CD43 (sialophorin, leukosialin) is a heavily sialylated surface protein expressed on most leukocytes and platelets including T cells. Although CD43 antigen is known to have multiple and complex structure, exact function of CD43 in each cell type is not completely understood. Here we evaluated the role of CD43 in Fas (CD95)-induced cell death in human T lymphoblastoid cell line, Jurkat. Crosslinking CD43 antigen by K06 mAb increased the Fas-mediated Jurkat cell apoptosis and the augmentation was inhibited by treatment with caspase inhibitors. Further, CD43 signaling of Jurkat cells induced Fas oligomerization on the cell surfaces implying that CD43 ligation have effects on early stage of Fas-induced T cell death. These also suggest that CD43 might play an important role in contraction of the immune response by promotion of Fas-induced apoptosis in human T cells.
Receptor Aggregation/immunology ; Jurkat Cells ; Humans ; Caspases/metabolism ; Apoptosis/*immunology ; Antigens, Surface/metabolism ; Antigens, CD95/metabolism/*physiology ; Antigens, CD43/metabolism/*physiology ; Antibodies, Monoclonal/metabolism

Neutrophils are also known to acquire the characteristics of dendritic cells (DCs) under the appropriate conditions. In this study, neutrophils were cultivated in vitro in the presence or absence of compounds modulating their survival in an attempt to characterize the expression profile of the DC markers. Higher MHC-II, CD80, CD86, CD83, and CD40 expression levels were detected on the surface of the cultured neutrophils for 24 h than on the freshly isolated cells. The annexin V-positive cells showed a higher expression level of the DC markers than the annexin V-negative cells. The population of neutrophils double stained with annexin V and the DC markers increased after being incubated with agonistic anti-Fas Ab. LPS, the anti-apoptotic compound, decreased the CD86 and MHC-II expression levels but 50-60% of the DC marker-positive cells were detected in the annexin V-positive cells. In contrast, CD80, CD86, CD83, and HLA-DR mRNA levels increased in the GM-CSF-treated neutrophils but not in the anti-Fas Ab-treated neutrophils. T cell proliferation was inhibited by co-culturing them with anti-Fas Ab- or LPS-treated neutrophils at a high neutrophil:T cell ratio. However, the superantigen-mediated T cell proliferation was increased by the LPS-treated neutrophils but decreased by the anti-Fas Ab-treated neutrophils. There was a lower level of interferon-gamma production in the T cells co-cultured with anti-Fas Ab-treated neutrophils than with the LPS-treated neutrophils. This suggests that apoptotic neutrophils express DC markers on their surface and the differential expression of DC markers might have a detrimental effect on the immune reaction.
Antigen Presentation ; Antigens, CD/biosynthesis ; Antigens, CD95/pharmacology ; Antigens, Differentiation/*biosynthesis ; *Apoptosis ; Cells, Cultured ; Dendritic Cells/*metabolism ; Humans ; Lipopolysaccharides/pharmacology ; Lymphocyte Activation ; Neutrophils/*metabolism/physiology ; T-Lymphocytes/immunology

OBJECTIVES: To quantitate apoptosis and Fas antigen expression of T lymphocytes by activation in aplastic anemia (AA) and compare with that of normal controls and completely-recovered AA, and to investigate the apoptotic sensitivity to anti-fas antibody of activated T lymphocytes in AA. METHODS: We studied the expression of Fas antigen on fresh T lymphocytes of twenty patients with AA [13 newly diagnosed, 7 recorvered AA after immunosuppressive therapy (IST)], and investigated the activation-induced cell death (AICD) and Fas expression by activation [interleukin-2 (200 U/ml) and phytohemagglutinin (50 micrograms/ml)] in 5 newly-diagnosed AA, 5 normal controls and 5 AA in complete response (CR). Apoptotic sensitivity to anti-Fas antibody was assessed by the time-course kinetics of induction of cell death by anti-Fas antibody (500 ng/ml). RESULTS: There was no significant difference of Fas antigen expression on freshly-isolated T lymphocytes among newly-diagnosed severe AA, normal control s and patients with AA in CR after IST. In normal controls, T lymphocytes death was greatly increased at 3 days of activation, and Fas antigen expression on T lymphocytes was increased above baseline at day 1 of activation. In contrast, in newly-diagnosed AA, T lymphocytes showed delayed cell death, which correlated with a slowed increase of Fas antigen expression by activation. Also, anti-Fa s antibody sensitivity of activated T lymphocytes was decreased in newly-diagnosed AA. In completely recovered AA, these abnormal AICD and Fas antigen expressions by activation were recovered to normal range. CONCLUSIONS: Abnormal AICD plays a role in the immune pathophysiology of AA, and defective Fas system is involved in this process.
Anemia, Aplastic/pathology ; Anemia, Aplastic/immunology* ; Antigens, CD95/blood ; Apoptosis ; Case-Control Studies ; Human ; In Vitro ; Lymphocyte Transformation ; T-Lymphocytes/pathology* ; T-Lymphocytes/immunology* ; Time Factors

Sensitivity of Fas expressing tumor cells (high levels in Hut78 & Jurkat; low levels in P815) toward the cytotoxic Con-A (5 microg/ml) activated spleen cells from young (12 to 16 week old males) and old (2 year old males) mice were studied. The spleen cells from young mice activated for a day showed high levels of cytotoxic activity against Hut78 and Jurkat cell lines but not against P815 cells. The cytotoxic activity against P815 cells were detected in the spleen cells from old but not young mice following a longer period of Con-A activation (three days). Comparable levels of cytotoxic activity against Hut78 and Jurkat cells were observed in the spleen cells from both young and old mice following three days of activation. Treatment of Hut78 cells with anti-Fas antibody affected the tumor cells become resistant against the cytotoxic activity of the spleen cells from young mice in a dose dependent manner however P815 cells were not affect by the anti-Fas antibody treatment. These results show that there are differences in the sensitivity of target tumor cells toward Con-A induced cytotoxic spleen cells from young and old mouse. Mitogen-induced cytotoxic lymphocytes from young mouse spleen appear to kill targets through mechanisms involving Fas antigen, specially, in early stage (1 day) of activation. Old mouse spleen cells generated high levels of cytotoxic cells in later phase (3 days), which appear to kill through Fas-unrelated mechanisms.
Age Factors ; Animal ; Antigens, CD95/immunology* ; Cell Death/immunology ; Cells, Cultured ; Concanavalin A ; Cytotoxicity Tests, Immunologic ; Flow Cytometry ; Gene Expression Regulation/immunology ; Human ; Jurkat Cells ; Mice ; Mice, Inbred Strains ; Mitogens ; Spleen/immunology* ; T-Lymphocytes/immunology*

The changes of phospholipase D (PLD) activity were investigated during the courses of apoptotic process induced by tumor necrosis factor (TNF)-alpha or anti-Fas/Apo1 antibody in human premyelocyte HL-60 and murine B cell lymphoma A20 cells. The treatment of recombinant TNF-alpha to HL-60 cells resulted in the increased PLD activity as determined by the phosphatidylethanol formation in the presence of 1% ethanol. The enhancement of PLD activity was also observed in the anti-Fas/Apo1 monoclonal antibody-treated A20 cells. However, the activity of PLD was maximized when HL-60 and A20 cells were treated with either TNF-alpha or anti-Fas/Apo1 monoclonal antibody for 6 h. Both TNF-alpha and anti-Fas/Apo1 monoclonal antibody increased PLD activity in a dose-dependent manner up to 200 U/ml and 200 ng/ml, respectively. When the intracellular activity of protein kinase C (PKC) was interrupted by treatment of calphostin-C, both the PLD activation and the apoptosis induced by TNF-alpha and anti-Fas/Apo1 monoclonal antibody appeared to be inhibited. Since PKC is reported to activate PLD, the results indicate that the intracellular signaling cascade via PLD may play a role in the induction of apoptosis induced by TNF-alpha and anti-Fas/Apo1 monoclonal antibody.
Animal ; Antibodies, Monoclonal/pharmacology ; Antigens, CD95/metabolism* ; Antigens, CD95/immunology ; Apoptosis* ; DNA Fragmentation ; Dose-Response Relationship, Drug ; Enzyme Activation ; HL-60 Cells ; Human ; Leukemia, Promyelocytic, Acute ; Lymphoma, B-Cell ; Mice ; Naphthalenes/pharmacology ; Phospholipase D/metabolism* ; Protein Kinase C/antagonists & inhibitors ; Receptors, Tumor Necrosis Factor/metabolism* ; Signal Transduction ; Tumor Necrosis Factor/pharmacology*

Zearalenone (ZEA), a nonsteroidal estrogenic mycotoxin, is known to cause testicular toxicity in animals. In the present study, the effects of ZEA on spermatogenesis and possible mechanisms involved in germ cell injury were examined in rats. Ten-week-old Sprague-Dawley rats were treated with 5 mg/kg i.p. of ZEA and euthanized 3, 6, 12, 24 or 48 h after treatment. Histopathologically, spermatogonia and spermatocytes were found to be affected selectively. They were TUNEL-positive and found to be primarily in spermatogenic stages I-VI tubules from 6 h after dosing, increasing gradually until 12 h and then gradually decreasing. Western blot analysis revealed an increase in Fas and Fas ligand (Fas-L) protein levels in the ZEA-treated rats. However, the estrogen receptor (ER)alpha expression was not changed during the study. Collectively, our data suggest that acute exposure of ZEA induces apoptosis in germ cells of male rats and that this toxicity of ZEA is partially mediated through modulation of Fas and Fas-L systems, though ERalpha may not play a significant role.
Animals ; Antigens, CD95/*immunology ; Apoptosis/*drug effects/immunology ; Estrogens, Non-Steroidal/*toxicity ; Fas Ligand Protein/*immunology ; Histocytochemistry ; Immunoblotting ; In Situ Nick-End Labeling ; Male ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Spermatocytes/cytology/*drug effects/immunology ; Spermatogenesis/drug effects/immunology ; Spermatogonia/drug effects/immunology ; Testis/cytology/*drug effects/immunology ; Zearalenone/*toxicity

Both Fas and PMA can activate phospholipase D via activation of protein kinase Cbeta in A20 cells. Phospholipase D activity was increased 4 fold in the presence of Fas and 2.5 fold in the presence of PMA. The possible involvement of tyrosine phosphorylation in Fas-induced activation of phospholipase D was investigated. In five minute after Fas cross-linking, there was a prominent increase in tyrosine phosphorylated proteins, and it was completely inhibited by D609, a specific inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC). A tyrosine kinase inhibitor, genistein, can partially inhibit Fas-induced phospholipase D activation. There were no effects of genistein on Fas-induced activation of PC-PLC and protein kinase C. These results strongly indicate that tyrosine phosphorylation may in part account for the increase in phospholipase D activity by Fas cross-linking and D609 can block not only PC-PLC activity but also tyrosine phosphorylation involved in Fas-induced phospholipase D activation.
Animal ; Antibodies, Monoclonal/immunology/*pharmacology ; Antigens, CD95/immunology/*metabolism ; Bridged Compounds/*pharmacology ; Cell Line ; Cross-Linking Reagents ; Dose-Response Relationship, Immunologic ; Enzyme Activation ; Genistein/pharmacology ; Hydrolysis ; Lymphoma/pathology ; Mice ; Phospholipase C/*antagonists & inhibitors ; Phospholipase D/*metabolism ; Phosphorylation ; Phosphorylcholine/metabolism ; Solubility ; Thiones/*pharmacology ; Tumor Cells, Cultured ; Tyrosine/*metabolism ; Water/chemistry

Both Fas and PMA can activate phospholipase D via activation of protein kinase Cbeta in A20 cells. Phospholipase D activity was increased 4 fold in the presence of Fas and 2.5 fold in the presence of PMA. The possible involvement of tyrosine phosphorylation in Fas-induced activation of phospholipase D was investigated. In five minute after Fas cross-linking, there was a prominent increase in tyrosine phosphorylated proteins, and it was completely inhibited by D609, a specific inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC). A tyrosine kinase inhibitor, genistein, can partially inhibit Fas-induced phospholipase D activation. There were no effects of genistein on Fas-induced activation of PC-PLC and protein kinase C. These results strongly indicate that tyrosine phosphorylation may in part account for the increase in phospholipase D activity by Fas cross-linking and D609 can block not only PC-PLC activity but also tyrosine phosphorylation involved in Fas-induced phospholipase D activation.
Animal ; Antibodies, Monoclonal/immunology/*pharmacology ; Antigens, CD95/immunology/*metabolism ; Bridged Compounds/*pharmacology ; Cell Line ; Cross-Linking Reagents ; Dose-Response Relationship, Immunologic ; Enzyme Activation ; Genistein/pharmacology ; Hydrolysis ; Lymphoma/pathology ; Mice ; Phospholipase C/*antagonists & inhibitors ; Phospholipase D/*metabolism ; Phosphorylation ; Phosphorylcholine/metabolism ; Solubility ; Thiones/*pharmacology ; Tumor Cells, Cultured ; Tyrosine/*metabolism ; Water/chemistry

A20 murine lymphoma cells undergoing Fas-mediated apoptosis showed increase in the activity of phospholipase D (PLD), which is involved in proliferative or mitogenic cellular responses. Using A20 cell lines that were resistant to Fas-induced apoptosis, we investigated the differential effects of Fas cross-linking on PLD activity and sphingolipid metabolism. The basal PLD activities in all of the selected three Fas-resistant clones (#5, #8, and #11) were about 2~4 folds higher than that of wild type A20 cells. Among the PLD isoforms, PLD2 expression was increased in all of the selected Fas-resistant clones. The Fas downstream signaling events triggered by Fas cross-linking, including the activations of PLD, phosphatidy-lcholine-specific phospholipase C (PC-PLC), sphingomyelinase (SMase), the increase in diacylglycerol (DAG) and protein phosphorylation levels, and the translocation of protein kinase C to membrane were not changed in both of Fas-resistant clone #5 and #8. In contrast, Fas cross-linking stimulated the activity of PLD, PC-PLC, and SMase, translocation of PKC, and protein phosphorylation in Fas-resistant clone #11, similar to that of wild type cells. We also found that clone #11 had a different Fas sequence encoding Fas B which has been known to inhibit Fas-induced apoptosis. These findings suggest that increased PLD2 expression resulting in increased basal PLD activity and the blockade of Fas downstream signaling cascades may be involved to limit apoptosis induced by Fas cross-linking.
Animals ; Antibodies, Monoclonal/immunology/pharmacology ; Antigens, CD95/immunology/*metabolism ; Base Sequence ; Carrier Proteins/metabolism ; Clone Cells ; Cross-Linking Reagents/pharmacology ; Diglycerides/metabolism ; Enzyme Activation/drug effects ; Lipids/*metabolism ; Mice ; Molecular Sequence Data ; Phospholipase D/*metabolism ; Phosphorylation/drug effects ; Protein Kinase C/metabolism ; *Signal Transduction/drug effects ; Sphingomyelin Phosphodiesterase/metabolism ; Tumor Cells, Cultured