Effects of interferon-α-transduced tumor cell vaccines and blockade of programmed cell death-1 on the growth of established tumors

Interferon-alpha (IFN-α) has strong antitumor effects, and IFN-α gene therapy has been used clinically against some cancers. In this study, we evaluated the efficacy of the combination of IFN-α-transduced tumor cell vaccines and programmed cell death 1 (PD-1) blockade, and investigated the mechanisms of the antitumor effects of the combined therapy. A poorly immunogenic murine colorectal cancer cell line, MC38, was transduced to overexpress IFN-α. In a therapeutic model, parental tumor-bearing mice were inoculated with MC38-IFNα cells and an anti-PD-1 antagonistic antibody. Analyses of immunohistochemistry and tumor-specific lysis were performed. The outgrowth of the established tumors was significantly reduced in mice treated with the combination of IFN-α and anti-PD-1. Immunohistochemical analyses of the therapeutic model showed marked infiltration of CD4(+) cells and CD8(+) cells in the established MC38 tumors of mice treated with both IFN-α and anti-PD-1. Significant tumor-specific cytolysis was detected when splenocytes of mice that were treated with both IFN-α and anti-PD-1 were used as effector cells. These results suggest that blockade of the PD-1 PD-ligand enhanced the Th1-type antitumor immune responses induced by IFN-α. The combination of IFN-α gene-transduced tumor cell vaccines and PD-1 blockade may be a possible candidate for a cancer vaccine for clinical trials.

Lymphotropic hepatitis C virus has an interferon-resistant phenotype

Hepatitis C virus (HCV) infects and associates with B cells, leading to abnormal B-cell activation and development of lymphoproliferative and autoimmune disorders. This immune perturbation may in turn be associated with the resistance of HCV against the host immune system. The objective of this study was to analyse the effects of HCV infection of B cells on the efficacy of interferon (IFN)-based therapy. The study enrolled 102 patients with chronic hepatitis C who were treated with pegylated IFN plus ribavirin. HCV RNA titres in B cells were compared in patients with rapid viral responder (RVR) vs non-RVR, sustained viral responder (SVR) vs non-SVR and null viral responder (NVR) vs VR. The levels of HCV RNA in B cells were significantly higher in non-RVR, non-SVR and NVR groups. Association between the therapy outcome and the positive B-cell HCV RNA was also investigated in relation to other known viral and host factors. Multivariable analyses showed that the positive B-cell HCV RNA and the minor single-nucleotide polymorphism near the IL28B gene (rs8099917) were independent factors associated with NVR in patients infected with HCV genotype 1. When these two factors were combined, the sensitivity, specificity, positive and negative predictive values for NVR were 92.3%, 98.2%, 92.3% and 98.2%, respectively. Genotype 1 and the presence of one or no mutations in the IFN-sensitivity determining region were associated with higher levels of B-cell HCV RNA. B-cell-tropic HCV appears to have an IFN-resistant phenotype. B-cell HCV RNA positivity is a predictive factor for resistance to IFN-based therapy.

Dendritic cell therapy with interferon-alpha synergistically suppresses outgrowth of established tumors in a murine colorectal cancer model

Both dendritic cell (DC)-based immunotherapy and interferon (IFN)-alpha therapy have been proved to have potent long-lasting antitumor effects. In anticipation of synergistic antitumor effects, we performed combination therapy with DCs and IFN-alpha gene-transduced murine colorectal cancer MC38 cells (MC38-IFN-alpha). DCs incubated with MC38-IFN-alpha, but not neomycin-resistance gene-transduced MC38 cells (MC38-Neo), effectively enhanced proliferation of allogeneic splenocytes in vitro. In 12 of 17 mice, DCs in combination with MC38-IFN-alpha prevented the development of a parental tumor, while DCs and MC38-Neo did in only three of 17 mice (P=0.008). In a therapeutic model of an established parental tumor, inoculation of DCs and MC38-IFN-alpha suppressed the growth of the established parental tumors significantly compared with the administration of DCs with MC38-Neo or naive splenocytes with MC38-IFN-alpha (P=0.016 and 0.024, respectively). Analyses of immunohistochemistry and tumor-infiltrating mononuclear cells showed that CD8(+), CD11c(+), and NK1.1(+) cells markedly infiltrated the established tumors of mice treated with DCs and MC38-IFN-alpha. From the results of observation of parental tumor outgrowth in immune cell-depleted mice, CD8(+) cells, and asialo-GM-1(+) cells were thought to contribute to the antitumor effects induced by the combination therapy. Furthermore, MC38-specific cytolysis was detected when splenocytes of mice inoculated with DCs and MC38-IFN-alpha cells were stimulated with MC38-IFN-alpha cells in vitro. Since DC-based immunotherapy in combination with IFN-alpha-expressing tumor cells induces potent antitumor cellular immune responses, it should be considered for clinical application.

Interleukin-4 gene transduced tumor cells promote a potent tumor-specific Th1-type response in cooperation with interferon-alpha transduction

To investigate antitumor mechanisms in interleukin (IL)-4 therapy, we established an IL-4-overexpressing MC38 murine colorectal cancer cell line (MC38-IL4). As a therapy against established tumors, MC38-IL4 cells were inoculated contralaterally 7 days after wild-type (MC38-WT) cells had been injected, significantly reducing growth of wild-type tumors (P=0.030). Immunohistochemical analysis showed numerous granulocytes infiltrating wild-type tumors of MC38-IL4-inoculated mice. Injection of MC38-IL4 cells in leukocyte-depleted mice confirmed that granulocytes were involved in IL-4-related primary antitumor effects. Inoculation of MC38-WT in leukocyte-depleted mice initially injected with MC38-IL4 suggested that T cells contributed to the antitumor effects. To investigate tumor-specific responses, we stimulated splenocytes of MC38-immune mice with MC38-IL4 cells in vitro, resulting in MC38-specific lysis (57.5+/-7.2%, effector to target ratio=20). Treatment of established wild-type tumors with MC38-IL4 in combination with interferon (IFN)-alpha-overexpressing MC38 cells (MC38-IFNalpha) significantly reduced the growth of wild-type tumors (P=0.009). In vitro IFN-gamma production by splenocytes from mice injected with both MC38-IL4 and -IFNalpha was greatly enhanced in comparison with MC38-IL4 alone, while IL-10 production was not increased. Thus, granulocytes concern early antitumor effects of IL-4 therapy. Subsequently, IL-4 induces long-lasting, tumor-specific immune responses. IL-4 appears to promote a T-helper 1-type antitumor immune response, which is enhanced in cooperation with IFN-alpha.

CC chemokine receptor-7 on dendritic cells is induced after interaction with apoptotic tumor cells: critical role in migration from the tumor site to draining lymph nodes

Dendritic cells (DCs) are very potent antigen-presenting cells and play critical roles in regulating immune responses in cancer. The migrating of DCs from the tumor site to the lymphoid organs is believed to be one of the critical events. To examine this important DC function in tumor situations, bone marrow-derived DCs, cultured for 6 days with granulocyte macrophage colony-stimulating factor and interleukin 4, were inoculated at the tumor site. We have shown (Y. Nishioka et al., Cancer Res., 59: 40354041, 1999) that DCs can migrate from tumor site to the draining lymph nodes within 24 h (approximately 0.1% of administrated DCs). The DCs then form clusters with adjacent lymphoid cells, which produce IFN-gamma (1500-3200pg/10(6) cells/48 h) in response to tumor stimulation. The number of the DCs migrating into lymph nodes were greater when they were inoculated into the tumor rather than the skin. Coculture of DCs and apoptotic tumor cells resulted in decreased expression of CC chemokine receptor (CCR) 1 and increased CCR7 expression at mRNA level without alteration in other phenotypical markers on DCs. Chemotaxis assay showed that CCR7 ligands, macrophage inflammatory protein 3beta and secondary lymphoid-tissue chemokine significantly (P < 0.05) induced the migration of DCs when cocultured with apoptotic tumor cells. To directly examine the involvement of CCR7 expression in DC migration, we investigated the functions of DCs genetically modified to express high levels of CCR7. CCR7 transduction promotes DC migration in response to relevant ligands in vitro and in vivo. These results suggest that the CCR7 expression of DCs is enhanced with direct contact with apoptotic tumor cells and may have a critical role for DC migrating to regional lymph nodes. The means to promote DC delivery to tumor and to nodal sites represent novel targets for the biological therapy of cancer.

IFN-alpha-expressing tumor cells enhance generation and promote survival of tumor-specific CTLs

IFN-alpha gene therapy has been successfully applied in several tumor models. Our studies involving the murine colorectal adenocarcinoma cell line MC38 confirm that IFN-alpha transduction of a poorly immunogenic tumor cell reduces tumorigenicity and leads to long-lasting tumor immunity. To investigate the effect of IFN-alpha transduction on the development of antitumor immune responses, we restimulated splenocytes from MC38-immune mice in vitro. Detection of MC38-specific cytotoxicity was markedly enhanced when murine IFN-alpha2-transduced MC38 (MC38-IFNalpha) or CD80-transduced MC38 (MC38-CD80) was used for restimulation compared with wild type (MC38-WT) or neomycin resistance gene-transduced MC38 (MC38-Neo) cells. MC38-specific CD8+ CTL line and clone were established from splenocytes of mouse immunized with MC38-IFNalpha. Stimulation with MC38-IFNalpha as well as MC38-CD80 enhanced the proliferation of MC38-specific CTLs in vitro much more effectively than stimulation with WT or MC38-Neo (p < 0.05). Coincubation of MC38-specific CTLs with MC38-IFNalpha or MC38-CD80 resulted in significantly less DNA fragmentation (8.0% and 12.8%, respectively) compared with coincubation of the CTLs with MC38-WT (43.5%; p < 0.001) or MC38-Neo cells (38.1%; p < 0.003). These results suggest that prevention of apoptotic cell death in tumor-specific CTLs may be one mechanism by which IFN-alpha-expressing tumor cells can promote the generation of antitumor immunity. The effect of IFN-alpha on CTLs appears to be similar to that of CD80, which also prevents apoptotic cell death after stimulation of T lymphocytes.

Interferon-alpha gene therapy in combination with CD80 transduction reduces tumorigenicity and growth of established tumor in poorly immunogenic tumor models

Interferon-alpha (IFN-alpha) or CD80 transduction of tumor cells individually reduces tumorigenicity and enhances antitumor responses. Here, we report that the combination of IFN-alpha and CD80 cancer gene therapy in poorly immunogenic murine tumor models, the colorectal adenocarcinoma cell line MC38, and the methylcholanthrene-induced fibrosarcoma cell line MCA205 reduces tumor growth more efficiently without affecting in vitro growth. Wild-type (WT), neomycin-resistance (Neo) gene-, or CD80-transduced tumor cells grew progressively in all immunocompetent mice. In contrast, IFN-alpha-transduced MC38 or MCA205 cells were rejected in 13 of 15 and seven of 15 mice, respectively. Synergistic effects were observed when IFN-alpha- and CD80-transduced tumor cells were mixed and inoculated. These admixed cells were rejected by 14 of 15 (MC38) or seven of 15 mice (MCA205), whereas, a mixture of IFN-alpha and Neo cells or CD80 and Neo cells led to tumors associated with progressive growth. Induction of long-lasting tumor immunity against WT tumor cells was demonstrated by rejection of a subsequent rechallenge in 10 of 13 (MC38) and six of seven (MCA205) tumor-free mice. The therapeutic efficacy with established WT MC38 tumors was shown when mice were treated with a vaccine consisting of repetitive injections of IFN-alpha- and CD80-transduced MC38 cells into the contralateral flank (P < 0.01). This treatment was associated with accumulation of CD4+, CD8+ cells and dendritic cells within the established tumor, demonstrating induction of antitumor immune responses. Combination gene therapy using IFN-alpha and CD80 is an effective immune therapy of cancer and could be considered for clinical trials.

IL-18 up-regulates perforin-mediated NK activity without increasing perforin messenger RNA expression by binding to constitutively expressed IL-18 receptor

IL-18 is a powerful inducer of IFN-gamma production, particularly in collaboration with IL-12. IL-18, like IL-12, also augments NK activity. Here we investigated the molecular mechanism underlying the up-regulation of killing activity of NK cells by IL-18. IL-18, like IL-12, dose dependently enhanced NK activity of splenocytes. This action was further enhanced by costimulation with IL-12. Treatment with anti-IL-2R Ab did not affect IL-18- and/or IL-12-augmented NK activity, and splenocytes from IFN-gamma-deficient mice showed enhanced NK activity following stimulation with IL-12 and/or IL-18. Splenocytes from the mice deficient in both IL-12 and IL-18 normally responded to IL-18 and/or IL-12 with facilitated NK activity, suggesting that functional NK cells develop in the absence of IL-12 and IL-18. IL-18R, as well as IL-12R mRNA, was constitutively expressed in splenocytes from SCID mice, which lack T cells and B cells but have intact NK cells, and in those from IL-12 and IL-18 double knockout mice. NK cells isolated from SCID splenocytes expressed IL-18R on their surface. IL-18, in contrast to IL-12, did not enhance mRNA expression of perforin, a key molecule for exocytosis-mediated cytotoxicity. However, pretreatment with concanamycin A completely inhibited this IL-18- and/or IL-12-augmented NK activity. Furthermore, IL-18, like IL-12, failed to enhance NK activity of splenocytes from perforin-deficient mice. These data suggested that NK cells develop and express IL-12R and IL-18R in the absence of IL-12 or IL-18, and that both IL-18 and IL-12 directly and independently augment perforin-mediated cytotoxic activity of NK cells.

[Successful treatment for disseminated intra-vascular coagulation due to sepsis and brain abscess with low molecular weight heparin in a patient with antiphospholipid syndrome]

The management of disseminated intravascular coagulation (DIC) in a 22-year-old female patient with antiphospholipid syndrome is reported. Gabexate mesilate was given by continuous drip infusion at 1.5 g/day. No effect was seen, therefore Dalteparin sodium (DS) was administered by continuous drip infusion at 70 U/kg/day. The DIC score improved gradually during the first 4 days to normalization by 10 days. However, convulsive seizure was developed. Computed tomographic scan of brain demonstrated brain abscess at lt-basal ganglia. Continuous drainage was performed while administered continuous drip infusion of DS. Follow-up CT after operation showed reduction of low density area which means brain abscess. Finding in this case suggest that DS may play a role in the management of DIC accompanying intracranial infection.

Effect of bucladesine sodium on the plasma concentrations and urinary excretion of purine bases and uridine

To examine whether bucladesine sodium affects the plasma concentrations of purine bases (hypoxanthine, xanthine, and uric acid) and uridine, 100 mL of physiological saline containing bucladesine sodium (6 mg/kg weight) was administered intravenously to eight healthy subjects for 1 hour after overnight fast except for water. Blood was drawn 30 minutes before, and 30 minutes and 1 hour after the beginning of the infusion, and 1-hour urine was collected before and after the beginning of the infusion. Two weeks later, 100 mL of only physiological saline was administered under the same protocol. Bucladesine sodium decreased the plasma concentrations of hypoxanthine by 36% and by 37%, and of xanthine by 16% and 33%, and of uridine by 17% and 30%, 30 minutes and 1 hour after the beginning of the infusion, respectively, and increased the urinary excretion of hypoxanthine and uric acid by 140% and 30%, respectively, after the beginning of the infusion. However, it did not affect the plasma concentration of uric acid or the urinary excretion of xanthine, and the urinary excretion of uridine was less than 0.2 micromol/h before or after bucladesine sodium infusion. On the other hand, physiological saline alone did not affect any of the values described. These results suggest that bucladesine sodium acts on the secretory process of the renal transport of hypoxanthine, resulting in the increased urinary excretion of hypoxanthine, and further suggest that bucladesine sodium enhances the uptake of uridine in plasma to liver cells.

Effect of glucagon on the plasma concentration of uridine

To determine whether glucagon affects the plasma concentration of uridine, we administered 100 mL physiological saline containing 1 mg glucagon or 100 mL physiological saline alone intravenously over 1 hour to healthy subjects. Glucagon decreased the plasma concentration of uridine from 5.72 +/- 1.05 to 4.80 +/- 0.60 micromol/L but increased the concentrations of cyclic adenosine monophosphate (cAMP) in plasma and pyruvic acid and lactic acid in blood 59-, 1.4-, and 1.3-fold, respectively. Although glucagon increased urinary excretion of uric acid, it did not affect the plasma concentration of purine bases (hypoxanthine, xanthine, and uric acid) or urinary excretion of oxypurines and uridine, indicating that glucagon does not affect purine degradation and suggesting that glucagon does not affect adenosine triphosphate (ATP) consumption-induced pyrimidine degradation. In contrast, physiological saline did not affect any of the measured variables. These results suggest that glucagon enhanced Na+-dependent uridine uptake from the blood into the cells, since glucagon stimulates Na+-dependent uridine uptake into cells in vitro.

Xylitol-induced increase in the plasma concentration and urinary excretion of uridine and purine bases

To determine whether xylitol increases the plasma concentration and urinary excretion of uridine together with purine bases, we administered xylitol (0.6 g/kg weight) intravenously to six normal subjects using a 10% xylitol solution. Xylitol infusion increased the plasma concentration and urinary excretion of uridine, as well as purine bases, while it decreased both the concentrations of inorganic phosphate in plasma and pyruvic acid in blood and increased the blood concentration of lactic acid. These results suggest that an increase in the plasma concentration and urinary excretion of uridine is ascribable to increased pyrimidine degradation following purine degradation induced by xylitol.

Impaired induction of cytotoxic T lymphocytes by antagonism of a weak agonist borne by a variant hepatitis C virus epitope

An epitope that acted as a weak agonist in the cytotoxicity assay was identified as part of the capsid protein of a hepatitis C virus (HCV) variant. In a low concentration, the variant epitope also had a weak antagonistic effect. When a minute amount of this variant epitope was added to the culture for induction, it selectively attenuated the expansion of major cytotoxic T cell populations and drastically reduced the cytotoxic responses against the wild-type epitope. Thus, antagonism to induction suppressed immune responses against both the wild type and the variant, thereby helping the persistence of not only variant itself but also the wild-type HCV. Because this variant was a weak agonist, most cytotoxic T cells induced with the wild-type epitope were cross-reactive with the variant and susceptible to the antagonism to induction. Only the T cells which were not cross-reactive with the variant and not susceptible to the antagonism survived the antagonism in induction. This implied that the specificity of the remaining immune response, if any, was directed exclusively to the wild-type epitope after the emergence of the variant. For viruses like HCV, being heterogeneous itself may contribute significantly toward persistent infection through antagonism to induction.

Propionibacterium acnes treatment diminishes CD4+ NK1.1+ T cells but induces type I T cells in the liver by induction of IL-12 and IL-18 production from Kupffer cells

LPS injection into normal mice does not induce liver injury, while the same treatment of Propionibacterium acnes-primed mice induces severe liver injury, indicating that P. acnes treatment renders the mice susceptible to LPS. Since IFN-gamma sensitizes macrophages to LPS, we investigated the mechanism of induction and activation of IFN-gamma-producing (type 1) T cells by P. acnes. Twenty percent of liver lymphocytes of C57BL/6 mice are CD4+ NK1.1+ T cells that promptly produce IL-4 in response to anti-CD3 in vitro. However, P. acnes treatment diminished these lymphocytes. Therefore, liver lymphocytes from P. acnes-primed mice showed reduced IL-4 production. Furthermore, P. acnes treatment induced CD4- type 1 T cells in the liver. Isolated P. acnes-elicited Kupffer cells produced IL-12 and to a lesser degree IL-18 in vitro. Injection of anti-IL-12 Ab totally abrogated these actions of P. acnes, while injection of anti-IL-18 Ab caused only partial abrogation. Thus, administration of P. acnes diminished CD4+ NK1.1+ T cells, but induced type 1 T cells in the liver by induction of IL-12 and IL-18 production. Injection of IL-12 (approximately 1,000 ng) dose dependently diminished CD4+ NK1.1+ T cells, but induced type 1 T cells. In contrast, injection of IL-18 (approximately 1,000 ng) failed, although injection of a much larger dose of IL-18 (10,000 ng) or IL-18 (approximately 1,000 ng) with suboptimal doses of IL-12 (1-100 ng) diminished CD4+ NK1.1+ T cells in a dose-dependent manner. Thus, P. acnes treatment renders the mice highly susceptible to LPS by induction and activation of type 1 T cells.

Propionibacterium acnes treatment diminishes CD4+ NK1.1+ T cells but induces type I T cells in the liver by induction of IL-12 and IL-18 production from Kupffer cells

LPS injection into normal mice does not induce liver injury, while the same treatment of Propionibacterium acnes-primed mice induces severe liver injury, indicating that P. acnes treatment renders the mice susceptible to LPS. Since IFN-gamma sensitizes macrophages to LPS, we investigated the mechanism of induction and activation of IFN-gamma-producing (type 1) T cells by P. acnes. Twenty percent of liver lymphocytes of C57BL/6 mice are CD4+ NK1.1+ T cells that promptly produce IL-4 in response to anti-CD3 in vitro. However, P. acnes treatment diminished these lymphocytes. Therefore, liver lymphocytes from P. acnes-primed mice showed reduced IL-4 production. Furthermore, P. acnes treatment induced CD4- type 1 T cells in the liver. Isolated P. acnes-elicited Kupffer cells produced IL-12 and to a lesser degree IL-18 in vitro. Injection of anti-IL-12 Ab totally abrogated these actions of P. acnes, while injection of anti-IL-18 Ab caused only partial abrogation. Thus, administration of P. acnes diminished CD4+ NK1.1+ T cells, but induced type 1 T cells in the liver by induction of IL-12 and IL-18 production. Injection of IL-12 (approximately 1,000 ng) dose dependently diminished CD4+ NK1.1+ T cells, but induced type 1 T cells. In contrast, injection of IL-18 (approximately 1,000 ng) failed, although injection of a much larger dose of IL-18 (10,000 ng) or IL-18 (approximately 1,000 ng) with suboptimal doses of IL-12 (1-100 ng) diminished CD4+ NK1.1+ T cells in a dose-dependent manner. Thus, P. acnes treatment renders the mice highly susceptible to LPS by induction and activation of type 1 T cells.

Perforin, Fas/Fas ligand, and TNF-alpha pathways as specific and bystander killing mechanisms of hepatitis C virus-specific human CTL

In chronic hepatitis C, Fas expression is up-regulated in the hepatocytes, especially near liver-infiltrating lymphocytes, and Fas ligand is expressed on the lymphocytes. The presence of hepatitis C virus (HCV)-specific CTLs has been demonstrated both in peripheral blood and among liver-infiltrating lymphocytes of patients with chronic hepatitis C. We studied the killing mechanisms of HCV-specific human CTLs using target cells that were sensitive or resistant to agonistic anti-Fas Abs and TNF-alpha. We show that HCV-specific CTL clones kill non-Ag-bearing bystander cells as well as Ag-bearing cells, although the bystander killing is less efficient than the specific target cell killing, and the efficacy of the bystander killing of anti-Fas- and soluble TNF-alpha-sensitive cells is greater than that of resistant cells. We also show that the killing of Ag-presenting, sensitive cells is mediated by Fas ligand and TNF-alpha as well as perforin, although the latter plays a major role in the killing at a low E:T ratio, and that the killing of sensitive bystander cells is primarily mediated by Fas ligand and TNF-alpha on CTLs expressed upon specific Ag stimulation, which may be relevant to the bystander lysis by HCV-specific CTLs of uninfected hepatocytes, in which Fas expression is up-regulated. Activated CTLs also kill bystander cells by the perforin-based mechanism, although it requires a high E:T ratio. The effective bystander killing requires a close intercellular contact between CTLs and target cells, although TNF-alpha released from the CTLs mediates lysis of the bystander cells without a close cell-cell contact.

Perforin, Fas/Fas ligand, and TNF-alpha pathways as specific and bystander killing mechanisms of hepatitis C virus-specific human CTL

In chronic hepatitis C, Fas expression is up-regulated in the hepatocytes, especially near liver-infiltrating lymphocytes, and Fas ligand is expressed on the lymphocytes. The presence of hepatitis C virus (HCV)-specific CTLs has been demonstrated both in peripheral blood and among liver-infiltrating lymphocytes of patients with chronic hepatitis C. We studied the killing mechanisms of HCV-specific human CTLs using target cells that were sensitive or resistant to agonistic anti-Fas Abs and TNF-alpha. We show that HCV-specific CTL clones kill non-Ag-bearing bystander cells as well as Ag-bearing cells, although the bystander killing is less efficient than the specific target cell killing, and the efficacy of the bystander killing of anti-Fas- and soluble TNF-alpha-sensitive cells is greater than that of resistant cells. We also show that the killing of Ag-presenting, sensitive cells is mediated by Fas ligand and TNF-alpha as well as perforin, although the latter plays a major role in the killing at a low E:T ratio, and that the killing of sensitive bystander cells is primarily mediated by Fas ligand and TNF-alpha on CTLs expressed upon specific Ag stimulation, which may be relevant to the bystander lysis by HCV-specific CTLs of uninfected hepatocytes, in which Fas expression is up-regulated. Activated CTLs also kill bystander cells by the perforin-based mechanism, although it requires a high E:T ratio. The effective bystander killing requires a close intercellular contact between CTLs and target cells, although TNF-alpha released from the CTLs mediates lysis of the bystander cells without a close cell-cell contact.

Effect of ethanol and fructose on plasma uridine and purine bases

To determine whether both ethanol and fructose increase the plasma concentration of uridine, we administered ethanol (0.6 g/kg) or fructose (1.0 g/kg) to seven normal subjects. Both ethanol and fructose increased the plasma concentration of uridine together with an increase in the plasma concentration of oxypurines, whereas fructose also increased the plasma concentration of uric acid, but ethanol did not. In ethanol ingestion and fructose infusion, an increase in the plasma concentration of purine bases correlated with that of uridine. These results strongly suggest that an increase in the plasma concentration of uridine is ascribable to increased pyrimidine degradation following purine degradation increased by ethanol and fructose.

Effect of glucagon on renal excretion of oxypurinol and purine bases

OBJECTIVE

To investigate whether glucagon increases the urinary excretion of oxypurinol and purine bases.

METHODS

We administered 1 mg glucagon intravenously to 5 healthy subjects taking 300 mg allopurinol orally, and determined plasma concentrations and urinary excretion of oxypurinol and purine bases.

RESULTS

Glucagon increased the urinary excretion and fractional clearances of uric acid, xanthine, and oxypurinol, together with an increase in creatinine clearance, while it decreased plasma concentrations of xanthine and hypoxanthine.

CONCLUSION

Glucagon-induced increases in urinary excretion of uric acid, xanthine, and oxypurinol were attributable to increases in the fractional clearances of uric acid, xanthine, and oxypurinol in addition to an increase in glomerular filtration rate. It is suggested that glucagon affects the renal common transport pathway of uric acid, xanthine, and oxypurinol by stimulating the release of a liver derived renal vasodilator.

Cytotoxic T lymphocyte response and viral load in hepatitis C virus infection

A cytotoxic T lymphocyte (CTL) response to the hepatitis C virus (HCV) nucleoprotein residues 88-96 that are the minimal and optimal epitope for human leukocyte antigen (HLA) B44-restricted CTLs was assessed in 27 HLA B44-positive patients with chronic HCV infection. Serum HCV RNA concentration and the amino acid sequence of the residues 81-100 were also determined. Three patients were infected with HCV with uncommon amino acid substitutions within the epitope. One was infected with HCV with an amino acid substitution in the flanking residues of the epitope. To stimulate CTLs in the peripheral blood, 9-mer peptides that corresponded to the residues 88-96 of the individual patients were synthesized and used. Seven of the 27 patients demonstrated a CTL response to the residues 88-96 with specific cytotoxic activities higher than 20%. The CTL activities were significantly higher in patients with a low titer of serum HCV RNA than in those with a high titer of serum HCV RNA (P = .0006). Some of the patients that demonstrated a CTL response to the residues 88-96 also demonstrated a CTL response to a newly identified HLA B44-restricted CTL epitope or a known HLA A11-restricted CTL epitope or both. No apparent association was observed between the CTL response and the stage of disease, or between the CTL response and the grade of necroinflammatory activity. The results suggest that the HLA B44-restricted CTLs together with other HCV-specific CTLs may inhibit the outgrowth of HCV and that high-titer infection with HCV may suppress the CTL responses.

Determination of human plasma xanthine oxidase activity by high-performance liquid chromatography

An assay for human plasma xanthine oxidase activity was developed with pterin as the substrate and the separation of product (isoxanthopterin) by high-performance liquid chromatography with a fluorescence detector. The reaction mixture consists of 60 microliters of plasma and 240 microliters of 0.2 M Tris-HCl buffer (pH 9.0) containing 113 microM pterin. With this assay, the activity of plasma xanthine oxidase could be easily determined despite its low activity. As a result, it could be demonstrated that the intravenous administration of heparin or the oral administration of ethanol did not increase plasma xanthine oxidase activity in normal subjects, and also that plasma xanthine oxidase activity was higher in patients with hepatitis C virus infection than in healthy subjects or patients with gout. In addition, a single patient with von Gierke's disease showed a marked increase in the plasma activity of this enzyme, relative to that apparent in normal subjects.

Three new cytotoxic T cell epitopes identified within the hepatitis C virus nucleoprotein

Cytotoxic T lymphocytes (CTLs) may play a role in host defence against hepatitis C virus (HCV) infection, and HCV-specific CTL epitopes may be included in vaccines to induce protective CTLs. We identified three new epitopes within the HCV nucleoprotein recognized by CTLs. HCV nucleoprotein residues 28-37 are the minimal epitope recognized by CTLs in association with the class I human leukocyte antigen B60, and epitopes in HCV nucleoprotein residues 111-130 and 161-180 are both recognized by CTLs in association with the class II human leukocyte antigen DRBI*08032.

HLA B44-restricted cytotoxic T lymphocyte responses to the peptides of HCV nucleoprotein residues 81-100 in patients with chronic hepatitis C

Human leukocyte antigen B44-restricted cytotoxic T lymphocytes (CTLs) recognize an epitope in hepatitis C virus (HCV) nucleoprotein residues 81-100. CTLs that recognize two wild-type peptides 81-100 of HCV genotypes 1b/II and 2a/III were generated from peripheral blood lymphocytes of each of three patients studied. Although CTLs that recognize a wild-type peptide 81-100 of HCV genotypes 1a/I and 2b/IV were not generated from any patient, CTLs that recognize peptide 81-100 of a rare HCV isolate of type 1a/I were generated from two patients. The results suggest that HLA B44-restricted CTLs recognize most, if not all, HCV isolates of types 1b/II and 2a/III and rare variants of type 1a/I and that the wild-type HCV isolates of genotypes 1a/I and 2b/IV may be less immunogenic for HLA B44-restricted CTLs.

A minimal and optimal cytotoxic T cell epitope within hepatitis C virus nucleoprotein

Amino acid residues 81-100 of the hepatitis C virus (HCV) nucleoprotein contain a cytotoxic T cell epitope that is recognized by cytotoxic T lymphocytes (CTLs) in association with human leukocyte antigen B44. With panels of truncated and overlapping peptides, the minimal and optimal epitope recognized by CTLs was shown to be a 9-mer peptide (residues 88-96). The peptide can stimulate effectively CTLs that are able to recognize endogenously synthesized and processed HCV nucleoprotein.

Determination of plasma purine nucleoside phosphorylase activity by high-performance liquid chromatography

A high-performance liquid chromatographic method was developed for the determination of plasma purine nucleoside phosphorylase activity. In this method, the reaction mixture consisted of 15 microliters of plasma and 285 microliters of 50 mM phosphate buffer (pH 7.4) containing 3.8 mM inosine and 0.15 mM 2-(3-cyano-4-isobutoxyphenyl)-4-methyl-5-thiazolecarboxylic acid (strong xanthine oxidase inhibitor). After the reaction, the hypoxanthine produced was monitored to express plasma purine nucleoside phosphorylase activity. By this method, the activity of purine nucleoside phosphorylase was easily determined even with a small-volume plasma sample and despite its low activity in plasma. In addition, plasma purine nucleoside phosphorylase activity can be accurately determined even if the plasma is turbid. As a result, we were able to measure plasma purine nucleoside phosphorylase activity in patients with gout or asthma and healthy subjects, whereby it was demonstrated that plasma purine nucleoside phosphorylase activity was higher in patients with asthma than in either healthy subjects or patients with gout.

A helper T-cell antigen enhances generation of hepatitis C virus-specific cytotoxic T lymphocytes in vitro

A T-cell helper for generation of hepatitis C virus-specific cytotoxic T lymphocytes was studied in three patients with chronic hepatitis C. In all three, human leukocyte antigen B44-restricted cytotoxic T lymphocytes recognizing an epitope in hepatitis C virus nucleocapsid protein residues 81-100 were generated from the peripheral blood lymphocytes by repeated stimulation with a synthetic hepatitis C virus nucleocapsid peptide. The proliferative response of peripheral blood lymphocytes to hepatitis C virus nucleocapsid protein residues 1-120 was observed in one patient, and was ascribed to CD4+ T cells. The helper T cells recognized a major epitope in residues 21-40 and a minor epitope(s) in residues 81-110. They produced interferon gamma, but interleukin 4 was not detectable in the T-helper cell culture supernatants. The hepatitis C virus nucleocapsid protein residues 1-120 and the major helper T-cell epitope enhanced generation of hepatitis C virus-specific cytotoxic T lymphocytes in vitro, although the protein alone did not generate them. In the other two patients, the protein did not enhance generation of hepatitis C virus-specific cytotoxic T lymphocytes in vitro. The results suggest that a hepatitis C virus-specific helper T-cell epitope is helpful for inducing a strong specific cytotoxic T-lymphocyte response.

Identification and characterization of IL-2 hyper-responsive NZB/WF1 CD5- B cells

The responsiveness of CD5- and CD5+ B cells of BALB/c and NZB/WF1 mice to various cytokines was examined with respect to their growth and differentiation. BALB/c splenic CD5- B cells required longer incubation with IL-2 or pretreatment with IL-4 to respond to IL-2 by DNA synthesis, whereas NZB/WF1 CD5- B cells were highly competent to IL-2. Flow cytometric analysis demonstrated that NZB/WF1 and BALB/c CD5- B cells had higher and intermediate proportions of B cells positive for IL-2R beta, respectively. On the other hand, BALB/c and NZB/WF1 splenic CD5+ B cells consisted of lower proportion of B cells positive for IL-2R beta than did their corresponding CD5- B cells and grew meagerly in response to IL-2. Peritoneal exudative CD5+ B cells of NZB/WF1 mice lacked IL-2R beta mRNA expression and failed to respond to IL-2. Although both BALB/c and NZB/WF1 CD5- B cells pretreated with anti-IgM, IL-4, and IL-5 responded to IL-2 by DNA synthesis, only BALB/c CD5- B cells developed into IgM-producing cells. Furthermore, BALB/c, but not NZB/WF1 CD5-, B cells pretreated with anti-IgM and IL-5 responded to IL-2 by IgM production without DNA synthesis. Thus, cross-talk between IL-4 and IL-2 operated in the growth responses of both BALB/c and NZB/WF1 splenic CD5- B cells, whereas cross-talk between IL-5 and IL-2 operated only in the differentiation of BALB/c CD5- B cells, providing us with another intriguing functional abnormality of NZB/WF1 B cells.

Identification and characterization of IL-2 hyper-responsive NZB/WF1 CD5- B cells

The responsiveness of CD5- and CD5+ B cells of BALB/c and NZB/WF1 mice to various cytokines was examined with respect to their growth and differentiation. BALB/c splenic CD5- B cells required longer incubation with IL-2 or pretreatment with IL-4 to respond to IL-2 by DNA synthesis, whereas NZB/WF1 CD5- B cells were highly competent to IL-2. Flow cytometric analysis demonstrated that NZB/WF1 and BALB/c CD5- B cells had higher and intermediate proportions of B cells positive for IL-2R beta, respectively. On the other hand, BALB/c and NZB/WF1 splenic CD5+ B cells consisted of lower proportion of B cells positive for IL-2R beta than did their corresponding CD5- B cells and grew meagerly in response to IL-2. Peritoneal exudative CD5+ B cells of NZB/WF1 mice lacked IL-2R beta mRNA expression and failed to respond to IL-2. Although both BALB/c and NZB/WF1 CD5- B cells pretreated with anti-IgM, IL-4, and IL-5 responded to IL-2 by DNA synthesis, only BALB/c CD5- B cells developed into IgM-producing cells. Furthermore, BALB/c, but not NZB/WF1 CD5-, B cells pretreated with anti-IgM and IL-5 responded to IL-2 by IgM production without DNA synthesis. Thus, cross-talk between IL-4 and IL-2 operated in the growth responses of both BALB/c and NZB/WF1 splenic CD5- B cells, whereas cross-talk between IL-5 and IL-2 operated only in the differentiation of BALB/c CD5- B cells, providing us with another intriguing functional abnormality of NZB/WF1 B cells.

Effect of BOF-4272 on the oxidation of allopurinol and pyrazinamide in vivo. Is xanthine dehydrogenase or aldehyde oxidase more important in oxidizing both allopurinol and pyrazinamide?

Allopurinol or pyrazinamide was administered to rats treated with BOF-4272 (a potent xanthine oxidase inhibitor) to investigate to what degree xanthine dehydrogenase participates in the oxidation of these agents. BOF-4272 markedly decreased the plasma concentration and the urinary excretion of both oxypurinol and 5-hydroxypyrazinamide. It also decreased the sum of the urinary excretion of allopurinol and oxypurinol and that of pyrazinamide and its metabolites, although it did not affect the sum of the plasma concentrations of allopurinol and oxypurinol at 105 min after administration of allopurinol or the plasma concentration of pyrazinamide during the period after the administration of pyrazinamide. These results suggested that BOF-4272 almost completely inhibited the oxidation of allopurinol and pyrazinamide and had some effect on the excretion and/or the tissue incorporation of these two compounds. Since the in vitro study demonstrated that BOF-4272 did not inhibit the activity of aldehyde oxidase, which oxidized both allopurinol to oxypurinol and pyrazinamide to 5-hydroxypyrazinamide, the results suggested that xanthine dehydrogenase was the more important enzyme in converting allopurinol to oxypurinol and pyrazinamide to 5-hydroxypyrazinamide.

Determination of erythrocyte aldehyde dehydrogenase activity by high-performance liquid chromatography

An ion-paired high-performance liquid chromatographic method was developed for the determination of erythrocyte aldehyde dehydrogenase activity. This method does not require pretreatment to remove hemoglobin from the hemolysate before enzyme reaction is initiated. In addition, the advantage with this high-performance liquid chromatographic method is that erythrocyte aldehyde dehydrogenase activity can be measured using whole blood without either separation or washing of erythrocytes. Therefore, it can be easily used in the determination of erythrocyte aldehyde dehydrogenase activity, which is an indication of excess alcohol consumption.

In vitro oxidation of pyrazinamide and allopurinol by rat liver aldehyde oxidase

Aldehyde oxidase was purified about 120-fold from rat liver cytosol by sequential column chromatography using diethylaminoethyl (DEAE) cellulose, Benzamidine-Sepharose 6B and gel filtration. The purified enzyme was shown as a single band with M(r) of 2.7 x 10(5) on polyacrylamide gel electrophoresis (PAGE) and M(r) of 1.35 x 10(5) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Using this purified enzyme, in vitro conversion of allopurinol, pyrazinamide and pyrazinoic acid was investigated. Allopurinol and pyrazinamide were oxidized to oxypurinol and 5-hydroxy-pyrazinamide, respectively, while pyrazinoic acid, the microsomal deamidation product of pyrazinamide, was not oxidized to 5-hydroxypyrazinoic acid. The apparent Km value of the enzyme for pyrazinamide was 160 microM and that for allopurinol was 1.1 mM. On PAGE, allopurinol- or pyrazinamide-stained band was coincident with Coomassie Brilliant Blue R 250-stained band, respectively. These results suggest that aldehyde oxidase may play a role in the oxidation of allopurinol to oxypurinol and that of pyrazinamide to 5-hydroxypyrazinamide with xanthine dehydrogenase which can oxidize both allopurinol and pyrazinamide in vivo. The aldehyde oxidase may also play a major role in the oxidation of allopurinol and pyrazinamide in the subgroup of xanthinuria patients (xanthine oxidase deficiency) who can oxidize both allopurinol and pyrazinamide.

Xylitol-induced increase in purine degradation: a role of erythrocytes

We administered xylitol intravenously to normal subjects to investigate the mechanism of xylitol-induced increase in the purine degradation in humans. Xylitol increased the plasma concentrations of hypoxanthine, xanthine and uric acid but decreased the blood concentration of pyruvic acid. The erythrocyte concentrations of IMP, AMP, ADP, glyceraldehyde 3-phosphate and fructose 1,6-diphosphate as well as the urinary excretion of hypoxanthine and xanthine were increased, while the erythrocyte concentration of ATP was decreased. In addition, the in vitro incubation studies using erythrocytes demonstrated that both xylitol-induced purine degradation and xylitol-induced inhibition of the conversion of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate were protected by pyruvic acid. These results indicate that xylitol-induced impairment of glycolysis in erythrocytes contributes to the observed xylitol-induced increase in the purine degradation in the body.

High serum IL-6 level reflects susceptible status of the host to endotoxin and IL-1/tumor necrosis factor

Patients with high level of serum endotoxin did not necessarily develop into lethal shock, whereas some patients died of septic shock even when their serum endotoxin levels were low. These results indicate that limiting factor which determines the host to be endotoxin shock principally depends on the host susceptibility to endotoxin instead of serum endotoxin level. To understand this susceptible status of the host to endotoxin, we used Propionibacterium acnes primed mouse endotoxin shock model. We found that P. acnes-primed mice responded to low dose of LPS by enhanced production of IL-1 and TNF. And such mice were highly susceptible to the lethal shock inducing effect of IL-1 and/or TNF, which also induced high level of serum IL-6 in these mice. Therefore, measurement of serum IL-6 level provides us with the information of the preceding exposure of the host to either LPS or IL-1 and/or TNF and the highly susceptible status of the host to these stimuli. Based on these results obtained from animal model, we investigated the relationship between serum IL-6 levels and serum endotoxin levels in the patients with malignant hematologic disorders. We found that these patients fell into two groups; an endotoxin susceptible group, equivalent to P. acnes-primed mice, showing high level of serum IL-6 with low level of serum endotoxin, and a nonendotoxin susceptible group, equivalent to P. acnes-nonprimed mice, showing low or undetectable level of serum IL-6 with high level of serum endotoxin. We propose that the measurement of serum IL-6 level in the patients positive for endotoxin is a useful tool in evaluating diagnosis and prognosis of endotoxin shock.

High serum IL-6 level reflects susceptible status of the host to endotoxin and IL-1/tumor necrosis factor

Patients with high level of serum endotoxin did not necessarily develop into lethal shock, whereas some patients died of septic shock even when their serum endotoxin levels were low. These results indicate that limiting factor which determines the host to be endotoxin shock principally depends on the host susceptibility to endotoxin instead of serum endotoxin level. To understand this susceptible status of the host to endotoxin, we used Propionibacterium acnes primed mouse endotoxin shock model. We found that P. acnes-primed mice responded to low dose of LPS by enhanced production of IL-1 and TNF. And such mice were highly susceptible to the lethal shock inducing effect of IL-1 and/or TNF, which also induced high level of serum IL-6 in these mice. Therefore, measurement of serum IL-6 level provides us with the information of the preceding exposure of the host to either LPS or IL-1 and/or TNF and the highly susceptible status of the host to these stimuli. Based on these results obtained from animal model, we investigated the relationship between serum IL-6 levels and serum endotoxin levels in the patients with malignant hematologic disorders. We found that these patients fell into two groups; an endotoxin susceptible group, equivalent to P. acnes-primed mice, showing high level of serum IL-6 with low level of serum endotoxin, and a nonendotoxin susceptible group, equivalent to P. acnes-nonprimed mice, showing low or undetectable level of serum IL-6 with high level of serum endotoxin. We propose that the measurement of serum IL-6 level in the patients positive for endotoxin is a useful tool in evaluating diagnosis and prognosis of endotoxin shock.

Role and regulation of interleukin (IL)-2 receptor alpha and beta chains in IL-2-driven B-cell growth

Substantial proportions of resting B cells constitutively express low levels of IL-2 receptor (IL-2R) alpha and/or beta chains. The expression of these chains is differentially regulated by anti-IgM and IL-2/IL-4. The anti-IgM induces IL-2R alpha chain expression, whereas each of the two cytokines induces IL-2R beta chain expression in a dose-dependent manner. Moreover, IL-2 induces the growth of B cells, when the cells were pretreated with IL-2 or IL-4 for 24 h. The magnitude of this IL-2-driven B-cell growth depends upon the level of IL-2R beta chain expression. Costimulation of the B cells with IL-2 and anti-IgM shifts the dose-response curve, and the cells proliferate at an IL-2 concentration as low as 40 pM. These results indicate that the levels of anti-IgM-induced IL-2R alpha chain and IL-2-induced IL-2R beta chain determine the sensitivity of the cells to IL-2.

Theophylline-induced increase in plasma uric acid--purine catabolism increased by theophylline

The effect of theophylline on the concentration of uric acid in plasma was investigated. Theophylline increased the plasma concentrations of purine bases (uric acid, hypoxanthine and xanthine) without a decreased urinary excretion of these purine bases in normal subjects. 1-methyl uric acid, a metabolite of theophylline, was not converted to uric acid in a detectable level by the hepatoma-derived cell line HuH-7 cells. Although theophylline affected neither the concentration of nucleotides nor the activities of the enzymes related to purine metabolism (hypoxanthine-guanine phosphoribosyl transferase, 5'-nucleotidase, adenosine deaminase and purine nucleoside phosphorylase) in erythrocytes, these results suggested that theophylline-induced purine degradation seems to be a cause of the increased concentration of uric acid in plasma.

Defective lectin-induced p55kDa-IL2R expression on peripheral T cells in non-Hodgkin's lymphoma patients

We examined 19 non-Hodgkin's lymphoma patients for their responsiveness to lectin stimulation, as measured by T cell proliferative response and p55kDa-IL2R expression. Our results indicate that both these responses were remarkably depressed in non-Hodgkin's lymphoma patients and the deficiency of lectin-induced p55kDa-IL2R expression correlated closely with the reductions in the lectin-induced T cell proliferative responses. The evidence that costimulation with PMA can partially overcome the IL2R defect might allow us to localize the cellular defects and rationally design chemotherapeutic agents corrective for these patients' poor p55kDa-IL2R inducibility.

Lymphokine-regulated differential expression of mRNA for p75kDa-IL-2R and p55kDa-IL-2R in a cloned B lymphoma line (BLC1-CL-3 cells)

IL-5 renders BCL1-CL-3 (CL-3) cells responsive to IL-2 by increasing the number of high affinity IL-2R, whereas IL-4 prohibits such action of IL-5 to prepare CL-3 cells responsive to IL-2. Here we have found that genes for p75kDa-IL-2R and p55kDa-IL-2R are differentially regulated by IL-4 and IL-5. Nonstimulated CL-3 cells constitutively express mRNA for p75kDa-IL-2R and p55kDa-IL-2R. IL-5 stimulation principally augments the expression of p75kDa-IL-2R mRNA (4- to 8-fold), although modestly increasing the expression of p55kDa-IL-2R mRNA. Kinetic studies have revealed a maximal increase in p75kDa-IL-2R mRNA expression at 12 h and a decline thereafter, substantiating our previous kinetic study of the expression of high affinity IL-2R after the IL-5 stimulation. By contrast, IL-4 stimulation modestly increases the expression of p75kDa-IL-2R mRNA, whereas markedly reducing the expression of p55kDa-IL-2R mRNA, irrespective of whether CL-3 cells were stimulated with IL-4 alone or together with IL-5 and IL-2. Moreover, addition of IL-4 into the culture containing IL-5 and IL-2 causes striking reduction in the level of J-chain mRNA, which otherwise is markedly induced by stimulation with IL-5 and IL-2. These results clearly illustrate the differential regulation of p75kDa- and p55kDa-IL-2R-gene expression by IL-5 and IL-4, and reinforce our notion that increased expression of high affinity IL-2R induced by IL-5 is responsible for the IL-2 competent state, and decreased expression of p55kDa-IL-2R by IL-4 is responsible for IL-2 unresponsive state.

Lymphokine-regulated differential expression of mRNA for p75kDa-IL-2R and p55kDa-IL-2R in a cloned B lymphoma line (BLC1-CL-3 cells)

IL-5 renders BCL1-CL-3 (CL-3) cells responsive to IL-2 by increasing the number of high affinity IL-2R, whereas IL-4 prohibits such action of IL-5 to prepare CL-3 cells responsive to IL-2. Here we have found that genes for p75kDa-IL-2R and p55kDa-IL-2R are differentially regulated by IL-4 and IL-5. Nonstimulated CL-3 cells constitutively express mRNA for p75kDa-IL-2R and p55kDa-IL-2R. IL-5 stimulation principally augments the expression of p75kDa-IL-2R mRNA (4- to 8-fold), although modestly increasing the expression of p55kDa-IL-2R mRNA. Kinetic studies have revealed a maximal increase in p75kDa-IL-2R mRNA expression at 12 h and a decline thereafter, substantiating our previous kinetic study of the expression of high affinity IL-2R after the IL-5 stimulation. By contrast, IL-4 stimulation modestly increases the expression of p75kDa-IL-2R mRNA, whereas markedly reducing the expression of p55kDa-IL-2R mRNA, irrespective of whether CL-3 cells were stimulated with IL-4 alone or together with IL-5 and IL-2. Moreover, addition of IL-4 into the culture containing IL-5 and IL-2 causes striking reduction in the level of J-chain mRNA, which otherwise is markedly induced by stimulation with IL-5 and IL-2. These results clearly illustrate the differential regulation of p75kDa- and p55kDa-IL-2R-gene expression by IL-5 and IL-4, and reinforce our notion that increased expression of high affinity IL-2R induced by IL-5 is responsible for the IL-2 competent state, and decreased expression of p55kDa-IL-2R by IL-4 is responsible for IL-2 unresponsive state.

IL-5 up-regulates but IL-4 down-regulates IL-2R expression on a cloned B lymphoma line

Both IL-4 and IL-5 demonstrate B cell growth activity. IL-5 can render a cloned neoplastic B cell line, BCL1-CL-3 cells, responsive to IL-2, whereas IL-4 has no such activity. The response to IL-5 and IL-2 proceeds in two phases: the first phase which clearly depends upon IL-5 is the obvious increase in number of high affinity IL-2R (3.1-fold) with modest increase of low affinity IL-2R (1.2-fold) and gain of the ability of facilitated IL-2-binding and internalization of IL-2, and the second phase which is induced by IL-2 in the IL-5-stimulated CL-3 cells comprises the striking increase of low affinity IL-2R (8.5-fold). Kinetic study has revealed that high affinity IL-2R expressed on CL-3 cells begins to increase at 6 h and reaches to maximum at 12 h after stimulation with IL-5 or IL-5 plus IL-2, whereas low affinity IL-2R expression increases at 18 h and becomes maximal at 24 h after stimulation of CL-3 cells with IL-5 and IL-2. However, in the presence of IL-4, IL-5 cannot induce an increase in number of high affinity IL-2R on CL-3 cells. Thus, CL-3 cells stimulated with the mixture of IL-5 and IL-4 cannot respond to IL-2, and fail to show up-regulated expression of low affinity IL-2R. IL-4 also has a capacity to modestly interfere with the action of IL-2 to up-regulate low affinity IL-2R expression on IL-5-pretreated CL-3 cells. Thus, this monoclonal B cell system provides an excellent model system to define the roles of IL-5 and IL-4 involved in the B cell differentiation and to characterize the properties of B cells competent to IL-2 stimulation and the signal transduction mechanism which operates through IL-2/IL-2R system.

IL-5 up-regulates but IL-4 down-regulates IL-2R expression on a cloned B lymphoma line

Both IL-4 and IL-5 demonstrate B cell growth activity. IL-5 can render a cloned neoplastic B cell line, BCL1-CL-3 cells, responsive to IL-2, whereas IL-4 has no such activity. The response to IL-5 and IL-2 proceeds in two phases: the first phase which clearly depends upon IL-5 is the obvious increase in number of high affinity IL-2R (3.1-fold) with modest increase of low affinity IL-2R (1.2-fold) and gain of the ability of facilitated IL-2-binding and internalization of IL-2, and the second phase which is induced by IL-2 in the IL-5-stimulated CL-3 cells comprises the striking increase of low affinity IL-2R (8.5-fold). Kinetic study has revealed that high affinity IL-2R expressed on CL-3 cells begins to increase at 6 h and reaches to maximum at 12 h after stimulation with IL-5 or IL-5 plus IL-2, whereas low affinity IL-2R expression increases at 18 h and becomes maximal at 24 h after stimulation of CL-3 cells with IL-5 and IL-2. However, in the presence of IL-4, IL-5 cannot induce an increase in number of high affinity IL-2R on CL-3 cells. Thus, CL-3 cells stimulated with the mixture of IL-5 and IL-4 cannot respond to IL-2, and fail to show up-regulated expression of low affinity IL-2R. IL-4 also has a capacity to modestly interfere with the action of IL-2 to up-regulate low affinity IL-2R expression on IL-5-pretreated CL-3 cells. Thus, this monoclonal B cell system provides an excellent model system to define the roles of IL-5 and IL-4 involved in the B cell differentiation and to characterize the properties of B cells competent to IL-2 stimulation and the signal transduction mechanism which operates through IL-2/IL-2R system.

Both B151-T cell replacing factor 1 and IL-5 regulate Ig secretion and IL-2 receptor expression on a cloned B lymphoma line

In the present study, we have demonstrated that both B151-T cell-replacing factor 1 and rIL-5 are responsible for the activity to partially induce CL-3 cells into IgM-synthesizing cells and also to synergize with IL-2 to augment IL-2R expression on and IgM synthesis in CL-3 cells. These actions of rIL-5 on a homogeneous cloned line (BCL1-CL-3 cells) allow us to identify and characterize the two alternated B cell developmental pathways. One is an IL-2-independent, IL-5-driven differentiation pathway without preceding up-regulated IL-2R expression, and the other is an IL-5 plus IL-2-dependent augmented differentiation pathway with preceding up-regulated IL-2R expression. We have also demonstrated the functional difference of two distinct B cell growth-promoting factors, B cell-stimulating factor 1 (rIL-4) and rIL-5. CL-3 cells are equally stimulated to grow by rIL-4 and rIL-5, whereas only rIL-5 can render CL-3 cells responsive to rIL-2, indicating that these two lymphokines affect B cells in a strikingly different manner.

Both B151-T cell replacing factor 1 and IL-5 regulate Ig secretion and IL-2 receptor expression on a cloned B lymphoma line

In the present study, we have demonstrated that both B151-T cell-replacing factor 1 and rIL-5 are responsible for the activity to partially induce CL-3 cells into IgM-synthesizing cells and also to synergize with IL-2 to augment IL-2R expression on and IgM synthesis in CL-3 cells. These actions of rIL-5 on a homogeneous cloned line (BCL1-CL-3 cells) allow us to identify and characterize the two alternated B cell developmental pathways. One is an IL-2-independent, IL-5-driven differentiation pathway without preceding up-regulated IL-2R expression, and the other is an IL-5 plus IL-2-dependent augmented differentiation pathway with preceding up-regulated IL-2R expression. We have also demonstrated the functional difference of two distinct B cell growth-promoting factors, B cell-stimulating factor 1 (rIL-4) and rIL-5. CL-3 cells are equally stimulated to grow by rIL-4 and rIL-5, whereas only rIL-5 can render CL-3 cells responsive to rIL-2, indicating that these two lymphokines affect B cells in a strikingly different manner.

Demonstration of up-regulated IL 2 receptor expression on an in vitro cloned BCL1 subline

We have established BCL1 CL-3 cells capable of responding to B15-TRF and interleukin 2 (IL 2). This clone has both high affinity and low affinity receptors for IL 2 (IL 2R), but IL 2 by itself did not stimulate either proliferation or immunoglobulin (Ig) secretion. B15-TRF, which possesses both growth and differentiation activity, causes an increase in size of CL-3 cells and renders CL-3 cells responsive to IL 2, including an increased expression of IL 2R (eight-fold to 10-fold) and the differentiation of CL-3 cells into Ig secretion (60 to 80% of cultured cells). CL-3 cells pretreated with B15-TRF for 12 hr become competent to respond to IL 2 by up-regulation of IL 2R within 12 hr. In contrast CL-3 cells pretreated with IL 2 for 12 hr required 24 hr B15-TRF stimulation to result in IL 2R up-regulation. Thus the ordered action of B15-TRF and IL 2 is the most effective operational pathway for the up-regulation of IL 2R. This IL 2-mediated IL 2R up-regulation and induction of Ig synthesis depends upon the concentration of IL 2 in the culture. Both responses seem to be caused by IL 2 molecules bound to high affinity IL 2R. However, the possibility of involvement of low affinity IL 2R can not be vigorously excluded. In fact the level of IL 2 required for a response is far higher than that needed for activated T cell proliferation. This cloned BCL1 subline promises to be a useful tool for studying the regulation and mechanisms of B cell responses.