authors.lastname: Yellin
authors.forename: A
authors.initials: A
authors.lastname: Chadburn
authors.forename: L
authors.initials: L
authors.lastname: Chess
authors.forename: D M
authors.initials: DM
authors.lastname: Knowles
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D023201:CD40 Ligand; D006801:Humans; D016130:Immunophenotyping; D007945:Leukemia, Lymphoid / Q000276:immunology*; D008213:Lymphocyte Activation; D016399:Lymphoma, T-Cell / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D015854:Up-Regulation
chemical_list: D008562:Membrane Glycoproteins; D023201:CD40 Ligand