Presence Of Mitogen Research Articles

Retinal properties and potential of the adult mammalian ciliary epithelium stem cells

The ciliary epithelium (CE) in the adult mammalian eye harbors a mitotic quiescent population of neural stem cells. Here we have compared the cellular and molecular properties of CE stem cells and populations of retinal progenitors that define the early and late stages of histogenesis. The CE stem cells and retinal progenitors proliferate in the presence of mitogens and share the expression of universal neural and retinal progenitor markers. However, the expression of the majority of retinal progenitor markers (e.g., Chx10) is transient in the former when compared to the latter, in vitro. They are similar to early than late retinal progenitors in their proliferative response to FGF2 and/or EGF. Analysis of the differentiation potential of CE stem cells shows that they are capable of generating both early (e.g., retinal ganglion cells) and late (e.g., rod photoreceptors) born retinal neurons. However, under identical differentiation conditions, i.e., in the presence of 1% FBS, they generate more early-born retinal neurons than late-born retinal neurons showing a preference for generating early retinal neurons. Transcription profiling of these cells and retinal progenitors demonstrate that they share ∼80% of the expressed genes. The CE stem cells have more unique genes in common with early retinal progenitors than late retinal progenitors. Both proliferative/differential potential and transcription profiles suggest that CE stem cells may be a residual population of stem cells of optic neuroepithelium, representing a stage antecedent to retinal progenitors.

TNFα‐mediated extracellular matrix remodeling is required for multiple division cycles in rat hepatocytes†

During liver regeneration, hepatocytes proliferate under the control of both proinflammatory cytokines such as tumor necrosis factor alpha (TNFalpha) and growth factors, in parallel to extracellular matrix remodeling. This study investigated mechanisms by which mitogen and extracellular matrix signals are linked for inducing proliferation of differentiated hepatocytes. The authors used adult rat hepatocytes in coculture with liver biliary cells, because cells are stably differentiated for several weeks, capable of extracellular matrix deposition, and unable to divide in response to growth factor alone. This work demonstrated that hepatocytes could undergo several proliferation waves without loss of differentiation by using alternating periods of TNFalpha/growth factor stimulation and deprivation. Three days after stimulation with TNFalpha and epidermal growth factor (EGF), up to 35% of hepatocytes divided. Demonstration was also provided that EGF alone only promoted cell progression up to late G(1), whereas TNFalpha was necessary for G(1)/S transition and Cdk1 induction. TNFalpha promoted an extracellular matrix (ECM) degradation that involved the matrix metalloproteinase MMP-9 induction through activation of NF-kappaB pathway. Finally, the authors showed that ECM remodeling signal was required for initiating any new hepatocyte division wave, in presence of mitogen. In conclusion, these results highlight that hepatocyte division is dependent on ECM deposition associated with differentiation status, and that ECM degradation signal is critical in controlling G(1)/S transition and Cdk1 induction. These results provide new insights for understanding the unique hepatocyte proliferation control and improving regeneration in patients suffering from liver damage.

Characteristics of human neural stem cells In Vitro and after transplantation into rat brain

We studied the effect of culturing conditions on the fate of human neural stem cells after transplantation into rat brain. Human neural stem cells cultured in the presence of mitogens without LIF migrated along the ependyma and cerebral vessels of recipients, but to a great extent degenerated by the 20th day after transplantation. Neural stem cells cultured with LIF migrated, apart from the above mentioned pathways, in the cortex and hippocampus, well survived; proliferating cells were retained 30 days after transplantation.

Autologous transplantation of expanded neural precursor cells into the demyelinated monkey spinal cord

The objective of this study was to establish if neural precursor cells could safely be developed from biopsy of the subventricular zone (SVZ) in the non-human primate (marmoset), and to determine their myelinating potential after autologous transplantation into a demyelinated lesion. Small amounts of tissue were safely collected from the subventricular–subependymal zone of the adult primate brain under ultrasonography without any neurological deficit. Neural precursor cells were isolated and expanded in the presence of mitogen in vitro. The dorsal columns of the adult marmoset spinal cord were demyelinated by X-irradiation and intraspinal injections of ethidium bromide in the center of the radiation field. Cell suspensions of the neural precursors were microinjected through a micropipette into the demyelinated lesion site in the spinal cord. Lesions were histologically examined 3 weeks after transplantation. Light and electron microscopic examination of plastic embedded sections revealed a significant number of myelinating profiles in the transplantation zone; no myelination was observed in control lesions. The myelinated axons had predominantly peripheral patterns of myelination. These results demonstrate that autologous transplantation of neural precursor cells in the adult nonhuman primate can remyelinate demyelinated central nervous system (CNS) axons, thus suggesting the potential utility of such an approach in demyelinating lesions in humans.

Optimum culture conditions for specific and nonspecific activation of whole blood and PBMC for intracellular cytokine assessment by flow cytometry

The assessment of cytokine production is an important component of studies of cell-mediated immune responses (CMI) to immunological challenges. In this study, we present a method to enhance the detection of cytokine-producing cells by allowing antigen-specific cells to expand in long-term culture. We investigated the influence of the degree of dilution of whole blood and the duration of the incubation period on whole blood as well as peripheral blood mononuclear cells (PBMCs), cultured in the absence or presence of mitogens, superantigens or specific antigens, for intracellular cytokine production (IFNγ, TNFα, IL-2, IL-4, IL-10 and IL-13) by CD4 + and CD8 + T lymphocytes using four-colour flow cytometry. Whole blood was diluted 1/1, 1/2, 1/5 and 1/10, and cultured for 6, 24, 48, 72 and 120 h in the presence of antibodies against the co-stimulatory molecules CD28 and CD49d, and, during the last 4 h of culture, in the presence of brefeldin A. Optimum conditions for detection of a high number of IFNγ-positive cells were observed after 72 h of culture in blood diluted 1/10. Median frequencies of IFNγ + cells obtained after activation by PMA-ionomycin, PHA or SEA-B were 29.3%, 20.0% and 6.8% for CD4 + cells, and 67.8%, 20.6% and 6.8% for CD8 + cells. In blood samples diluted 1/5 or 1/10, and cultured in the presence of cytomegalovirus (CMV) or varicella-zoster virus (VZV), mean peak levels of 2.8% and 1.4% IFNγ +CD4 + cells were recorded at 120 h. The levels of cells producing cytokines other than IFNγ were generally much lower and, in the case of IL-4 and IL-13, difficult to distinguish from background levels recorded in cultures with medium only. Kinetic studies of cytokine production by PBMCs showed a pattern similar to that of whole blood with peak levels of IFNγ-producing cells recorded at 72 h. The increased levels of IFNγ production after culture for 72 h were due to an expansion of the numbers of cytokine-producing cells responsive to a specific stimulus. Antigen-specific cells are usually present only at low levels in peripheral blood and may not be detected following simple activation for a few hours. To reach a level of detection in such cases, culture of diluted blood for several days is recommended.

Modern management of children with haemophagocytic lymphohistiocytosis.

Modern management of children with haemophagocytic lymphohistiocytosis.

Myelin transcription factor 1 (Myt1) modulates the proliferation and differentiation of oligodendrocyte lineage cells

Myelin transcription factor 1 (Myt1) is a zinc finger DNA-binding protein that is expressed in neural progenitors and oligodendrocyte lineage cells. This study examines the role of Myt1 in oligodendrocyte lineage cells by overexpressing putative functional domains, a four-zinc finger DNA-binding region (4FMyt1) or a central protein–protein interaction domain (CDMyt1), without the predicted transcriptional activation domain. In the presence of mitogens, overexpression of 4FMyt1 inhibited proliferation of oligodendrocyte progenitors, but not cell types (astrocytes and NIH3T3 cells) lacking endogenous Myt1. Expression of 4FMyt1 inhibited the differentiation of oligodendrocyte progenitors into oligodendrocytes as assessed by morphology, immunostaining, and myelin gene expression. Progenitor differentiation was similarly inhibited by expression of CDMyt1 but only partially suppressed by overexpression of the intact Myt1. These data indicate that Myt1 may regulate a critical transition point in oligodendrocyte lineage development by modulating oligodendrocyte progenitor proliferation relative to terminal differentiation and up-regulation of myelin gene transcription.

Glutamate transporter expression and function in human glial progenitors.

Glutamate is the major neurotransmitter of the brain, whose extracellular levels are tightly controlled by glutamate transporters. Five glutamate transporters in the human brain (EAAT1-5) are present on both astroglia and neurons. We characterize the profile of three different human astroglial progenitors in vitro: human glial restricted precursors (HGRP), human astrocyte precursors (HAPC), and early-differentiated astrocytes. EAAT 1, EAAT3, and EAAT4 are all expressed in GRPs with a subsequent upregulation of EAAT1 following differentiation of GRPs into GRP-derived astrocytes in the presence of bone morphogenic protein (BMP-4). This corresponds to a significant increase in the glutamate transport capacity of these cells. EAAT2, the transporter responsible for the bulk of glutamate transport in the adult brain, is not expressed as a full-length protein, nor does it appear to have functional significance (as determined by the EAAT2 inhibitor dihydrokainate) in these precursors. A splice variant of EAAT2, termed EAAT2b, does appear to be present in low levels, however. EAAT3 and EAAT4 expression is reduced as glial maturation progresses both in astrocyte precursors and early-differentiated astrocytes and is consistent with their role in adult tissues as primarily neuronal glutamate transporters. These human glial precursors offer several advantages as tools for understanding glial biology because they can be passaged extensively in the presence of mitogens, afford the potential to study the temporal changes in glutamate transporter expression in a tightly controlled fashion, and are cultured in the absence of neuronal coculture, allowing for the independent study of astroglial biology.

Immunomodulatory activities of Clausena excavata Burm. f. wood extracts

In vitro immunomodulatory activities of aqueous extract, acetone extract and the Thai folklore extract of Clausena excavata Burm. f. on mouse immune system were investigated. The phagocytic activity of macrophages and splenocyte proliferation in the absence and presence of mitogens (lipopolysaccharide, LPS) or pokeweed mitogen, PWM) were assayed. The aqueous extract exhibited the maximum effect on both respiratory burst response and lysosomal enzyme activity more than the acetone extract and the Thai folklore extract indicating effective phagocytic activation. For splenocyte proliferation assay, the Thai folklore extract with LPS gave the maximum activity higher than that with PWM, suggesting specificity towards B cell proliferation through T cell independent pathway the same as LPS. The present study revealed the immumunomodulating activity, which could be explained the traditional use of this plant in Thailand.

Upregulation of class II histone deacetylases mRNA during neural differentiation of cultured rat hippocampal progenitor cells

We studied the expression of histone deacetylases (HDACs 1–10) mRNAs during early differentiation of cultured rat hippocampal progenitor cells using Northern blot analysis. Embryonic rat hippocampal progenitors were kept proliferating and undifferentiated (neurospheres) in the presence of mitogens and induced to stop proliferation and to differentiate into neurons and astrocytes by mitogen removal. We found two- to four-fold elevated levels of mRNAs for HDAC 5, 6, 7 and 9 in early differentiation times in comparison with proliferating neurospheres while mRNA levels for HDAC 1, 2 and 3 did not change significantly. Interestingly, the upregulated HDACs all belong to class II of histone deacetylases. mRNAs for HDAC 4, 8 and 10 were not detectable by Northern analysis. We suggest that the changes in HDAC mRNA expression levels might be connected with chromatin rearrangement during neural differentiation.

Neural stem cells: plasticity and therapeutic potential

The adult brain retains neural stem cells (NSC). At least two evidences support this notion; firstly primary precursors within the central nervous system (CNS) germinal zone continue to produce neuron and glia throughout an animal life; second, cells from adult brain with the properties of NCS can be grown in vitro in presence of mitogens. NSCs are multipotential precursors that grow and self‐renew in culture in response to growth factors for extensive time. It has recently been argued that NSCs undergo rapid transformation in vitro. Our recent data, which describe the systematic investigation of the functional properties of NSCs upon long‐term culturing shown that NSCs do not display any sign of transformations neither at early nor at late culture stages; moreover the self‐renewal capacity of NSCs does not change over time. I will then show how we can confirm previous findings showing how NSCs do possess the ability to give rise to non‐neural‐derivatives, i.e. mesodermal cells. Finally, I will illustrate the lack of any tumorigenic potential of NSCs and their striking capacity for engraftment in the CNS.

Neural stem and progenitor cells of human embryos and fetuses as a basis of biomedical new technologies

Isolation and cultivation of stem and progenitor cells of human embryos and fetuses at the age of 7-12 weeks of gestation have been described. The embryonic cells of human brain formed neurospheres with heterogenous composition. Cell differentiation took place not only in the presence of serum or as a result of attachment of neurosphere to a sublayer, but also in floating neurospheres in the presence of mitogens. In most neurospheres, the nestin-immunopositive cells were located near the surface while the cells stained for beta-tubulin III and glial fibrillar acid protein, as compact groups inside the neurospheres.

Histone Deacetylase Activity Is Necessary for Oligodendrocyte Lineage Progression

Gene expression can be modulated by chromatin changes induced by histone acetylation and deacetylation. Acetylation of histone lysine residues by acetyltransferases is associated with transcriptionally active chromatin, whereas the removal of acetyl groups by histone deacetylases (HDACs) correlates with repressed chromatin. Recent evidence has shown that histone deacetylation is responsible for restricting neuronal gene expression, whereas histone acetylation is necessary for astrocytic differentiation We now asked whether histone acetylation or deacetylation was necessary for oligodendrocyte differentiation. Neonatal rat cortical progenitors were kept proliferating and undifferentiated in the presence of mitogens and induced to stop proliferating and differentiate into oligodendrocytes by mitogen removal. Histone deacetylation was observed during the temporal window between exit from the cell cycle and onset of differentiation, which was characterized by acquisition of branched morphology and myelin gene expression. Blocking HDAC activity during this critical window using the inhibitor trichostatin A (TSA) prevented the progression of progenitors into mature oligodendrocytes. TSA-treated progenitors were able to exit from the cell cycle but did not progress to oligodendrocytes. Their development was arrested at the progenitor stage, characterized by simple morphology and lack of myelin gene expression. The effect of TSA on progenitor differentiation was lineage specific, because TSA did not affect the ability of these cells to differentiate into type II astrocytes when cultured in the presence of serum. From these data, we conclude that histone deacetylation is a necessary component of the oligodendrocyte differentiation program.

Gene therapy of RAG-2−/− mice: sustained correction of the immunodeficiency

Patients with mutations of either RAG-1 or RAG-2 genes suffer from severe combined immunodeficiency (SCID) characterized by the lack of T and B lymphocytes. The only curative treatment today consists of hematopoietic stem cell (HSC) transplantation, which is only partially successful in the absence of an HLA genoidentical donor, thus justifying research to find an alternative therapeutic approach. To this end, RAG-2-deficient mice were used to test whether retrovirally mediated ex vivo gene transfer into HSCs could provide long-term correction of the immunologic deficiency. Murine RAG-2-/-Sca-1(+) selected bone marrow cells were transduced with a modified Moloney leukemia virus (MLV)-based MND (myeloproliferative sarcoma virus enhancer, negative control region deleted, dl587rev primer-binding site substituted) retroviral vector containing the RAG-2 cDNA and transplanted into RAG-2-/- sublethally irradiated mice (3Gy). Two months later, T- and B-cell development was achieved in all mice. Diverse repertoire of T cells as well as proliferative capacity in the presence of mitogens, allogeneic cells, and keyhole limpet hemocyanin (KLH) were shown. B-cell function as shown by serum Ig levels and antibody response to a challenge by KLH also developed. Lymphoid subsets and function were shown to be stable over a one-year period without evidence of any detectable toxicity. Noteworthy, a selective advantage for transduced lymphoid cells was evidenced by comparative provirus quantification in lymphoid and myeloid lineages. Altogether, this study demonstrates the efficiency of ex vivo RAG-2 gene transfer in HSCs to correct the immune deficiency of RAG-2-/- mice, constituting a significant step toward clinical application.

Hemophagocytic lymphohistiocytosis is associated with deficiencies of cellular cytolysis but normal expression of transcripts relevant to killer-cell–induced apoptosis

In 65 patients with hemophagocytic lymphohistiocytosis (HLH), we found an as yet undescribed heterogeneity of defects in cellular cytotoxicity when assay conditions were modified by the incubation time, the presence of mitogen, or interleukin-2 (IL-2). The standard 4-hour natural killer (NK) test against K562 targets was negative in all patients. In patients deficient in type 1 (n = 21), type 2 (n = 5), and type 4 (n = 8) HLH, negative NK function could be reconstituted by mitogen, by IL-2, or by prolongation of the incubation time (16 hours), respectively. Most patients (n = 31) displayed the type 3 defect, defined by a lack of any cellular cytotoxicity independent of assay variations. The characteristic hypercytokinemia also concerned counterregulatory cytokines, such as proinflammatory interferon-gamma (IFN-gamma), simultaneously elevated with suppressive IL-10 in 38% of types 1-, 2-, and 4-deficient patients and in 71% of type 3-deficient patients. Elevated IFN-gamma alone correlated with high liver enzymes, but sCD95-ligand and sCD25 did not-though these markers were expected to indicate the extent of histiocytic organ infiltration. Outcome analysis revealed more deaths in patients with type 3 deficiency (P =.017). Molecular defects were associated with homozygously mutated perforin only in 4 patients, but other type 3 patients expressed normal transcripts of effector molecules for target-cell apoptosis, including perforin and granzyme family members, as demonstrated by RNase protection analysis. Thus, target-cell recognition or differentiation defects are likely to explain this severe phenotype in HLH. Hyperactive phagocytes combined with NK defects may imply defects on the level of the antigen-presenting cell.

Adult Corneal Limbal Epithelium: A Model for Studying Neural Potential of Non-Neural Stem Cells/Progenitors

Recent studies suggest that tissue-specific stem cells possess much wider potential for differentiation than previously thought and can, in some instances, even cross germ layer boundaries. However, information is lacking regarding the efficiency and the fidelity of their differentiation along heterologous lineages. To address these issues of transdifferentiation, we have analyzed the heterologous potential of stem cells within the same germ layer. We report the neural potential of cells isolated from the limbal epithelium of the adult cornea. Limbal epithelium, which, like the neuroepithelium, is ectodermally derived, participates in the regeneration of cornea throughout life. We have observed that limbal epithelial cells, when removed from their niche and cultured in the presence of mitogens, begin to express neural progenitor markers. Based on the self-renewal property, it is likely that the nestin-positive progenitors are derived from limbal stem cells rather than transit-amplifying (TA) cells that have limited proliferating potential. In differentiation conditions, a subset of these cells acquire neural morphology and express transcripts and proteins specific to neurons and glia, suggesting their differentiation along neural lineage. The acquisition of neural properties is regulated by BMP signaling. Neural differentiation of these cells is also observed upon heterotopic transplantation. Investigation of functional differentiation of cells by electrophysiological analysis reveals properties consistent with the presence of glia that are influenced by extracellular cues. However, similar analyses coupled with Ca 2+ imaging suggest an incomplete differentiation of limbal epithelial-derived neural progenitors into neurons in the condition studied. Our study, therefore, draws attention toward the necessity for rigorous characterization of transdifferentiation and offers a model for characterizing neural potential of heterologous stem cells/progenitors.

Adult Corneal Limbal Epithelium: A Model for Studying Neural Potential of Non-Neural Stem Cells/Progenitors

Recent studies suggest that tissue-specific stem cells possess much wider potential for differentiation than previously thought and can, in some instances, even cross germ layer boundaries. However, information is lacking regarding the efficiency and the fidelity of their differentiation along heterologous lineages. To address these issues of transdifferentiation, we have analyzed the heterologous potential of stem cells within the same germ layer. We report the neural potential of cells isolated from the limbal epithelium of the adult cornea. Limbal epithelium, which, like the neuroepithelium, is ectodermally derived, participates in the regeneration of cornea throughout life. We have observed that limbal epithelial cells, when removed from their niche and cultured in the presence of mitogens, begin to express neural progenitor markers. Based on the self-renewal property, it is likely that the nestin-positive progenitors are derived from limbal stem cells rather than transit-amplifying (TA) cells that have limited proliferating potential. In differentiation conditions, a subset of these cells acquire neural morphology and express transcripts and proteins specific to neurons and glia, suggesting their differentiation along neural lineage. The acquisition of neural properties is regulated by BMP signaling. Neural differentiation of these cells is also observed upon heterotopic transplantation. Investigation of functional differentiation of cells by electrophysiological analysis reveals properties consistent with the presence of glia that are influenced by extracellular cues. However, similar analyses coupled with Ca 2+ imaging suggest an incomplete differentiation of limbal epithelial-derived neural progenitors into neurons in the condition studied. Our study, therefore, draws attention toward the necessity for rigorous characterization of transdifferentiation and offers a model for characterizing neural potential of heterologous stem cells/progenitors.

P27 cytoplasmic localization is regulated by phosphorylation on Ser10 and is not a prerequisite for its proteolysis.

The activity of the cyclin-dependent kinase inhibitor p27 is controlled by its concentration and subcellular localization. However, the mechanisms that regulate its intracellular transport are poorly understood. Here we show that p27 is phosphorylated on Ser10 in vivo and that mutation of Ser10 to Ala inhibits p27 cytoplasmic relocalization in response to mitogenic stimulation. In contrast, a fraction of wild-type p27 and a p27(S10D)-phospho-mimetic mutant translocates to the cytoplasm in the presence of mitogens. G1 nuclear export of p27 and its Ser10 phosphorylation precede cyclin-dependent kinase 2 (Cdk2) activation and degradation of the bulk of p27. Interestingly, leptomycin B-mediated nuclear accumulation accelerates the turnover of endogenous p27; the p27(S10A) mutant, which is trapped in the nucleus, has a shorter half-life than wild-type p27 and the p27(S10D) mutant. In summary, p27 is efficiently degraded in the nucleus and phosphorylation of Ser10 is necessary for the nuclear to cytoplasmic redistribution of a fraction of p27 in response to mitogenic stimulation. This cytoplasmic localization may serve to decrease the abundance of p27 in the nucleus below a certain threshold required for activation of cyclin-Cdk2 complexes.

Mutagenicity at the Hprt locus in T cells of female mice following inhalation exposures to low levels of 1,3-butadiene

A study was conducted to test the hypothesis that repeated low level exposures to 1,3-butadiene (BD), approaching the OSHA occupational threshold for this chemical, produce a significant mutagenic response in mice. Female B6C3F1 mice (4–5 weeks of age) were exposed by inhalation for 2 weeks (6 h/day, 5 days/week) to 0 or 3 ppm BD, and then necropsied at 4 weeks after the cessation of exposures to measure the frequency of mutations (MF) at the Hprt locus using the T-lymphocyte clonal assay. At necropsy, T cells were isolated from spleen and cultured in the presence of mitogen, growth factors, and a selection agent. Cells were scored for growth on days 8–9 after plating to determine cloning efficiencies (CEs) and Hprt MFs. There was a marginal but significant reduction in the growth of splenic T cells from mice exposed to 3 ppm ( n=27) compared with control mice ( n=24) ( P=0.004), suggesting the occurrence of BD-induced cytotoxicity at this low exposure concentration. In addition, the average Hprt MF in mice exposed to 3 ppm BD [1.54±0.82 (S.D.)×10 −6] was significantly increased by 1.6-fold over the average control value of 0.96±0.51 (S.D.)×10 −6 ( P=0.004). Comparisons of these data to earlier Hprt mutagenicity studies of mice exposed to high concentrations of BD (where significant mutagenic but not cytotoxic effects were observed) indicate that the ability to detect the cytotoxic and mutagenic responses of T cells to low levels of BD was enhanced by using a much larger sample size than usual for both the control and treatment groups. Additional analyses of the quantitative relationships between CE and MF demonstrated that CE had no significant effect upon MF values in sham-exposed control mice or mice exposed to low-level BD. Furthermore, the approaches for assessing the impact of CE and clonality on Hprt MFs in these control and BD-exposed mice were applied with the same rigor as in in vivo Hprt mutagenicity studies in human children. The overall study results support the conclusion that short-term low-level BD exposure is mutagenic in the mouse.

Characterization of the in vitro and in vivo activity of monoclonal antibodies to human IL-18.

IL-18 is a cytokine with potent IFN-gamma inducing activities as well as an important mediator of Th1 polarized immune responses. In this study we demonstrated that IL-18 induces the concentration-dependent production of the proinflammatory mediators IFN-gamma, IL-6, and GM-CSF, but not the anti-inflammatory cytokine, IL-10 from peripheral blood lymphocytes in the presence of mitogen. Three neutralizing IL-18 monoclonal antibodies (MAbs) were investigated, one of which (2C10) inhibited IL-18 bioactivity with an IC50 of 0.1 nM and had a K(D) of 3.9 x 10(-11) M. A NOD/SCID mouse model engrafted with human peripheral blood lymphocytes was developed to test the in vivo efficacy of this MAb. The IFN-gamma production induced by LPS administration was inhibited approximately 90% by prior dosing of MAb 2C10. The therapeutic utility of a high-affinity IL-18 MAb may be of benefit in Th1-driven autoimmune diseases such as rheumatoid arthritis and Crohn's Disease, where elevated levels of IL-18 have been observed.