title: Fas ligand is not constitutively expressed in low-grade B-cell lymphoma and B-lymphoblastoid cells.
abstract: The Fas ligand (FasL) pathway is one of the two major effector mechanisms of T-cell-mediated cell death. FasL expression by extralymphatic tissues is thought to maintain a status of immunity. Accordingly, it has been proposed that tumor cells express FasL as a mechanism of immunologic escape. However, data regarding FasL expression in normal or neoplastic tissues remain controversial. In the present study, we investigated the expression of FasL in normal peripheral blood B lymphocytes or malignant cells of the B-lymphocyte lineage to elucidate a possible immunologic counterattack mechanism. FasL gene expression was analyzed by reverse transcriptase polymerase chain reaction in two non-Hodgkin's lymphoma (NHL) entities: the highly aggressive Burkitt's lymphoma (BL) and indolent NHL chronic lymphocytic leukemia (CLL). FasL expression was found to be consistently negative in all BL cell lines and purified samples from patients with CLL. FasL is not constitutively expressed in normal peripheral blood or neoplastic B lymphocytes making the Fas counterattack, as described for gastrointestinal cancer, unlikely as a mechanism of immunologic escape of lymphoma cells.
authors.affiliation: Department of Hematology and Oncology, Albert-Ludwigs University Medical Center, Freiburg, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Grüllich
authors.forename: Manfred
authors.initials: M
authors.lastname: Richter
authors.forename: Sebastian
authors.initials: S
authors.lastname: Exner
authors.forename: Jürgen
authors.initials: J
authors.lastname: Finke
mesh_terms: D015703:Antigens, CD; D001402:B-Lymphocytes / Q000737:chemistry* / Q000821:virology; D002051:Burkitt Lymphoma / Q000737:chemistry / Q000821:virology; D002469:Cell Separation; D018076:DNA, Complementary / Q000032:analysis; D053222:Fas Ligand Protein; D005434:Flow Cytometry; D015870:Gene Expression; D004854:Herpesvirus 4, Human / Q000302:isolation & purification; D018189:Immunomagnetic Separation; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism; D016393:Lymphoma, B-Cell / Q000737:chemistry*; D008562:Membrane Glycoproteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D018076:DNA, Complementary; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D012333:RNA, Messenger