Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

Cancer Relevance of Circulating Antibodies Against LINE-1 Antigens in Humans

Long interspersed nuclear element-1 (LINE-1 or L1), the most abundant family of autonomous retrotransposons occupying over 17% of human DNA, is epigenetically silenced in normal tissues by the mechanisms involving p53 but is frequently derepressed in cancer, suggesting that L1-encoded proteins may act as tumor-associated antigens recognized by the immune system. In this study, we established an immunoassay to detect circulating autoantibodies against L1 proteins in human blood. Using this assay in >2,800 individuals with or without cancer, we observed significantly higher IgG titers against L1-encoded ORF1p and ORF2p in patients with lung, pancreatic, ovarian, esophageal, and liver cancers than in healthy individuals. Remarkably, elevated levels of anti-ORF1p-reactive IgG were observed in patients with cancer with disease stages 1 and 2, indicating that the immune response to L1 antigens can occur in the early phases of carcinogenesis. We concluded that the antibody response against L1 antigens could contribute to the diagnosis and determination of immunoreactivity of tumors among cancer types that frequently escape early detection.

SIGNIFICANCE

The discovery of autoantibodies against antigens encoded by L1 retrotransposons in patients with five poorly curable cancer types has potential implications for the detection of an ongoing carcinogenic process and tumor immunoreactivity.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Immune checkpoint protein VSIG4 as a biomarker of aging in murine adipose tissue

Adipose tissue is recognized as a major source of systemic inflammation with age, driving age-related tissue dysfunction and pathogenesis. Macrophages (Mφ) are central to these changes yet adipose tissue Mφ (ATMs) from aged mice remain poorly characterized. To identify biomarkers underlying changes in aged adipose tissue, we performed an unbiased RNA-seq analysis of ATMs from young (8-week-old) and healthy aged (80-week-old) mice. One of the genes identified, V-set immunoglobulin-domain-containing 4 (VSIG4/CRIg), encodes a Mφ-associated complement receptor and B7 family-related immune checkpoint protein. Here, we demonstrate that Vsig4 expression is highly upregulated with age in perigonadal white adipose tissue (gWAT) in two mouse strains (inbred C57BL/6J and outbred NIH Swiss) independent of gender. The accumulation of VSIG4 was mainly attributed to a fourfold increase in the proportion of VSIG4+ ATMs (13%-52%). In a longitudinal study, VSIG4 expression in gWAT showed a strong correlation with age within a cohort of male and female mice and correlated strongly with physiological frailty index (PFI, a multi-parameter assessment of health) in male mice. Our results indicate that VSIG4 is a novel biomarker of aged murine ATMs. VSIG4 expression was also found to be elevated in other aging tissues (e.g., thymus) and was strongly induced in tumor-adjacent stroma in cases of spontaneous and xenograft lung cancer models. VSIG4 expression was recently associated with cancer and several inflammatory diseases with diagnostic and prognostic potential in both mice and humans. Further investigation is required to determine whether VSIG4-positive Mφ contribute to immunosenescence and/or systemic age-related deficits.

p16(Ink4a) and senescence-associated β-galactosidase can be induced in macrophages as part of a reversible response to physiological stimuli

Constitutive p16^Ink4a expression, along with senescence-associated β-galactosidase (SAβG), are commonly accepted biomarkers of senescent cells (SCs). Recent reports attributed improvement of the healthspan of aged mice following p16^Ink4a-positive cell killing to the eradication of accumulated SCs. However, detection of p16^Ink4a/SAβG-positive macrophages in the adipose tissue of old mice and in the peritoneal cavity of young animals following injection of alginate-encapsulated SCs has raised concerns about the exclusivity of these markers for SCs. Here we report that expression of p16^Ink4a and SAβG in macrophages is acquired as part of a physiological response to immune stimuli rather than through senescence, consistent with reports that p16^Ink4a plays a role in macrophage polarization and response. Unlike SCs, p16^Ink4a/SAβG-positive macrophages can be induced in p53-null mice. Macrophages, but not mesenchymal SCs, lose both markers in response to M1- [LPS, IFN-α, Poly(I:C)] and increase their expression in response to M2-inducing stimuli (IL-4, IL-13). Moreover, interferon-inducing agent Poly(I:C) dramatically reduced p16^Ink4a expression in vivo in our alginate bead model and in the adipose tissue of aged mice. These observations suggest that the antiaging effects following eradication of p16^Ink4a-positive cells may not be solely attributed to SCs but also to non-senescent p16^Ink4a/SAβG-positive macrophages.

Aging of mice is associated with p16(Ink4a)- and β-galactosidase-positive macrophage accumulation that can be induced in young mice by senescent cells

Senescent cells (SCs) have been considered a source of age-related chronic sterile systemic inflammation and a target for anti-aging therapies. To understand mechanisms controlling the amount of SCs, we analyzed the phenomenon of rapid clearance of human senescent fibroblasts implanted into SCID mice, which can be overcome when SCs were embedded into alginate beads preventing them from immunocyte attack. To identify putative SC killers, we analyzed the content of cell populations in lavage and capsules formed around the SC-containing beads. One of the major cell types attracted by secretory factors of SCs was a subpopulation of macrophages characterized by p16(Ink4a) gene expression and β-galactosidase activity at pH6.0 (β-gal(pH6)), thus resembling SCs. Consistently, mice with p16(Ink4a) promoter-driven luciferase, developed bright luminescence of their peritoneal cavity within two weeks following implantation of SCs embedded in alginate beads. p16(Ink4a)/β-gal(pH6)-expressing cells had surface biomarkers of macrophages F4/80 and were sensitive to liposomal clodronate used for the selective killing of cells capable of phagocytosis. At the same time, clodronate failed to kill bona fide SCs generated in vitro by genotoxic stress. Old mice with elevated proportion of p16(Ink4a)/β-gal(pH6)-positive cells in their tissues demonstrated reduction of both following systemic clodronate treatment, indicating that a significant proportion of cells previously considered to be SCs are actually a subclass of macrophages. These observations point at a significant role of p16(Ink4a)/β-gal(pH6)-positive macrophages in aging, which previously was attributed solely to SCs. They require re-interpretation of the mechanisms underlying rejuvenating effects following eradication of p16(Ink4a)/β-gal(pH6)-positive cells and reconsideration of potential cellular target for anti-aging treatment.

Protective effects of transgenic human endothelial protein C receptor expression in murine models of transplantation

Thrombosis and inflammation are major obstacles to successful pig-to-human solid organ xenotransplantation. A potential solution is genetic modification of the donor pig to overexpress molecules such as the endothelial protein C receptor (EPCR), which has anticoagulant, anti-inflammatory and cytoprotective signaling properties. Transgenic mice expressing human EPCR (hEPCR) were generated and characterized to test this approach. hEPCR was expressed widely and its compatibility with the mouse protein C pathway was evident from the anticoagulant phenotype of the transgenic mice, which exhibited a prolonged tail bleeding time and resistance to collagen-induced thrombosis. hEPCR mice were protected in a model of warm renal ischemia reperfusion injury compared to wild type (WT) littermates (mean serum creatinine 39.0 ± 2.3 μmol/L vs. 78.5 ± 10.0 μmol/L, p < 0.05; mean injury score 31 ± 7% vs. 56 ± 5%, p < 0.05). Heterotopic cardiac xenografts from hEPCR mice showed a small but significant prolongation of survival in C6-deficient PVG rat recipients compared to WT grafts (median graft survival 6 vs. 5 days, p < 0.05), with less hemorrhage and edema in rejected transgenic grafts. These data indicate that it is possible to overexpress EPCR at a sufficient level to provide protection against transplant-related thrombotic and inflammatory injury, without detrimental effects in the donor animal.

Distinct functions of evolutionary conserved MSF1 and late embryogenesis abundant (LEA)-like domains in mitochondria

PRELID1, the only late embryogenesis abundant (LEA) domain-containing protein in humans, exerts cytoprotective effects through its LEA domain within the mitochondria. Although PRELID1 homologs in vertebrates contain the LEA domain, homologs in lower eukaryotes are thought to lack this domain. In this study, we identify a novel LEA-like domain in a yeast PRELID1 homolog, Ups2p, which contains sequence conservation with the LEA domain of human PRELID1. PRELID1 homologs, including Ups2p, are known to contain the PRELI/MSF1 domain. Our study reveals that the MSF1 domain of Ups2p maintains proper mitochondrial electron transport chain function, respiratory competency, and mitochondrial phosphatidylethanolamine metabolism. The Ups2p MSF1 domain mediates cardiolipin depletion in the absence of Ups1p. However, the Ups2p LEA-like domain is responsible for cardiolipin depletion resulting from UPS2 overexpression. The regulation of phosphatidylethanolamine levels by the MSF1 domain is antagonized by the Ups2p LEA-like domain. We demonstrate that the yeast LEA-like domain protects cells from oxidative stress and can be functionally replaced by the human LEA domain. Together our studies suggest distinct roles of MSF1 and LEA-like domains in mitochondrial function and resistance to oxidative stress.

Interleukin-6 induces an epithelial-mesenchymal transition phenotype in human breast cancer cells

Breast tumor interleukin-6 (IL-6) levels increase with tumor grade, and elevated serum IL-6 correlates with poor breast cancer patient survival. Epithelial-mesenchymal transition (EMT) phenotypes such as impaired E-cadherin expression or aberrant Vimentin induction are associated with enhanced metastasis and unfavorable clinical outcome in breast cancer. Despite this fact, few tumor microenvironment-derived extracellular signaling factors capable of provoking such a phenotypic transition have been identified. In this study, we showed that IL-6 promoted E-cadherin repression among a panel of estrogen receptor-alpha-positive human breast cancer cells. Furthermore, ectopic stable IL-6 expressing MCF-7 breast adenocarcinoma cells (MCF-7(IL-6)) exhibited an EMT phenotype characterized by impaired E-cadherin expression and induction of Vimentin, N-cadherin, Snail and Twist. MCF-7(IL-6) cells formed xenograft tumors that displayed loss of E-cadherin, robust Vimentin induction, increased proliferative indices, advanced tumor grade and undifferentiated histology. Finally, we showed aberrant IL-6 production and STAT3 activation in MCF-7 cells that constitutively express Twist, a metastatic regulator and direct transcriptional repressor of E-cadherin. To our knowledge, this is the first study that shows IL-6 as an inducer of an EMT phenotype in breast cancer cells and implicates its potential to promote breast cancer metastasis.

Fluctuation analysis CalculatOR: a web tool for the determination of mutation rate using Luria-Delbruck fluctuation analysis

SUMMARY

The program Fluctuation AnaLysis CalculatOR (FALCOR) is a web tool designed for use with Luria-Delbrück fluctuation analysis to calculate the frequency and rate from various mutation assays in bacteria and yeast. Three calculation methods are available through this program: (i) Ma-Sandri-Sarkar Maximum Likelihood Estimator (MSS-MLE) method, (ii) Lea-Coulson method of the median (LC) and (iii) frequency.

AVAILABILITY

The FALCOR rate calculator is currently accessible at http://www.mitochondria.org/protocols/FALCOR.html. This program is written as a Java Applet, requiring a web browser enabled with Sun MicroSystems' Java Virtual Machine.

Stat3 activation in human endometrial and cervical cancers

The activation of signal transducer and activator of transcription 3 (Stat3) has been implicated in the oncogenesis of cancer and is regarded as a novel target for cancer therapy. Stat3 is classified as a proto-oncogene, because an activated form of Stat3 can mediate oncogenic transformation in cultured cells and tumour formation in nude mice. The constitutive activation of Stat3 has been frequently detected in various types of human cancers. However, the constitutive activation of Stat3 in endometrial and cervical cancers has not been studied. We examined tyrosine phosphorylation of Stat3 (activated form of Stat3) in multiple endometrial and cervical cancer tissues using tissue microarray slides as well as cancer cell lines to explore the possible activation of Stat3. Our results indicated that elevated phosphorylation of Stat3 was detected in cervical and endometrial cancer cell lines. Our results also showed that elevated levels of phosphorylation of Stat3 protein were detected in the endometrial and cervical cancer specimens. This is the first study to demonstrate that Stat3 is activated in human endometrial and cervical cancer tissues. Immunohistochemical staining showed that activated Stat3 is associated with increased expression of downstream antiapoptotic genes, Bcl-xL, survivin, and Mcl-1 in these tissues. Expression of a dominant-negative Stat3 mutant using adenovirus-mediated gene transfer inhibited cell growth and induced apoptosis in HeLa and SiHa cervical cancer cell lines expressing elevated levels of Stat3 phosphorylation. Further, a JAK/Stat3 small molecular inhibitor, JSI-124, induced apoptosis more selectively in HeLa and SiHa cancer cell lines than Ishikawa cell line without elevated levels of Stat3 phosphorylation. These results indicate that Stat3 is activated in human endometrial and cervical cancers and the inhibition of constitutive Stat3 signaling may be an effective target for cancer intervention in these two cancers.

Glucocorticoids of bison bulls in relation to social status

A primary response to stress is an increase in circulating adrenal glucocorticoids (GC) such as cortisol. Two hypotheses propose differential stress responses to agonistic and aggressive interactions in social groups. If subordinate animals are subjected to social and psychological stressors leading to chronic GC elevation, the 'stress of subordination' hypothesis predicts that GCs will be higher in subordinates than dominants. Alternatively, if dominant animals are subject to physiological stressors (e.g., fight at higher rates than subordinates) or hierarchies are unstable, the 'stress of domination' hypothesis predicts higher GCs in dominant individuals. Both models predict that GC levels will peak during the breeding season. We tested these predictions in bison bulls (Bison bison) using fecal steroid analysis to characterize GC concentration and behavioral observations to determine dominance rank, copulatory success, and tending status of bulls. Fecal samples were collected during 2003 from adult bison bulls during pre-rut (June), rut (July-August), and post-rut (September). Matched sample data indicated that mean GC levels (ng/g feces) of bulls strongly peaked during the 4-week rut, doubling from pre-rut to rut and then declining again during post-rut. High ranked dominant bulls maintained higher GC levels than lower ranked subordinate bulls. Dominance rank was positively correlated with copulatory success and age, and dominant bulls were more likely to tend (guard) cows as they approached estrus. There was a positive correlation between GC level and copulatory success, with prime-aged bulls (> or =7 years) obtaining the most copulations. GC levels were positively correlated with bull androgen levels determined in a previous study. These results support the 'stress of domination' hypothesis, indicating that dominant bison bulls pay a significant physiological price for high social status and the opportunity to mate.

Survivin-directed RNA interference cocktail is a potent suppressor of tumour growth in vivo

BACKGROUND

Survivin is proposed to play a central role in the progression and resistance to therapy of diverse tumour types. High levels of this molecule in tumour cells also correlate with loss of the TP53 tumour suppressor gene, suggesting a molecular connection between TP53 loss and transcriptional induction of Survivin. Patients with TP53 germline mutations, such as those with Li-Fraumeni syndrome, are particularly susceptible to sarcomas, including rhabdomyosarcomas. Our study aimed to identify rhabdomyosarcoma tumours that express Survivin, in order to test novel Survivin-targeted therapies in these tumours.

METHODS

Tumour microarray slides composed of 63 primary rhabdomyosarcoma tumours were stained with a polyclonal antibody to Survivin to identify tumours expressing Survivin. Subcutaneous tumours were then established in NOD/SCID mice using RH30(red) cells, a red fluorescent clone of the RH30 human alveolar rhabdomyosarcoma cell line. Tumours were treated by hydrodynamic injection with a cocktail of Survivin-shRNA-encoding plasmids for a period of 2 weeks.

RESULTS

Over 80% of primary rhabdomyosarcoma tumours expressed Survivin. Treatment of rhabdomyosarcoma xenografts showed greater than 70% reduction in growth when compared with control injected tumours at study completion (average tumour sizes: 1683 v 304 mm3, p<0.05).

CONCLUSIONS

Our findings support a role for Survivin in rhabdomyosarcoma biology and provide preliminary evidence for the therapeutic use of Survivin-targeted RNA interference for human tumours that express high levels of this molecule.

Fecal androgens of bison bulls during the rut

The influence of sex hormones is a key proximate factor underlying male reproductive behavior in mammals. Effective conservation policies for the remaining purebred plains bison (Bison bison bison) herds require knowledge of the physiology underlying bison reproductive biology. We used fecal steroid analysis to characterize androgen levels in adult bison bulls before, during, and after the rut, and to examine androgen levels of bulls differing in reproductive status, age, and mating success. Fieldwork was carried out at the Fort Niobrara National Wildlife Refuge in north-central Nebraska. All adult bison in the herd were individually known by unique brands. Fecal samples were collected during 2003 from bulls during pre-rut (June), rut (July-August), and post-rut (September), and behavioral observations focused on reproductive status and mating success during the rut. Matched sample data indicated that androgen levels (ng/g feces) of bulls peaked during the rut, doubling from pre-rut to rut and then declining by 75% during post-rut. Dominant bulls that tended (guarded) cows maintained higher androgen levels than bulls that were not tending. There was a positive correlation between bull age (associated with mating success) and androgens, with higher androgen levels in prime-aged bulls compared with younger bulls. Nonetheless, there was no correlation between mating success (measured by number of copulations observed) and androgen level. This suggests that while androgens may provide the proximate motivation to compete for matings, other factors determine the mating success of bison bulls.

Il-4 therapy prevents the development of proteinuria in active Heymann nephritis by inhibition of Tc1 cells

The role of IL-4, a key Th2 cytokine, in promoting or inhibiting active Heymann nephritis (HN) was examined. HN is induced by immunization with Fx1A in CFA, and proteinuria in HN is associated with subepithelial IgG and C3 deposition and infiltration of CD8(+) T-cytotoxic 1 (Tc1) cells and macrophages into glomeruli, as well as induction of Abs to Crry. Treatment with rIL-4 from the time of Fx1A/CFA immunization stimulated an earlier IgG1 response to Fx1A, induced anti-Crry Abs, and up-regulated IL-4 mRNA in lymphoid tissue, but did not alter proteinuria. Treatment with MRCOx-81, an IL-4-blocking mAb, resulted in greater proteinuria, which suggests endogenous IL-4 regulated the autoimmune response. Delay of rIL-4 treatment until 4 wk post-Fx1A/CFA immunization and just before the onset of proteinuria prevented the development of proteinuria and reduced Tc1 cell infiltrate in glomeruli. Delayed treatment with IL-4 had no effect on titer or isotype of Abs to Fx1A or on Ig, C3, and C9 accumulation in glomeruli. Treatment with rIL-13, a cytokine that alters macrophage function such as rIL-4, but has no direct effect on T or B cell function, reduced glomerular macrophage infiltrate, but did not prevent proteinuria or CD8+ T cell infiltrate. Anti-Crry Abs were paradoxically only induced with rIL-4 therapy, not in HN controls with proteinuria. It was concluded that the rIL-4 effect was probably by inhibition of Tc1 cells, which normally mediate the glomerular injury that results in proteinuria.

Reversal of experimental allergic encephalomyelitis with non-mitogenic, non-depleting anti-CD3 mAb therapy with a preferential effect on T(h)1 cells that is augmented by IL-4

This study examined whether therapy with a non-mitogenic, non-activating anti-CD3 mAb (G4.18) alone, or in combination with the T(h)2 cytokines, could inhibit induction or facilitate recovery from experimental allergic encephalomyelitis (EAE) in Lewis rats. G4.18, but not rIL-4, rIL-5 or anti-IL-4 mAb, reduced the severity and accelerated recovery from active EAE. A combination of rIL-4 with G4.18 was more effective than G4.18 alone. The infiltrate of CD4(+) and CD8(+) T cells, B cells, dendritic cells, and macrophages in the brain stem was less with combined G4.18 and IL-4 than G4.18 therapy or no treatment. Residual cells had preferential sparing of T(r)1 cytokines IL-5 and transforming growth factor-beta with loss of T(h)1 markers IL-2, IFN-gamma and IL-12Rbeta2, and the T(h)2 cytokine IL-4 as well as macrophage cytokines IL-10 and tumor necrosis factor-alpha. Lymph nodes draining the site of immunization had less mRNA for T(h)1 cytokines, but T(h)2 and T(r)1 cytokine expression was spared. Treatment with G4.18, rIL-4 or rIL-5 from the time of immunization had no effect on the course of active EAE. MRC OX-81, a mAb that blocks IL-4, delayed onset by 2 days, but had no effect on severity of active EAE. G4.18 also inhibited the ability of activated T cells from rats with active EAE to transfer passive EAE. This study demonstrated that T cell-mediated inflammation was rapidly reversed by a non-activating anti-CD3 mAb that blocked effector T(h)1 cells, and spared cells expressing T(h)2 and T(r)1 cytokines.

Mechanisms of induction of tolerance to organ allografts

The long-term acceptance of organ allografts can be induced in numerous rodent and some preclinical outbred models. Induction methods can use donor alloantigen in various forms, including spontaneous acceptance of grafts such as livers, to deviate the immune response so a subsequent graft will be accepted. Establishment of lymphohemopoietic chimerism is not essential. Short-term immunosuppressive treatments that prevent acute rejection can also induce tolerance. These include nonspecific immunosuppressive drugs and immunotherapy that blocks cell surface molecular interactions or cytokine function. There is variation in the effect of these protocols on different strain combinations that may be due to innate differences in the cell subpopulations and cytokines activated in the hosts. Th1 cytokines, although important in the mediation of rejection, are also required for induction of tolerance. Th2 cytokines may facilitate tolerance induction but are not essential. The tolerant state takes weeks to fully mature after exposure to alloantigen. Tolerance is associated with a loss or change in dendritic cells and the development of suppressor cells, which in all cases include CD4+ T cells. In the near future precise understanding of the function of these two cell types may allow diagnosis and induction of tolerance in clinical transplantation.

Alteration of nuclear factor-kappaB (NF-kappaB) expression in bone marrow stromal cells treated with etoposide

Bone marrow stromal cells are an essential regulatory component in the hematopoietic microenvironment. Regulation of hematopoietic cell development is mediated, in part, through interaction of progenitor cells with stromal cell vascular cell adhesion molecule-1 (VCAM-1). VCAM-1 expression has been shown to be driven primarily by binding of nuclear factor-kappaB (NF-kappaB) to two consensus binding sites in the promoter region. In this study, we show that down-regulation of VCAM-1 by the chemotherapeutic agent etoposide (VP-16) is associated with altered cellular localization of NF-kappaB. We demonstrated that VCAM-1 was diminished at the transcriptional level following treatment of stromal cells with VP-16, without alteration of VCAM-1 stability. Culture of bone marrow stromal cells in VP-16 resulted in reduced nuclear RelA (p65), a modest increase in nuclear NF-kappaB1 (p50), and reduced NF-kappaB binding to its DNA consensus sequence. Total levels of the NF-kappaB inhibitor Ikappa-Balpha were reduced during exposure to VP-16. Following removal of VP-16 from the culture, p65 and p50 nuclear profiles approximated those of untreated stromal cells, and VCAM-1 protein expression was restored. The current study indicates that NF-kappaB is a target molecule that is responsive to VP-16-induced damage in bone marrow stromal cells. As the primary transcription factor that promotes VCAM-1 expression, the observed changes in p65 and p50 cellular localization during treatment have a direct consequence for stromal cell function. The myriad of genes regulated by NF-kappaB, including both adhesion molecules and cytokines that contribute to stromal cell function, make chemotherapy-induced disruption of NF-kappaB biologically significant. Alterations in NF-kappaB activity may provide one measure by which the effects of aggressive treatment strategies on the bone marrow microenvironment can be evaluated.

Stromal cells regulate survival of B-lineage leukemic cells during chemotherapy

Approximately 20% of B-lineage acute lymphoblastic leukemias are not cured by traditional chemotherapy. The possibility was examined that residual leukemic cells that potentially contribute to relapse are harbored in association with fibroblastic stromal cells in the bone marrow. Modulation of cytarabine (Ara-C) and etoposide (VP-16) efficacy by bone marrow stromal cells in vitro was investigated. Stromal cell coculture was shown to sustain the proliferation of B-lineage leukemic cells and to reduce leukemic cell apoptosis when exposed to Ara-C or VP-16. Direct contact with stromal cells was essential for the protection of leukemic cells during chemotherapy, whereas soluble factors had negligible effect. Specifically, signaling mediated through interaction with the stromal cell adhesion molecule VCAM-1 was required to maintain the maximum viability of leukemic cells during Ara-C and VP-16 exposure. In contrast, the interaction of leukemic cells with fibronectin did not confer significant resistance to either chemotherapeutic agent. These observations suggest a role for the bone marrow microenvironment in modulating the response of B-lineage leukemic cells to Ara-C or VP-16, and they indicate specific molecular interactions that may be important in determining the sensitivity of leukemic cells to treatment. (Blood. 2000;96:1926-1932)

Induction of specific tolerance to allografts in rats by therapy with non-mitogenic, non-depleting anti-CD3 monoclonal antibody: association with TH2 cytokines not anergy

BACKGROUND

Anti-CD3 monoclonal antibodies (mAb) are potent immunosuppressives in transplantation but most do not induce tolerance. They induce anergy in Th1 cells but, if they bind to Fc receptors on antigen presenting cells, they activate T cells to release cytokines.

METHODS

This study examined the mechanisms of transplant tolerance induction to PVG fully allogeneic grafts in dark agouti rats by G4.18, a mouse immunoglobulinG3 anti-rat CD3 mAb that does not bind rat Fc receptors. Evidence of T cell activation was assayed by flow cytometry, reverse transcription (RT)-polymerase chain reaction (PCR) for cytokine mRNA, and responsiveness in mixed lymphocyte culture.

RESULTS

G4.18 treatment modulated T cell receptor/CD3 and CD2 and depleted T cells by <20% but did not induce activation surface markers. mRNA for interleukin (IL)-2, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and IL-4 in the lymph node, spleen, and thymus was not increased, and IFN-gamma mRNA was reduced. G4.18-treated and naive rat cells had similar proliferation and expression of IL-2, IFN-gamma, and IL-4 in vitro. G4.18-treated allograft recipients had no induction of mRNA for IL-2, IFN-gamma, TNF-alpha, TNF-beta, IL-4, IL-5, IL-10, perforin, and granzyme A & B in the spleen or grafts, with levels similar to those in isografts. The IL-4 and IL-5 mRNA levels in the spleen but not the graft of G4.18-treated recipients were higher than in rejecting and naive animals. Cells from G4.18-treated graft recipients proliferated more rapidly to the donor than to the third party and had increased IL-4 expression.

CONCLUSIONS

G4.18 induced transplant tolerance by a combination of modulation and blocking of the TCR/CD3, associated with increased Th2 cytokines, without depletion, induction of anergy, or nonspecific activation of T cells.

Mycophenolate mofetil prevents the induction of active Heymann nephritis: association with Th2 cytokine inhibition

The effect of mycophenolate mofetil (MMF) was examined in active Heymann nephritis (HN), an animal model of human membranous nephropathy. HN was induced in Lewis rats with Fx1A/complete Freund's adjuvant (CFA), and controls only received CFA. The induction of HN was prevented by MMF (30 mg/kg per d) from 0 to 4 wk after immunization. Proteinuria was not different in CFA controls up to 16 wk, and was significantly less than in untreated HN from 6 wk onward. Serum anti-Fx1A antibody (Ab) levels and glomerular Ig deposition were suppressed during therapy. The interstitial infiltrate of alphabetaTCR+, CD4+ and CD8+ T cells, natural killer cells, and macrophages (mphi) observed in untreated HN at 8 wk was absent from rats treated from 0 to 4 wk with MMF. Semiquantitative reverse transcription-PCR for renal mononuclear cell cytokine mRNA at 8 wk demonstrated that MMF from 0 to 4 wk prevented the increased expression of Th1 (interferon-gamma, lymphotoxin), Th2 (interleukin-4), and mphi (tumor necrosis factor-alpha) cytokines identified in untreated HN. In lymph node draining sites of immunization, MMF limited both enlargement and the increased proportion of CD3+, CD4+, and CD8+ T cells observed in untreated HN and CFA controls. MMF suppressed Th2 (interleukin-4) but not Th1 (interferon-gamma, lymphotoxin) cytokine mRNA expression in lymph nodes. MMF from 4 to 8, 6 to 12, or 10 to 14 wk did not prevent proteinuria, serum anti-Fx1A Ab, or glomerular IgG deposition when compared with untreated HN. This study showed that MMF from 0 to 4 wk prevented the induction of HN and was associated with preferential suppression of Th2 cytokines. This therapy may prove useful in human idiopathic membranous nephropathy.

Permanent CD8(+) T cell depletion prevents proteinuria in active Heymann nephritis

Active Heymann nephritis (HN) is a rat model of human idiopathic membranous nephropathy in which injury is thought to be mediated by membrane attack complex of complement (MAC) activated by antibody (Ab) to glomerular epithelial cells. Recent work has shown that HN develops in C6-deficient rats which cannot assemble MAC, and that infiltration of activated cytotoxic CD8(+) T cells and macrophages into glomeruli coincides with proteinuria. This study examined the role of CD8(+) T cells in mediating glomerular injury in HN by permanent CD8(+) cytotoxic T cell depletion via adult thymectomy (ATx) and anti-CD8 mAb. Groups of rats were depleted of CD8(+) T cells either before immunization for HN or 6 wk after immunization when Ab responses and glomerular IgG deposition were well established. These were compared with groups of HN, ATx/HN, and complete Freund's adjuvant (CFA) controls. Neither group of CD8(+) T cell-depleted rats developed proteinuria, although there was normal development and deposition of Ab. CD8(+) T cell-depleted rats developed neither T cell or macrophage infiltrates nor their effector cytokines, which are present in glomeruli of rats with HN. Examination of lymph node (LN) draining sites of immunization showed these findings were not explained by altered immune events within these LNs. It was concluded that CD8(+) cytotoxic T cells are essential to the mediation of glomerular injury in HN and may be relevant to the pathogenesis and treatment of membranous nephropathy.

Anti-CD4 monoclonal antibody-induced tolerance to MHC-incompatible cardiac allografts maintained by CD4+ suppressor T cells that are not dependent upon IL-4

Anti-CD4 mAb-induced tolerance to transplanted tissues has been proposed as due to down-regulation of Thl cells by preferential induction of Th2 cytokines, especially IL-4. This study examined the role of CD4+ cells and cytokines in tolerance to fully allogeneic PVG strain heterotopic cardiac allografts induced in naive DA rats by treatment with MRC Ox38, a nondepleting anti-CD4 mAb. All grafts survived >100 days but had a minor mononuclear cell infiltrate that increased mRNA for the Thl cytokines IL-2, IFN-gamma, and TNF-beta, but not for Th2 cytokines IL-4 and IL-6 or the cytolytic molecules perforin and granzyme A. These hosts accepted PVG skin grafts but rejected third-party grafts, which were not blocked by anti-IL-4 mAb. Cells from these tolerant hosts proliferated in MLC and produced IL-2, IFN-gamma, and IL-4 at levels equivalent to naive cells. Unfractionated and CD4+ T cells, but not CD8+ T cells, transferred specific tolerance to irradiated heart grafted hosts and inhibited reconstitution of rejection by cotransferred naive cells. This transfer of tolerance was associated with normal induction of IL-2 and delayed induction of IFN-gamma, but not with increased IL-4 or IL-10 mRNA. Transfer of tolerance was also not inhibited by anti-IL-4 mAb. This study demonstrated that tolerance induced by a nondepleting anti-CD4 mAb is maintained by a CD4+ suppressor T cell that is not associated with preferential induction of Th2 cytokines or the need for IL-4; nor is it associated with an inability to induce Th1 cytokines or anergy.

Treatment with interleukin-4 prolongs allogeneic neonatal heart graft survival by inducing T helper 2 responses

BACKGROUND

The T helper (Th) 2 cytokine interleukin (IL)-4 has been implicated as a major regulatory cytokine for the induction of transplant tolerance, but few studies have examined the capacity of IL-4 to induce tolerance. The effect of IL-4 therapy alone or with low doses of anti-CD4 monoclonal antibody (mAb) therapy on survival of fully allogeneic PVG neonatal heart graft in adult DA rats was examined.

METHODS

Rat recombinant (r) IL-4 was given at 30 microg (10(4) U)/kg daily intraperitoneally for 10 days and MRC OX35 (anti-CD4, nondepleting) or MRC OX81 (anti-IL-4) was given intraperitoneally on days 0, 3, 7, and 10. Semiquantitative reverse transcriptase-polymerase chain reaction was used to assay mRNA for cytokine in the graft, regional node and spleen and fluorescence-activated cell sorting was used to assay alloantibody Ig isotypes.

RESULTS

Grafts in rIL-4-treated rats survived a median period of 39 days (range, 28-52 days), significantly longer than in both untreated and nontransfected Chinese hamster ovary-K1 supernatant-treated controls (median, 14 days; range, 10-16 days, P=0.009). rIL-4 treatment with a suboptimal dose of anti-CD4 mAb prolonged median survival to 70 days (range, 63-80 days), which was longer than rIL-4 treatment alone or anti-CD4 mAb alone (median, 36 days; range, 30-55 days; P<0.0045). Combining MRC OX81 with MRC OX35 therapy led to earlier rejection at a median period of 26 days (range, 20-28 days); MRC OX81 alone had no effect on graft survival. Alloantibody titers, especially IgG1, were higher in rIL-4-treated animals and lower in anti-CD4 mAb-treated animals than in animals with normal rejection (P<0.05). IL-4 mRNA was increased in regional lymph nodes and spleen of the rIL-4-treated groups compared with all other groups, but there were no differences for IL-2, interferon-gamma, or IL-10.

CONCLUSIONS

rIL-4 therapy markedly prolonged neonatal cardiac allograft survival, and, with anti-CD4 therapy, it further prolonged survival. It induced IL-4 mRNA in lymphoid tissues and enhanced alloantibody production, especially IgG1, which demonstrated enhanced Th2 responses, but did not affect Th1 cytokines.

The cellular basis of cardiac allograft rejection: VIII. Mechanisms underlying delayed allograft rejection in PVG C6-deficient rats

BACKGROUND

The delayed allograft rejection in C6-deficient PVG C6- rats compared with normal PVG rats has been attributed to the lack of alloantibody activation of the membrane attack complex of complement. As T cells alone have been shown to effect graft rejection, we examined T-cell responses in PVG C6- rats.

METHODS

The cellular infiltrate and its mRNA for cytokines and effector molecules in DA heart allografts to PVG and PVG C6- rats was compared by immunoperoxidase staining and semiquantitative reverse transcriptase polymerase chain reaction. The ability of pure populations of T cells or alloantibody to mediate DA heart graft rejection in irradiated (750 rads) PVG and PVG C6- rats was also compared.

RESULTS

The median rejection time of DA heart allografts was 8 days in PVG rats and 17.5 days in PVG C6-. PVG C6- rats sensitized to DA by two skin grafts rejected DA heart grafts in 5-6 days. CD3+, CD4+, CD8+, interleukin-2 receptor-positive T cell, macrophage, and natural killer cell infiltration, as well as class II major histocompatibility complex and intercellular adhesion molecule-1 up-regulation, in grafts was similar in naive PVG and PVG C6- rats. mRNA for T helper 1 cytokine interleukin-2, interferon-gamma, tumor necrosis factor-beta, macrophage molecules tumor necrosis factor-alpha, and inducible nitric oxide synthase, as well as cytotoxic T-cell effector molecules perforin and granzyme A and B, were found to be the same in the grafts from both naive PVG and naive PVG C6- rats. Thus, there appeared to be no difference in the T-cell effector response between the PVG and PVG C6- groups. There were higher alloantibody titers in PVG C6- rats than in PVG hosts. Irradiation ablated rejection and alloantibody responses and reconstitution with naive T cells alone restored rejection in both PVG and PVG C6- rats. Irradiated rats given serum from PVG rats that had rejected DA grafts did not effect rejection of DA grafts even if given naive T cells. Sensitized T cells restored second set.

CONCLUSIONS

PVG C6- rats have normal T-cell responses and can mediate allograft rejection in the absence of alloantibody. The failure of PVG C6- to reject allografts rapidly may be a result of the poor clearance of alloantisera leading to enhancement of graft survival rather than a critical role for complement and membrane attack complex in acute rejection.

Induction of tolerance with nondepleting anti-CD4 monoclonal antibodies is associated with down-regulation of TH2 cytokines

BACKGROUND

Induction of tolerance with anti-CD4 has mainly focused on monoclonal antibodies (mAbs) that deplete CD4+ T cells. In this study, the mechanisms by which nondepleting anti-CD4 mAbs induce tolerance in the Dark Agouti to PVG rat heart graft model were examined.

METHODS

Five anti-CD4 mAbs were tested. Immunohistology and cytokine mRNA profiles were analyzed within grafts. Effects of combining anti-CD4 therapy with alloantibody (alloAb), interleukin (IL)-4, and anti-IL-4 mAb were also examined.

RESULTS

All mAbs tested induced indefinite graft survival (>150 days), with blocking of alloAb production. Exogenous alloAb did not restore rejection. Similar T cell receptor alphabeta+, CD8+, IL-2 receptor+ T cell, macrophage, and natural killer cell infiltration and comparable MHC II and intercellular adhesion molecule-1 levels were seen in rejecting and tolerant grafts. mRNA for IL-2, interferon-gamma, lymphotoxin, tumor necrosis factor-alpha, transforming growth factor-beta, cytolysin, and granzyme-A/B was comparable, although inducible nitric oxide synthase was slightly reduced in tolerant grafts. IL-4 and IL-5 were significantly reduced in tolerant grafts, although IL-6, IL-10, and IL-13 levels were similar; this was consistent with partial T helper (Th)2 response inhibition, which was also manifested by inhibited alloAb. The combination of alloAb, IL-4, or anti-IL-4 mAb with anti-CD4 did not prevent tolerance induction.

CONCLUSIONS

This study demonstrated that anti-CD4 mAb therapy did not inhibit activation and infiltration of Th1 and CD8+ effector T cells. Preferential induction of Th2 responses, especially IL-4, was not essential for the induction of tolerance. Our studies also found no evidence to support induction of anergy or transforming growth factor-beta as mechanisms of tolerance induction. These results question whether IL-4 is required for induction of transplantation tolerance.

Role of T cells in the mediation of Heymann nephritis. ii. Identification of Th1 and cytotoxic cells in glomeruli

The role of immunoglobulin (Ig) and complement as mediators of Heymann nephritis (HN) has been questioned by recent studies showing that HN can be induced in a C6-deficient rat that cannot assemble the membrane attack complex of complement. Also, the severity of HN can be reduced by therapy directed at CD8+ T cells, which has no effect on antibody (Ab) production or immune deposits. To identify whether T cells may contribute to the glomerular injury of active HN in Lewis rats, the mononuclear infiltrate and cytokine mRNA in glomeruli and kidney interstitium were examined. Groups of Lewis rats immunized with Fx1A in CFA developed HN, and were compared to controls that received CFA only. Proteinuria, the marker of glomerular filtration barrier dysfunction, was absent at four weeks but present at eight weeks in HN. Serum anti-Fx1A Ab and glomerular Ig were present in HN at both time points. Immunoperoxidase staining with monoclonal Abs identified, at eight weeks, a glomerular infiltrate of CD4+ and CD8+ T cells, and macrophages, but not NK cells. Semiquantitative RT-PCR of isolated glomeruli at eight weeks demonstrated expression of cytokine mRNA for Th1 CD4+ cells (IFN-gamma and TNF-beta/LT, but not IL-2), cytotoxic CD8+ T cells (granzyme A and perforin), and macrophages (TNF-alpha and IL-10), but not Th2 CD4+ cells (no increase in IL-4, IL-5 and IL-6). At eight weeks, the cellular infiltrate and pattern of cellular activation in glomeruli was different to that in renal cortex. In the cortical infiltrate CD8+ cells were a lesser component, and NK cells were increased, as were CD4+ cells and macrophages. RT-PCR identified increased cytokine mRNA for macrophages, Th1 and Th2 cells, but not cytotoxic effector T cells. At four weeks, T cells including CD4+ and CD8+ cells were identified in the isolated glomeruli of rats with HN, but there was no increase in cytokine mRNA expression. There was no infiltrate or increase in cytokine mRNA detected in renal cortex at four weeks. Anti-Fx1A Ab's and glomerular deposition of Ig develop many weeks before the onset of proteinuria, when there is only a small cellular infiltrate present. The progressive development of infiltrates of activated T cells, principally Th1 and cytotoxic effector cells, and macrophages, within glomeruli is coincident with the development of proteinuria. These findings raise the possibility that these cells contribute to the mediation of the glomerular injury and proteinuria of HN.

Threshold for occluded formaldehyde patch test in formaldehyde-sensitive patients. Relationship to repeated open application test with a product containing formaldehyde releaser

Our purpose was to investigate the eliciting threshold concentration of formaldehyde in formaldehyde-sensitive individuals in the occluded and non-occluded patch test, and to evaluate the relationship to repeated open application test (ROAT) with a product containing a formaldehyde releaser. 20 formaldehyde-sensitive patients and a control group of 20 healthy volunteers were included in the study. Occluded and non-occluded patch tests with formaldehyde solutions from 25 to 10,000 ppm, and ROAT for 1 week with a leave-on cosmetic product containing on average 300 ppm formaldehyde, were carried out simultaneously on each subject. In the occluded patch test, 1/2 of the 20 patients only reacted to 10,000 ppm formaldehyde, 9 reacted to 5,000 ppm, 3 reacted to 1,000 ppm, 2 reacted to 500 ppm and 1 reacted to 250 ppm. No definite positive reactions were observed in the non-occluded patch test or in the ROAT. No positive reactions were observed in the control group to any of the test procedures. We concluded that the threshold concentration for occluded patch test to formaldehyde in formaldehyde-sensitive patients was 250 ppm. The threshold in occluded patch test corresponded to the degree of sensitivity. Definite positive reactions in the ROAT were not seen, either indicating that they are unlikely to happen with the type of product used or that the exposure time was too short.

Active Heymann nephritis in complement component C6 deficient rats

The mechanisms of renal injury that result in proteinuria in active Heymann nephritis (AHN) remain unclear, though data suggest that in analogy of the passive form of the disease the membrane attack complex C5b-9 may be involved. AHN was induced in an inbred strain of PVG/c-rats that are totally deficient in the C6 component of complement and are unable to form the lytic C5b-9 complex, as well as in non-complement deficient PVG/c+ rats that are immunologic identical to the deficient strain. In both groups of animals comparably high titers of anti-Fx1A autoantibodies were found after three weeks and persisted at 40 weeks. Proteinuria was also similar in both groups, and was first evident at six weeks. High levels of urinary protein, ranging from 200 mg/24 hr to 500 mg/24 hr, were found after 10 weeks and persisted up to one year. Renal biopsy findings at various times post-immunization were identical in both groups, including immunofluorescence staining for Ig and C3 deposits, and also EM findings of subepithelial electron-dense deposits were not different. The injection of heterologous rabbit complement, that partially and temporarily restored the CH50 activity in PVG/c- rats did not alter or hasten the disease. Long-term follow-up showed that all rats in both groups continued to have severe proteinuria and that most animals died between 8 to 12 months after disease induction, without renal impairment. EM findings in serial biopsies demonstrated that the growth of the subepithelial deposits as measured by surface area occurred between weeks 4 and 12. A positive correlation (r = 0.94) between the size of the deposits and the level of proteinuria was found. These studies demonstrate that the membrane attack complex of complement does not play a major role in AHN. The relationship of the size of the immune deposits to the level of proteinuria suggests that the growth of the immune deposits on itself initiate secondary mechanisms that damage the permselective characteristics of the glomerular membrane.

Cardiac allograft vascular disease. Relationship to microvascular cell surface markers and inflammatory cell phenotypes on endomyocardial biopsy

BACKGROUND

Cardiac allograft vascular disease is characterized by accelerated and diffuse intimal proliferation involving both the microvasculature and epicardial vessels. Because in vivo documentation of this complication is now possible with intracoronary ultrasound imaging, we can examine the relationship of intimal proliferation to markers of immunity and endothelial activation. We hypothesize that alterations of microvascular cell surface markers likely mirror changes in the epicardial vessels that may be important in the pathophysiology of intimal proliferation.

METHODS AND RESULTS

Forty-three heart transplant patients were examined by intracoronary ultrasound more than 1 year after transplantation, and these images were analyzed to obtain mean intimal thickness and intimal thickness class (I through IV), calculated from the mean thickness and circumferential involvement. Right ventricular endomyocardial biopsies obtained at the time of intracoronary ultrasound were examined by immunohistochemistry to detect microvascular expression of histocompatibility leukocyte antigen (HLA) classes I and II (HLA ABC, DR, DP, and DQ); endothelial-specific antigen detected by the monoclonal antibody E 1.5; intercellular adhesion molecules (ICAM-1); CD4+ and CD8+ lymphocytes and macrophages (CD 14+). Microvascular antigen expression was graded 1 through 5 on the basis of the diffuseness of positive staining. The number of each inflammatory cell phenotype present per high-power field was counted. By ANOVA, scores for HLA DR, HLA DQ, and E1.5 expression were lower in intimal thickness classes II, III, and IV compared with class I. This inverse relationship was significant by linear regression analysis of mean intimal thickness. Inflammatory cells were not significantly correlated with intimal thickening. Rejection incidence was higher, and time since transplantation longer, in intimal thickness classes II, III, and IV compared with class I.

CONCLUSION

Transplant coronary artery intimal proliferation is associated with alteration of microvascular endothelial cell surface markers. These changes in cell surface antigen expression could provide the substrate for coronary artery intimal proliferation and narrowing.

A monoclonal antibody (A6) recognizing a unique epitope restricted to CD45RO and RB isoforms of the leukocyte common antigen family identifies functional T cell subsets

The mAb A6 was produced by immunization of mice with human PHA-stimulated PBMC. Immunoprecipitation studies and staining of cell lines transfected with individual leukocyte common antigen (LCA) isoforms showed that A6 recognizes a unique epitope strongly expressed on the lower MW isoform (p180) of LCA, but also weakly expressed on the p190 isoform coded by exon B and the p205 coded by exons A and B. The epitope recognized by A6 was carbohydrate-dependent in that it was neuraminidase-sensitive, but trypsin-resistant. A6 strained most TCR-alpha beta+ cells with differential intensities, subdividing them into a bright and dim population, and strongly stained all TCR-gamma delta+ cells. A6 did not stain CD19+ B cells nor CD56+ NK cells. Anti-CD45 mAb such as UCHL1 recognizing CD45RO have been used to define memory T cells. Depletion of PBMC subsets with A6 or UCHL1 mAb dramatically decreased proliferative responses to the recall antigens anti-CD3 mAb and alloantigen and enhanced their responses to PHA. A6, unlike UCHL1, also depleted alloreactive T cells that affect primary and secondary MLC and CML. Thus, A6 was shown to recognize the lower MW isoforms of LCA which are expressed on functional T cell subsets including memory, activated, and alloreactive T cells.

Hereditary C6 deficiency in a strain of PVG/c rats

A chance observation has led to the discovery of a strain of PVG rats (PVG/c-) which are deficient in complement (C) component C6. Analysis of total haemolytic activity (CH50) of PVG/c- serum revealed an absent CH50 activity compared with serum of other rat strains and of a PVG/c rat (PVG/c+) that showed normal C activity. Thus, the PVG/c- rat was unable to activate the C5b-9 membrane attack complex. To gain insight into the complement abnormalities, analysis of individual C components was performed. Testing the PVG/c- serum in a C6 haemolytic assay and using deficient human sera showed a deficiency of C6 in the PVG/c- rat. Highly purified human C6 and human sera deficient in other components were able to reconstitute the CH50 activity of the PVG/c- rat. The possibility that an inactivator of C was present in PVG/c- serum was excluded. The deficiency was found to be inheritable and under the control of an autosomal recessive gene. Furthermore, tissue antigens and immunity of the PVG/c- rat were found to be identical to those determined in the PVG/c+ rat. With regard to their health status, the PVG/c- animals seem to have no disadvantages compared with PVG/c+ rats when held under the same conditions within the protected environment of animal facilities. Taken together, both rat strains provide an unique animal model for studying the biological role of C, particularly the C5b-9 membrane attack complex in experimental medicine.

Induction of tolerance to heart allografts in rats using posttransplant total lymphoid irradiation and anti-T cell antibodies

This study examined whether posttransplant anti-T cell monoclonal or polyclonal antibody therapy could provide a window of treatment to allow posttransplant total lymphoid irradiation (TLI) to induce tolerance. These experiments were conducted in a high responder strain combination of an ACI cardiac allograft into a Lewis rat. In this situation, treatment with antibody or posttransplant TLI alone is insufficient to induce tolerance, while similar treatments alone have been shown to induce tolerance in low responder strains. The affects of three anti-T cell therapies were compared: anti-CD4 mAb therapy, anti-CD3 mAb, and rabbit antithymocyte globulin (RATG). None of these antibody therapies alone prolonged graft survival indefinitely. Combining anti-CD4 therapy with posttransplant TLI markedly delayed rejection but failed to induce long-term graft survival. Tolerance could be induced by a combination of anti-pan T cell antibody (anti-CD3) and TLI, and, all grafts survived beyond 100 days. RATG failed to prevent graft rejection when used alone or in combination with TLI. However, posttransplant therapy with a combination of RATG, TLI, and single-donor blood transfusion resulted in graft survival beyond 100 days. Recipients bearing long-term donor grafts rejected third-party (PVG) grafts within 2 weeks. Low density donor bone marrow cells used instead of a blood transfusion did not facilitate tolerance. The results indicate that monoclonal or polyclonal anti-pan T cell antibodies, TLI, and a donor blood cell infusion function synergistically in facilitating tolerance to allografts in the posttransplant period.

Induction of long-term specific tolerance to allografts in rats by therapy with an anti-CD3-like monoclonal antibody

Monoclonal antibodies to CD3 have been shown to activate T cells in vivo and in vitro but have also been shown to render T cells anergic in vitro. In this study G4.18, a mouse IgG3 mAb, was produced that appeared to recognize CD3 by its binding to all peripheral T cells, including a population not recognized by mAb to TCR-alpha/beta that was presumed to be TCR-gamma/delta cells. It precipitated molecules in the 24-26 kd region consistent with the CD3 complex as well as molecules approximately 45 and approximately 49 kd that corresponded to TCR alpha and beta chains and a 92-kd complex. Incubating T cells for 24 hr with saturating concentrations of G4.18 caused modulation of the TCR complex. In vitro, it activated T cells but only if prebound to plastic. In solution it inhibited MLC and CML, but not PHA or Con A activation. In vivo, G4.18 was not toxic even in high doses, and this was thought to be due to the inability of this mAb to activate T cells in vitro because the rat lacks Fc receptors for mouse IgG3. Therapy with G4.18 resulted in transient modulation of TCR/CD3 on T cells and depletion of these cells from blood. G4.18 had no depleting effects by lymph node or spleen cells but caused marked, transient thymic involution. Therapy with G4.18 also induced indefinite survival (> 100 days) of PVG (RTIc) heart grafts but not skin grafts in DA (RTIa) hosts. These hosts with long-surviving cardiac transplants, when grafted from PVG skin, accepted these grafts but rejected third-party skin in first-set. Thus G4.18 was shown to induce long-term specific tolerance to an organ allograft.

Elevated levels of tumor necrosis factor-alpha in the nephrotic syndrome in humans

To investigate the possible role of cytokines in the mediation of glomerular injury in the nephrotic syndrome, the levels of interleukin (IL)-1 beta, IL-2, interferon (IFN)-alpha, IFN-gamma, and tumor necrosis factor-alpha (TNF-alpha) were measured in patients with primary nephrotic syndrome. These patients had minimal change nephropathy (MCN), focal and segmental glomerulosclerosis (FSGS), or membranous nephropathy (MN) on biopsy. Cytokine levels were assessed by immunoradiometric assays, and specimens consisted of plasma, urine, and the culture supernate of mitogen-stimulated peripheral blood mononuclear cells (PBMC). Only TNF-alpha was found to be significantly elevated, in the plasma and urine of patients with FSGS and MN, above that found in healthy control subjects and patients with MCN. The elevation of TNF-alpha could not be shown to correlate with the length or severity of the nephrotic syndrome or with loss of body mass. IL-1 beta, IL-2, IFN-alpha, and IFN-gamma levels were not elevated. In culture, mitogen-stimulated PBMC from all three groups of nephrotic subjects released an excess of TNF-alpha compared with controls, a response not consistently observed for the other cytokines measured. The findings of this survey of cytokine levels in nephrotic patients support the possibility that TNF-alpha may play a pathogenic role in the induction or maintenance of glomerular barrier dysfunction in humans.

Specific unresponsiveness in rats with prolonged cardiac allograft survival after treatment with cyclosporine. VI. In vitro alloreactivity of T cell subsets from rats with long-surviving allografts

DA rats treated with a short course of cyclosporine develop specific unresponsiveness to RT1-incompatible PVG donor heart allografts. CD4+ cells, not CD8+ cells, transfer unresponsiveness to irradiated rats. However, host-derived CD8+ cells are important in reestablishing unresponsiveness. In this study, unfractionated lymphoid cells and W3/25+ (CD4+) cells from CsA-treated rats with long-surviving PVG allografts demonstrated normal alloreactivity to PVG alloantigen in the mixed lymphocyte culture and failed to suppress the proliferative response of naive W3/25+ cells to donor-specific alloantigen. MRC OX8+ (CD8+) cells did not proliferate. Sera from CsA-treated rats had no effect on the MLC reactivity of cells from CsA-treated rats, suggesting that blocking or antiidiotypic antibodies did not diminish alloreactivity. IL-2 production by W3/25+ cells from CsA-treated rats was similar to that by W3/25+ cells from naive rats. Specific cytotoxic T cells to PVG were generated in MLC, and the frequency of precursor cytotoxic lymphocytes in CsA-treated rats was similar to that in naive DA rats. In an in vitro assay testing response to idiotype, neither W3/25+ or MRC OX8+ cells from unresponsive rats proliferated. As CD4+ cells from CsA-treated rats lose their capacity to adoptively transfer specific unresponsiveness unless maintained in a cytokine-rich supernatant, all in vitro assays were performed with and without added cytokines, but no change in reactivity consistent with suppression was observed in any assay. CD4+ suppressor cells had no effect on conventional in vitro assays of alloreactivity, preventing the detection of the unresponsiveness in vitro.

Specific unresponsiveness in rats with prolonged cardiac allograft survival after treatment with cyclosporine. V. Dependence of CD4+ suppressor cells on the presence of alloantigen and cytokines, including interleukin 2

CD4+ cells from CsA-treated DA rats with long-surviving PVG heart allografts specifically suppress the capacity of naive CD4+ cells to restore allograft rejection in irradiated DA rats, but have normal donor-specific alloreactivity in MLC. CD4+ suppressor cells from CsA-treated DA rats cultured for 3 days against either PVG or DA spleen cells lost the capacity to transfer suppression into irradiated DA rats grafted with PVG hearts and regained the ability to mediate rejection. However, these cells retained suppressor function when stimulated with donor-specific alloantigen in media supplemented with 20% Con A supernatant. CD4+ cells from CsA-treated rats cultured against either third-party stimulator cells or syngeneic cells expressing anti-PVG idiotype in media supplemented with Con A supernatant failed to maintain suppressor cell function. CD4+ cells from CsA-treated rats cultured in media supplemented with Con A supernatant alone also failed to maintain suppressor function. Suppressor cell function in culture was not maintained by rIL-2. mAb to the IL-2 receptor alpha chain (CD25) prevented the maintenance of suppressor cell function in media supplemented with Con A supernatant. Con A supernatant is rich in IFN-gamma, but addition of an anti-IFN-gamma mAb to the culture did not affect the maintenance of suppressor cells. These studies demonstrate that the CD4+ suppressor cell from CsA-treated rats with long-surviving grafts is short-lived; its survival is dependent upon contact with specific alloantigens and cytokines, one of which is IL-2. In the absence of cytokines and/or specific alloantigen, the CD4+ cells regain the capacity to initiate graft rejection in irradiated rats, suggesting that within the CD4+ subpopulation there is a fragile balance between cells with the capacity to suppress and effect rejection.

Presence of methylated adenine in GATC sequences in chromosomal DNAs from Campylobacter species

We digested chromosomal DNAs from 12 Campylobacter strains (C. jejuni, 4 strains; C. coli, 2 strains; C. fetus subsp. fetus, 2 strains; C. hyointestinalis, 2 strains; and C. upsaliensis, 2 strains) and from 4 Helicobacter strains (H. pylori, 2 strains; and H. mustelae, 2 strains) with HindIII, SstI, BamHI, DpnI, MboI, and Sau3AI. Restriction fragments were then separated by electrophoresis in 1% agarose or 10% polyacrylamide gels. Only DNAs from three Campylobacter species (C. jejuni, C. coli, and C. upsaliensis) were digested with DpnI (an enzyme that recognizes only methylated adenine in GATC sequences). We used MboI and Sau3AI to confirm these findings.

Short-term responsiveness of membranous glomerulopathy to cyclosporine

We administered a 12-week course of cyclosporine (CsA) (4 to 6 mg/kg/24 h) to nephrotic patients with membranous glomerulopathy (MG). Nephrotic patients with minimal change nephropathy (MCN) served as a comparison group. We evaluated the effects of CsA on proteinuria, glomerular function, and the release of cytokines by peripheral blood mononuclear cells in culture. Proteinuria was restored to normal levels within 2 to 4 weeks in MCN. Proteinuria declined from nephrotic to subnephrotic levels (< 3,500 mg/24 h) in 10 of 14 patients with MG, also within 2 to 4 weeks of onset of therapy. The four nonresponders exhibited a rapidly progressive and presumably irreversible form of MG culminating in renal failure. On average, fractional clearances of albumin and IgG declined by 59% and 73% in MG (P < 0.005); corresponding declines in MCN were by 99% (P < .0001). Corresponding rates of glomerular filtration in each glomerular injury remained unchanged. A strong trend for proteinuria to relapse after CsA was withdrawn was evident in both disorders. The release of tumor necrosis factor (TNF)-alpha by mononuclear cells in culture was enhanced in each glomerular injury, both before and after the course of CsA. We conclude that the proteinuria in most cases of MG exhibits a responsiveness to CsA that is qualitatively similar to, but less complete than, that in MCN. The rapidity with which barrier function improves suggests a possible role for cell-mediated immune injury in MG.

The role of T cells in the mediation of glomerular injury in Heymann's nephritis in the rat

Heymann's nephritis (HN), a rat model of the membranous glomerulonephritis in man, is thought to be mediated by auto-Ig with subsequent activation of C. Whether T cell mechanisms are involved in the mediation of HN, apart from CD4+ cells providing help for auto-Ig production, was examined by treatment with mAb specific for T cell subsets for 6 weeks after immunization to induce HN. Anti-CD4 mAb therapy totally prevented proteinuria, in that at 6, 8, and 12 week treated rats had less than 15 mg/day of protein compared to controls that all had greater than 260 mg/day. Ig and C deposition in the glomerulus was significantly less and auto-Ig titers in serum were partially suppressed by anti-CD4 therapy. Anti-CD8 mAb therapy markedly reduced proteinuria at all time points, for example at 6 weeks there was 51 +/- 40 mg/day compared to 183 +/- 120 mg/day (P = 0.0003), but had no effect on auto-Ig titers or on Ig and C deposition in the glomerulus. A non-specific effect of high dose mouse mAb therapy was excluded by the findings that a mAb that did not bind to rat cells had no effect on the induction of HN and that serum C was not depleted in any of the mAb treated animals. A role for T effector mechanisms was further supported by the finding that therapy with mAb to T cell receptor alpha/beta chain or with cyclosporine also markedly delayed the onset of proteinuria. Examination of renal biopsies showed a T cell infiltrate in glomeruli and the interstitium of the untreated HN controls that was not present in MRC Ox35 or MRC Ox8 treated groups. This infiltrate included CD4+ and CD8+ T cells and macrophages. These results suggest induction of proteinuria in HN was totally dependent upon CD4+ T cells, and that CD4+ and CD8+ cells may have a direct role in the mediation of glomerular dysfunction in HN.