Clonal T-cell expansion in patients with T-large-granular lymphocyte (LGL) leukemia occurs by an undefined mechanism that may be related to Fas apoptosis resistance. Here, we demonstrate polarized expansion of CD8(+) terminal-memory differentiation in such patients, as demonstrated by CD45RA expression and absence of CD62L expression, suggesting repeated stimulation by antigen in vivo. Eliminat...

HLA class II molecules, expressed on the surface of antigen-presenting cells, are responsible for the presentation of antigen-derived peptides to CD4+ helper T lymphocytes. Signaling via these molecules initiates the generation of second messengers leading to programed cell death (PCD) of activated B lymphocytes. The present study examined the mechanism of HLA class II-mediated apoptosis and de...

C. Giordano et al. (1) reported evidence that the ligand for Fas antigen (FasL) is constitutively expressed on thyroid follicular cells from both normal and Hashimoto’s thyroiditis (HT) tissue, and that normal thyrocytes express Fas antigen only after induction with interleukin-1b (IL-1b). Giordano et al. conclude that their results suggested a possible mechanism for thyrocyte cytotoxicity in a...

Fas, a cell surface receptor, can induce apoptosis after cross-linking with its ligand. We report that Fas antigen is constitutively expressed in medullary epithelial cells of the human thymus. Expression is decreased in cultured thymic epithelial cells (TEC), similarly to HLA-DR antigen. TEC are resistant to anti-Fas-induced apoptosis after 4 days of primary culture, and this resistance is rev...

Fas, a cell surface receptor, can induce apoptosis after cross-linking with its ligand. We report that Fas antigen is constitutively expressed in medullary epithelial cells of the human thymus. Expression is decreased in cultured thymic epithelial cells (TEC), similarly to HLA-DR antigen. TEC are resistant to anti-Fas–induced apoptosis after 4 days of primary culture, and this resistance is rev...

Fas antigen (Apo-1/CD95) is an apoptosis-signaling cell surface receptor belonging to the tumor necrosis factor receptor superfamily. Adult T cell leukemia (ATL) cells express Fas antigen and show apoptosis after treatment with an anti-Fas monoclonal antibody. We established the ATL cell line KOB, which showed resistance to Fas-mediated apoptosis, and found that KOB expressed two forms of Fas m...

Since CD40/CD40 ligand (CD40Lig) interactions are essential in vivo for the generation of germinal center B cells that express Fas (Apo-1/CD95), we explored whether CD40 engagement may modulate Fas expression and function on human B lymphocytes. Resting tonsil B cells, isolated by density gradient centrifugation, express either absent or low levels of Fas. They could be induced to promptly expr...

PURPOSE Neovascularization of the avascular cornea is a significant problem associated with many corneal diseases. Because Fas ligand (FasL) is highly expressed in the cornea, the role of this molecule in controlling corneal neovascularization was examined in this study. METHODS C57BL/6(B6), FasL (CD95L)-deficient B6-gld, and Fas (CD95)-deficient B6-lpr mice were subjected to the suture model...

To find out which cytokines are involved in the pathogenesis of multiple myeloma, we investigated cytokine receptor expression on myeloma cells using a panel of monoclonal antibodies (MoAbs). Flow cytometric analysis of five myeloma cell lines (RPMI8226, ARH77, KMM-1, U266, and Hs) and myeloma cells freshly isolated from eight patients showed that interleukin-1 receptor (IL-1R) type I and type ...

Peripheral tolerance mechanisms normally prevent delivery of T cell help to anergic self-reactive B cells that accumulate in the T zones of spleen and lymph nodes. Chronic exposure to self-antigens desensitizes B cell antigen receptor (BCR) signaling on anergic B cells so that they are not stimulated into clonal expansion by CD4(+) T cells but instead are eliminated by Fas (CD95)-induced apopto...