Evaluation of Iron Deficiency Using Reticulocyte Indices in Dogs Enrolled in a Blood Donor Program

Background

People donating blood more than twice annually are at risk of developing iron deficiency. Little is known about the iron status of dogs enrolled in blood donor programs.

Hypothesis

Dogs donating blood ≥6 times annually will show evidence of iron deficiency based on their reticulocyte indices.

Animals

Thirteen dogs enrolled in a blood donor program donating ≥6 times over the preceding 12 months and 20 healthy nondonor control dogs.

Methods

Prospective observational study. Mature red blood cell (RBC) indices, reticulocyte indices, serum iron, serum ferritin, and total iron‐binding capacity (TIBC) were compared between groups.

Results

Packed cell volume (median 47%, range 40–52%, P < .01), hematocrit (median 46.4%, range 40.3–52.5%, P < .01), and reticulocyte count (median 16,000/μL, range 9,000–38,000/μL, P < .01) were significantly lower in the blood donor dogs. No statistically significant differences were noted in the mature RBC indices between groups. Both reticulocyte mean corpuscular volume (median 88.8 fL, range 83.4–95.5 fL, P = .03) and reticulocyte hemoglobin content (median 24.6 pg, range 23.1–26.6 pg, P < .01) were significantly lower in the blood donor group. Serum iron and ferritin were similar between groups; however, TIBC was significantly higher in the control group (median 403 μg/dL, range 225–493 μg/dL, P = .02).

Conclusions

The findings in dogs donating ≥6 times annually suggest the presence of iron‐deficient erythropoiesis in this population.

Quantification of circulating house dust mite-specific IL-4- and IL-13-secreting T cells correlates with rhinitis severity in asthmatic children and varies with the seasons

BACKGROUND

Defining suitable markers to diagnose and monitor allergy and its severity is essential to correctly assign patients for specific immunotherapy. Circulating levels of specific IgE are good markers of sensitization, but not of clinically symptomatic allergy.

OBJECTIVE

To quantify circulating interleukin (IL)-4- and IL-13-secreting T cells specific for house dust mite (HDM) in children presenting HDM-allergic asthma associated or not with rhinitis and correlate results with clinical symptoms.

METHODS

We analysed 26 children with HDM respiratory disease (allergic rhinitis and asthma) together with six children with non-allergic asthma. Peripheral blood mononuclear cells were stimulated with HDM extract in a 24-h ELISpot assay to quantify the number of HDM-specific IL-4- and IL-13-secreting T cells. Asthma severity and control, and rhinitis severity were scored according to the Global Initiative for Asthma (GINA) and the Allergic Rhinitis and its Impact on Asthma (ARIA) Guidelines.

RESULTS

The number of HDM-specific IL-4- and IL-13-secreting T cells was higher in patients with allergic asthma as compared to patients with non-allergic asthma. It varied with the season of blood sampling with two peaks in the fall and early spring. Independently of the season, the number of HDM-specific IL-4-secreting T cells correlated with rhinitis severity (OR = 2; 95% IC:1.1-3.8; P = 0.04).

CONCLUSIONS AND CLINICAL RELEVANCE

Allergen-specific IL-4- and IL-13-producing T cells were only detected in HDM-allergic asthmatic children (not in patients with non-allergic asthma). Their numbers correlated with clinical severity of allergic rhinitis.

Induction of allograft tolerance by monoclonal CD3 antibodies: a matter of timing

Despite remarkable progress in organ transplantation through the development of a wealth of immunosuppressive drugs highly effective at controlling acute rejection, two major problems still remain, the loss of transplants due to chronic rejection and the growing number of sensitized recipients due to previous transplants, transfusions or pregnancies. Induction of immune tolerance appears to be the only way to curb this complex situation. Here we describe that a therapy, already successfully used to restore immune tolerance to self-antigens in overt autoimmunity, is effective at promoting transplant tolerance. We demonstrate that a short low-dose course with CD3 antibodies started after transplantation, at the time of effector T cell priming to alloantigens, induces permanent acceptance of fully mismatched islet allografts. Mechanistic studies revealed that antigen-specific regulatory and effector T cells are differentially affected by the treatment. CD3 antibody treatment preferentially induces apoptosis of activated alloreactive T cells which is mandatory for tolerance induction. In contrast, regulatory T cells are relatively spared from CD3 antibody-induced depletion and can transfer antigen-specific tolerance thus arguing for their prominent role in sustaining long-term graft survival.

The 'hygiene hypothesis' for autoimmune and allergic diseases: an update

According to the 'hygiene hypothesis', the decreasing incidence of infections in western countries and more recently in developing countries is at the origin of the increasing incidence of both autoimmune and allergic diseases. The hygiene hypothesis is based upon epidemiological data, particularly migration studies, showing that subjects migrating from a low-incidence to a high-incidence country acquire the immune disorders with a high incidence at the first generation. However, these data and others showing a correlation between high disease incidence and high socio-economic level do not prove a causal link between infections and immune disorders. Proof of principle of the hygiene hypothesis is brought by animal models and to a lesser degree by intervention trials in humans. Underlying mechanisms are multiple and complex. They include decreased consumption of homeostatic factors and immunoregulation, involving various regulatory T cell subsets and Toll-like receptor stimulation. These mechanisms could originate, to some extent, from changes in microbiota caused by changes in lifestyle, particularly in inflammatory bowel diseases. Taken together, these data open new therapeutic perspectives in the prevention of autoimmune and allergic diseases.

99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: immune therapies of type 1 diabetes: new opportunities based on the hygiene hypothesis

Insulin-dependent (type 1) diabetes is a prototypic organ-specific autoimmune disease resulting from the selective destruction of insulin-secreting beta cells within pancreatic islets of Langerhans by an immune-mediated inflammation involving autoreactive CD4(+) and CD8(+) T lymphocytes which infiltrate pancreatic islets. Current treatment is substitutive, i.e. chronic use of exogenous insulin which, in spite of significant advances, is still associated with major constraints (multiple daily injections, risks of hypoglycaemia) and lack of effectiveness over the long term in preventing severe degenerative complications. Finding a cure for autoimmune diabetes by establishing effective immune-based therapies is a real medical health challenge, as the disease incidence increases steadily in industrialized countries. As the disease affects mainly children and young adults, any candidate immune therapy must therefore be safe and avoid a sustained depression of immune responses with the attendant problems of recurrent infection and drug toxicity. Thus, inducing or restoring immune tolerance to target autoantigens, controlling the pathogenic response while preserving the host reactivity to exogenous/unrelated antigens, appears to be the ideal approach. Our objective is to review the major progress accomplished over the last 20 years towards that aim. In addition, we would like to present another interesting possibility to access new preventive strategies based on the 'hygiene hypothesis', which proposes a causal link between the increasing incidence of autoimmune diseases, including diabetes, and the decrease of the infectious burden. The underlying rationale is to identify microbial-derived compounds mediating the protective activity of infections which could be developed therapeutically.

Increased stimulatory capacity of spleen cells from adult thymectomized mice in mixed lymphocyte reactions

Conflicting results have been reported concerning the effect of adult thymectomy (A-Tx) on the mixed lymphocyte reaction (MLR) response. Our purpose was to test the reverse question, namely the effect of A-Tx on the stimulatory capacity of mouse lymphocytes carrying allelic disparities at the Mls and the H-2 loci. Spleen cells from A-Tx CBA donors were found to be significantly more stimulating than cells from normal donors. That A-Tx could eliminate suppressor T cells involved in MLR regulation or in preventing back stimulation is not likely according to our data. An increment in expression or in accessibility of Mls or H-2 antigenic determinants induced by A-Tx is no more likely, since a smilar increase in lymphocyte proliferation was observed in syngeneic cultures. The most probable explanation remains that A-Tx discloses a strongly stimulatory subpopulation, perhaps acting in part nonspecifically. The hypothesis of an enrichment in B cells versus a loss of T cells is not compatible with our findings, since B-cell-enriched fractions from various origins never attained the stimulating ability disclosed by A-Tx cells. Moreover, the cell involved is theta-positive, although slightly nylon-wool-adherent, and thus shares several properties with immature T cells involved in auto-rosette formation.

Detection of hepatitis B antigen in circulating immune complexes in acute and chronic hepatitis

By using polyethylene glycol precipitation at low concentration (PEG test) and the radiolabeled C1q binding test, immune complexes were detected sera from acute (23/28) and chronic (28/32) hepatitis patients, hemodialyzed patients with chronic hepatitis B surface (HBs) antigenemia (7/19), and asymptomatic HBs antigen carriers (2/11). After treatment of PEG precipitates with acidic pH, heating, or proteolytic enzyme (protease), electroimmunodiffusion or radioimmunoassay revealed the presence of HBs antigen or antibody in dissociated immune complexes in sera from several acute and chronic hepatitis patients. Electron microscopy showed immune complexes of HB virus in 9 of 12 PEG precipitates obtained from PEG-test-positive sera; these 9 precipitates were from patients with acute or chronic hepatitis and the other three from chronic HBs Ag carriers. Free HB virus particles were observed after protease digestion of PEG precipitates. Neither immune complexes nor virus particles were seen in precipitates from PEG-test-negative but HBs-Ag-positive sera from chronic carriers.

Cellular and molecular signals in T cell differentiation

The thymic epithelium exerts its differentiative effects through several mechanisms, involving direct contact with stem cells as well as secretion of various thymic hormones. Indirect and direct evidence suggests that the thymus produces chemotactic factors for the stem cells that colonize the thymus anlage. The epithelium also produces several maturational factors which act upon stem cells that have undergone primary differentiation by contact with thymic epithelium. The chemical characteristics of these hormones and their mode of action at the cellular level (high affinity receptors, metabolic effects, target cells) are partly known. Their relationship with T cell factors such as Interleukin-2--produced in the periphery and endowed with strong differentiative capacity--is intriguing, the more so because thymic hormones not only act within the thymus but also affect peripheral T cells after they have emigrated from the thymus.

[Therapeutic monoclonal antibodics]

Less than ten years after the discovery of hybridomas by Kohler and Milstein in 1975, the first monoclonal antibody was injected in humans to prevent graft rejection. The antibodies used were targeted against the CD3 molecule involved in the transduction of T cell signals after recognition of the antigen. Paradoxically, because of pharmaceutical hesitations later found to be unwarranted, the therapeutic class developed slowly. It was not until the 1990s that other formulations emerged. In parallel, work was undertaken to modify the antibodies using genetic engineering techniques to humanize the molecules by changing the majority of the species determinants from the murine producing animals to the human recipients. It was even found possible to produce totally human antibodies using several different strategies based on in vitro phage display. This led to rapid development of new antibodies used for a wide range of indications: organ transplantation (anti-CD2, anti-CD4, antiCD25, antiCD40L), as well as anti-respirator syncytial virus (RSV) for respiratory infections, and anti cancer agents (Anti-CD20 antibodies and anti-tumor antibodies), as well as autoimmune diseases (with significant success with anti-TNF antibodies). It was found the monoclonal antibodies offer an exceptionally effective method in domains where conventional compounds have reached their limit. This specific action of monoclonal antibodies, with fine specificity for the targets (which can be varied to infinity), as well as their capacity to provide positive signals to cells whose functions are not often inhibited by small molecules. An illustration of this mode of action is the effect recently demonstrated by our team on restored self tolerance using anti-CD3 antibodies in newly diagnosed diabetics in whom sustained remission can be injected after less than one week's treatment.

Exacerbated Th2-mediated airway inflammation and hyperresponsiveness in autoimmune diabetes-prone NOD mice: a critical role for CD1d-dependent NKT cells

The NOD mouse has proved to be a relevant model of insulin-dependent diabetes mellitus, closely resembling the human disease. However, it is unknown whether this strain presents a general biastoward Th1-mediated autoimmunity or remains capable of mounting complete Th2-mediated responses. Here, we show that NOD mice have the capacity to develop a typical Th2-mediated disease, namely experimental allergic asthma. In contrast to what might have been expected, they even developed a stronger Th2-mediated pulmonary inflammatory response than BALB/c mice, a strain that shows a typical Th2 bias in this model. Thus, after allergen sensitization and intra-nasal challenge, the typical features of experimental asthma were exacerbated in NOD mice, including enhanced bronchopulmonary responsiveness, mucus production and eosinophilic inflammation in the lungs as well as specific IgE titers in serum. These hallmarks of allergic asthma were associated with increased IL-4, IL-5, IL-13 and eotaxin production in the lungs, as compared with BALB/c mice. Notwithstanding their quantitative and functional defect in NOD mice, CD1d-dependent NKT cells contribute to aggravate the disease, since in OVA-immunized CD1d(-/-) NOD mice, which are deficient in this particular T cell subset, airway eosinophilia was clearly diminished relative to NOD littermates. This is the first evidence that autoimmune diabetes-prone NOD mice can also give rise to enhanced Th2-mediated responses and might thus provide a useful model for the study of common genetic and cellular components, including NKT cells that contribute to both asthma and type 1 diabetes.

A thymulin analogue peptide with powerful inhibitory effects on pain of neurogenic origin

The effects of a synthetic peptide analog of thymulin (PAT) were tested on nociceptive behavior in two animal models for peripheral mononeuropathy and in another two models for capsaicin-induced hyperalgesia. Treatment with PAT (0.25-25 microg/rat, i.p.) produced significant reduction of the mechanical allodynia and heat hyperalgesia in rats subjected to either chronic constriction injury (CCI) or spared nerve injury (SNI) models for mononeuropathy. Cold allodynia was moderately reduced in the CCI model. The inhibition of neuropathic manifestations peaked at 1-2 h post-treatment and disappeared in 3-4 h. Daily treatment with PAT, however, produced progressive attenuation of all neuropathic manifestations in the SNI model. On the other hand, pretreatment with similar doses of PAT produced dose-dependent reduction of the hyperalgesia induced by intraplantar injection of capsaicin (10 microg in 50 microl). The highest dose of PAT (50 microg) produced significant reduction of abdominal aversive behavior induced by i.p injection of capsaicin (20 microg in 100 microl). Compared with the effects of treatment with morphine or meloxicam (injected at single doses known to produce analgesia), PAT exerted equal or stronger inhibitory effects on neuropathic manifestations. The reported results suggest a possible direct action of PAT on afferent nerve fibers but its mechanisms remain to be determined.

[Prevent and cure insulin-dependent diabetes]

Insulin-dependent mellitus diabetes is an autoimmune disease resulting from the destruction of the beta cells of the islets of Langerhans by autoreactive T cells. Various approaches are being investigated in order to slow down the progression of diabetes using immunotherapy. The most promising results are based on the induction of specific tolerance following the administration of soluble autoantigens or monoclonal anti-CD3 antibodies. These strategies, initially developed in the NOD mouse, have been proven to be efficacious in recently diagnosed diabetics.

[Current concepts of autoimmunity]

Autoimmunity is physiological: in every normal individual autoreactive T cells and B cells which produce natural autoantibodies, exist. Auto-immunity becomes pathological, giving rise to an autoimmune disease, when the number of autoreactive cells, and particularly the avidity of their receptors for autoantigens increase. Triggering of the disease depends both on the increase in immunogenicity of the target cell, which may be secondary to a viral infection, and the individual's own capability to recognize the antoantigens (HLA genes, T cell repertoire). More rarely, the disease is caused by an infectious agent leading to a crossed reaction with an autoantigen (Guillain-Barré syndrome). Nevertheless, all these elements are not sufficient to provoke a chronic disease such as multiple sclerosis or myasthenia gravis. The passage to chronicity is usually secondary to a defect in immunoregulation. Several categories of regulatory T cells have been found: Th2 cells, CD25+ cells, Trl cells, NKT cells. It is still difficult to asses the responsibility of the defect of one of these populations in a given disease, or to single out the cytokines implicated, although an essential role is often given to interleukin 10 and/or TGFB. Even if the pathogenic autoimmune reaction is triggered by the autoantigens of the target cell, there is apparently not a unique autoantigen target. The specificity of the reaction spreads progressively from one antigen, which may vary among subjects, to the entire target cell. It is based on these notions that new immunotherapeutic approaches for autoimmune diseases are being developed (soluble autoantigens, or one of their modified peptides: (APL), cytokine, anti-CD3 antibody).

Immunotherapy of insulin-dependent diabetes mellitus

Immunotherapy of diabetes is now focusing on induction of tolerance to beta cell antigens using either soluble antigens or monoclonal anti-T-cell antibodies. These approaches have reached the clinical arena. At the experimental level, strategies are being developed that use or target cytokines (with gene therapy) or stimulate regulatory T cells.

Activation of natural killer T cells by alpha-galactosylceramide treatment prevents the onset and recurrence of autoimmune Type 1 diabetes

Type 1 diabetes (T1D) in non-obese diabetic (NOD) mice may be favored by immune dysregulation leading to the hyporesponsiveness of regulatory T cells and activation of effector T-helper type 1 (Th1) cells. The immunoregulatory activity of natural killer T (NKT) cells is well documented, and both interleukin (IL)-4 and IL-10 secreted by NKT cells have important roles in mediating this activity. NKT cells are less frequent and display deficient IL-4 responses in both NOD mice and individuals at risk for T1D (ref. 8), and this deficiency may lead to T1D (refs. 1,6-9). Thus, given that NKT cells respond to the alpha-galactosylceramide (alpha-GalCer) glycolipid in a CD1d-restricted manner by secretion of Th2 cytokines, we reasoned that activation of NKT cells by alpha-GalCer might prevent the onset and/or recurrence of T1D. Here we show that alpha-GalCer treatment, even when initiated after the onset of insulitis, protects female NOD mice from T1D and prolongs the survival of pancreatic islets transplanted into newly diabetic NOD mice. In addition, when administered after the onset of insulitis, alpha-GalCer and IL-7 displayed synergistic effects, possibly via the ability of IL-7 to render NKT cells fully responsive to alpha-GalCer. Protection from T1D by alpha-GalCer was associated with the suppression of both T- and B-cell autoimmunity to islet beta cells and with a polarized Th2-like response in spleen and pancreas of these mice. These findings raise the possibility that alpha-GalCer treatment might be used therapeutically to prevent the onset and recurrence of human T1D.

Tolerance to islet autoantigens in type 1 diabetes

Tolerance to beta cell autoantigens represents a fragile equilibrium. Autoreactive T cells specific to these autoantigens are present in most normal individuals but are kept under control by a number of peripheral tolerance mechanisms, among which CD4(+) CD25(+) CD62L(+) T cell-mediated regulation probably plays a central role. The equilibrium may be disrupted by inappropriate activation of autoantigen-specific T cells, notably following to local inflammation that enhances the expression of the various molecules contributing to antigen recognition by T cells. Even when T cell activation finally overrides regulation, stimulation of regulatory cells by CD3 antibodies may reset the control of autoimmunity. Other procedures may also lead to disease prevention. These procedures are essentially focused on Th2 cytokines, whether used systemically or produced by Th2 cells after specific stimulation by autoantigens. Protection can also be obtained by NK T cell stimulation. Administration of beta cell antigens or CD3 antibodies is now being tested in clinical trials in prediabetics and/or recently diagnosed diabetes.

Non-Th2 regulatory T-cell control of Th1 autoimmunity

The Th1/Th2 concept brought an attractive explanation of the active self tolerance which appears to control the onset of pathogenic autoimmunity. New data coming from various independent horizons indicate that self immunoregulation could also depend to a large extent on non-Th2 cells. Original data derived from the day-3-thymectomy model, selective T-cell lymphocytopenia and nonobese diabetic mice are discussed in an effort to analyze similarities and differences in phenotype (CD25, CD62L and CD45RB) and cytokine pattern (notably interleukin (IL)-4, IL-10 and transforming growth factor (TGF)beta) of regulatory cells involved in these models. The relationship of these cells with Th3, Tr1 and natural killer (NK) T cells are also discussed. The hypothesis is proposed that CD25 CD62L T cells mediate the physiologic regulation of self regulation whereas Th2 and Th3 cells are essentially induced following sensitization against autoantigens.

In vivo blockade of the Fas-Fas ligand pathway inhibits cyclophosphamide-induced diabetes in NOD mice

There is compelling evidence to show that insulin dependent diabetes ensues from selective apoptosis of pancreatic beta-cells mediated by autoreactive T-lymphocytes. The respective implication in this phenomenon of the various apoptotic pathways driven by Fas, perforin, or tumor necrosis factor is still ill- defined. Here we took advantage of the cyclophosphamide-induced model of accelerated diabetes in NOD mice to explore the physiopathological role of the Fas-Fas Ligand pathway. A single injection of cyclophosphamide (200 mg/kg) to 7-8 week-old prediabetic NOD mice triggered diabetes within 10-15 days in 85-100% of the animals. Cyclophosphamide also induced a significant decrease in spleen T cells, that was most evident by days 6-10 after treatment, and selectively affected the CD3(+)CD62L(+)compartment that includes immunoregulatory T cells. To block the in vivo Fas-Fas ligand (Fas L) interaction we administered a biologically active recombinant fusion protein coupling mouse Fas to the Fc portion of human IgG1 (FAS-Fc). Mice treated with FAS-Fc (10 doses iv of 15 microg) starting on the day of cyclophosphamide injection up to day 22, were fully protected from disease. Unexpectedly this protective effect was not due to blockade of Fas-FasL-mediated beta-cell apoptosis but rather to the inhibition of the cyclophosphamide effect on T cells. Indeed FAS-Fc treatment prevented the drug-induced T cell depletion in general and that of immunoregulatory T cells in particular. Additionally, FAS-Fc administration limited to the phase of beta-cell destruction did not afford any protection.

Anti-titin antibodies in myasthenia gravis: tight association with thymoma and heterogeneity of nonthymoma patients

BACKGROUND

Titin is the major autoantigen recognized by anti-striated muscle antibodies, which are characteristic of generalized myasthenia gravis (MG).

OBJECTIVE

To seek a correlation between anti-titin antibodies and other features of MG patients, including histopathology, age at diagnosis, anti-acetylcholine receptor (anti-AChR), autoantibody titers, and clinical severity.

METHODS

A novel, highly specific radioligand assay was performed on a large group of 398 patients with generalized MG.

RESULTS

Among thymectomized patients, anti-titin antibodies were present in most patients with thymoma (56/70 [80%]), contrasting with only a minority of patients with thymus atrophy or hyperplasia (17/165 [10%]). They were also present in 64 (41%) of 155 nonthymectomized patients who had a radiologically normal thymus. In these patients and in those who had a histologically normal thymus, anti-titin antibodies were associated with a later age at onset of disease and with intermediate titers of anti-AChR antibodies. After controlling for these 2 variables, disease severity was not significantly influenced by anti-titin antibodies.

CONCLUSIONS

Anti-titin antibodies are a sensitive marker of thymoma associated with MG in patients 60 years and younger, justifying the insistent search for a thymoma in MG patients of this age group who have these antibodies. In nonthymoma patients, anti-titin antibodies represent an interesting marker complementary to the anti-AChR antibody titer, identifying a restricted subset of patients. These clinical correlations should prompt further studies to examine the mechanisms leading to the production of anti-titin antibodies.

Protective role of infections and vaccinations on autoimmune diseases

Infectious agents may induce autoimmune disease through several mechanisms, notably antigen mimicry and inflammation of the target organ; conversely, infections may protect from autoimmune diseases. This paradoxical effect has been demonstrated for a number of bacteria, viruses and parasites on a variety of spontaneous or experimentally induced animal models of autoimmune diseases (e.g. experimental allergic encephalomyelitis, lupus mice, non-obese diabetic mice). The mechanisms of the protection are still ill-defined, and probably vary according to models. Stimulation of immunoregulatory CD4 T cells has been shown to play a central role in several major models. The role of superantigens is also important, like that of Toll-like receptors. Antigen competition is another major mechanism, itself open to several interpretations. Epidemiological data support a protective role of infections on human allergic and autoimmune diseases. These diseases are much more common in countries with high socio-economic development (typically Northern countries in Europe). The reason for this cannot be fully explained by genetic differences because migrating populations develop these diseases with the same incidence of the adoptive country rather than that of the country of origin. It is interesting that the frequency of these diseases has been increasing in developed countries over the last 20 years but not in undeveloped ones.

The activity of immunoregulatory T cells mediating active tolerance is potentiated in nonobese diabetic mice by an IL-4-based retroviral gene therapy

Splenocytes from nonobese diabetic mice overexpressing murine IL (mIL)-4 upon recombinant retrovirus infection lose their capacity to transfer diabetes to nonobese diabetic-scid recipients. Diabetes appeared in 0-20% of mice injected with mIL-4-transduced cells vs 80-100% of controls injected with beta-galactosidase-transduced cells. Protected mice showed a majority of islets (60%) presenting with noninvasive peri-insulitis at variance with beta-galactosidase controls that exhibited invasive/destructive insulitis. Importantly, in all recipients, the transduced proteins were detected within islet infiltrates. Infiltrating lymphocytes from recipients of mIL-4-transduced cells produced high levels of mIL-4, as assessed by ELISA. In recipients of beta-galactosidase-transduced cells, approximately 60% of TCRalphabeta(+) islet-infiltrating cells expressed beta-galactosidase, as assessed by flow cytometry. The protection from disease transfer is due to a direct effect of mIL-4 gene therapy on immunoregulatory T cells rather than on diabetogenic cells. mIL-4-transduced purified CD62L(-) effector cells or transgenic BDC2.5 diabetogenic T cells still transferred disease efficiently. Conversely, mIL-4 transduction up-regulated the capacity of purified immunoregulatory CD62L(+) cells to inhibit disease transfer. These data open new perspectives for gene therapy in insulin-dependent diabetes using T cells devoid of any intrinsic diabetogenic potential.

NKT lymphocyte ontogeny and function are impaired in low antibody-producer Biozzi mice: gene mapping in the interval-specific congenic strains raised for immunomodulatory genes

NKT cells are CD4(+) or CD4(-)CD8(-) CD1d-restricted lymphocytes, characterized by the property to rapidly produce IL-4 and IFN-gamma in response to TCR ligation. This IL-4 burst is lacking in autoimmunity-prone SJL and NOD strains of mice, which suggests an immunoregulatory role for NKT cells. The NKT cell status was thus investigated in the genetically selected high (H) and low (L) antibody-producer mice. The results show that (i) the frequency of cells expressing the NKT cell markers is 3- to 4-fold lower in thymus and spleen from L than H mice, (ii) L mice spleen cells did not produce IL-4 following injection of anti-TCR alpha beta antibody, and (iii) L mice thymus and spleen cells failed to produce IL-4 after in vitro stimulation by anti-TCR alpha beta antibody or alpha-galactosylceramide, a newly described NKT cell ligand. These parameters were investigated in six interval-specific congenic strains raised for the quantitative trait loci which contain the immunomodulatory genes responsible for the high/low antibody production phenotypes. IL-4 production recovery occurred only in the congenic strain in which the H origin chromosome 4 segment was introgressed on the L background. This finding was not due to increased NKT cell frequency but appeared dependent of antigen-presenting cells in co-culture experiments. This result strongly suggests the presence of gene(s) modulating NKT function on chromosome 4, close to several genes predisposing to autoimmunity.

Autoantibodies in recent onset type-1 diabetic patients to a Mr 60K microsomal hepatic protein: new evidence for autoantibodies to the type-2 glucose transporter

Here we describe the presence of IgG antibodies, in the sera of patients presenting with insulin-dependent diabetes mellitus (IDDM), that react in Western blots with a 60-kD protein (Mr 60K) from rat hepatic microsomal extracts. Sera from 60 IDDM patients were screened and 31.6% were positive for the Mr 60K band. This antibody reactivity was indistinguishable in terms of both molecular weight and isoelectric point (pI 5.4) from that described in some patients presenting with autoimmune hepatitis who may also develop IDDM. We hypothesized that the type-2 glucose transporter (Glut-2) that is expressed on both hepatocytes and pancreatic beta cells could be a putative target for the detected antibodies. A polyclonal antisera to rat Glut-2 used in the liver microsome Western blot identified a 60-kD band superimposable upon that evidenced by IDDM sera. Antisera to Glut-2 successfully inhibited the binding of the patient's IgGs to liver microsomes, further suggesting that the two proteins may be identical. Using protein extracts from a rat insulinoma cell line (RIN) transfected with the human Glut-2 cDNA, further evidence was obtained suggesting that these IDDM IgGs are specific for the human Glut-2 transporter.

A subset of NKT cells that lacks the NK1.1 marker, expresses CD1d molecules, and autopresents the alpha-galactosylceramide antigen

In the present report, we characterize a novel T cell subset that shares with the NKT cell lineage both CD1d-restriction and high reactivity in vivo and in vitro to the alpha-galactosylceramide (alpha-GalCer) glycolipid. These cells preferentially use the canonical Valpha14-Jalpha281 TCR-alpha-chain and Vbeta8 TCR-beta segments, and are stimulated by alpha-GalCer in a CD1d-dependent fashion. However, in contrast to classical NKT cells, they lack the NK1.1 marker and express high surface levels of CD1d molecules. In addition, this NK1.1(-) CD1d(high) T subset, further referred to as CD1d(high) NKT cells, can be distinguished by its unique functional features. Although NK1.1(+) NKT cells require exogenous CD1d-presenting cells to make them responsive to alpha-GalCer, CD1d(high) NKT cells can engage their own surface CD1d in an autocrine and/or paracrine manner. Furthermore, in response to alpha-GalCer, CD1d(high) NKT cells produce high amounts of IL-4 and moderate amounts of IFN-gamma, a cytokine profile more consistent with a Th2-like phenotype rather than the Th0-like phenotype typical of NK1.1(+) NKT cells. Our work reveals a far greater level of complexity within the NKT cell population than previously recognized and provides the first evidence for T cells that can be activated upon TCR ligation by CD1d-restricted recognition of their ligand in the absence of conventional APCs.

Comparative immunoreactivity of anti-trifluoroacetyl (TFA) antibody and anti-lipoic acid antibody in primary biliary cirrhosis: searching for a mimic

Previous studies documenting the existence of cross-reactivity between the lipoated (but not unlipoated) forms of the inner lipoyl domain (E2L2) of PDC-E2 [the major autoantigen in Primary biliary cirrhosis (PBC)] and trifluoroacetylated (TFA) proteins, led us to hypothesize that PBC may be due to an initial insult with an environmental agent that cross-reacts with TFA. Therefore, we performed a comparative study of the reactivity of rabbit anti-TFA antibody and anti-lipoic acid (LA) antibody against the mitochondrial autoantigens of human PBC and various TFA and LA conjugated proteins. Whereas both anti-TFA and anti-LA reacted with PDC-E2, the wild-type lipoated form of E2L2, OGDC-E2, E3-BP and LA-KLH, neither reacted with BCOADC-E2 or the non-lipoated form of E2L2. Of interest was that while anti-TFA reacted with PDC-E2, TFA-RSA and LA-KLH, it failed to inhibit PDC-E2 enzyme function. In contrast, anti-LA demonstrated cytoplasmic and mitochondrial staining, and inhibited PDC enzyme activity. Hence, although considerable cross reactivity exists between anti-TFA and anti-LA, the molecular nature of the interaction is clearly different. One of 14 PBC sera reacted weakly with TFA-albumin, whereas four of 14 PBC sera reacted with LA-KLH. Immunohistochemically, both anti-TFA and anti-LA antibodies reacted focally with periportal hepatocytes and bile ducts in both PBC and controls. However, anti-LA produced much stronger focalized staining of the bile ducts of diseased liver. This study suggests that while anti-TFA antibody recognizes lipoic acid-linked enzymes and proteins, the epitope recognized differs from that of anti-LA antibody and PBC autoantibodies. It is unlikely that a response to TFA is the triggering event in PBC. Anti-LA antibodies share a higher degree of similarity to PBC sera providing suggestive evidence that anti-LA antibodies or anti-LA like antibodies (mimotopes) may help define the initiator of the autoimmune response.

Autoantibodies associated with acute rejection after liver transplantation for type-2 autoimmune hepatitis

Autoantibodies, markers of autoimmune diseases, can also be detected in chronic allograft rejection. However, the appearance of these autoantibodies in acute rejection after orthotopic liver transplantation has not yet been reported. Liver-kidney-microsome type-1 (LKM-1) antibodies directed against the autoantigen cytochrome CYP2D6 define a group of patients with autoimmune hepatitis type-2 (AIH-2), distinct from autoimmune hepatitis type-1 (AIH-1) in which anti-nuclear antibodies and anti-smooth muscle antibodies (SMA) with actin specificity are present in patient sera. Autoantibodies were studied by the quantitative CYP2D6 radioligand assay (RLA) that uses a radiolabeled CYP2D6 as antigen, immunoblotting using recombinant CYP2D6 protein and human liver microsomal and cytosolic fractions, and indirect immunofluorescence (IIF) using rat kidney-stomach-liver cryostat sections. In addition, the specificity of anti-SMA was detected by IIF on HEp2 cell line harvested with colchicin. This report describes the time course of CYP2D6 antibodies and the appearance of anti-SMA (without anti-actin, cytokeratin and vimentin reactivity) associated with acute rejection during a 2-year follow-up, in a patient who underwent transplantation at end-stage type 2 autoimmune hepatitis. In addition, we report a new reactivity against an unknown 40-kDa protein using a rat cytosolic fraction. The detection of autoantibodies in sequential samples may be important to better predict rejection or relapse, and to establish adequate therapy.

Genetic and physical mapping of a type 1 diabetes susceptibility gene (IDDM12) to a 100-kb phagemid artificial chromosome clone containing D2S72-CTLA4-D2S105 on chromosome 2q33

Polymorphic markers within the CTLA4 gene on chromosome 2q33 have been shown to be associated with type 1 diabetes. Therefore, a gene responsible for the disease (IDDM12) most likely lies within a region of <1-2 cM of CTLA4. To define more precisely the IDDM12 interval, we genotyped a multiethnic (U.S. Caucasian, Mexican-American, French, Spanish, Korean, and Chinese) collection of 178 simplex and 350 multiplex families for 10 polymorphic markers within a genomic interval of approximately 300 kb, which contains the candidate genes CTLA4 and CD28. The order of these markers (D2S346, CD28, GGAA19E07, D2S307, D2S72, CTLA4, D2S105, and GATA52A04) was determined by sequence tagged site content mapping of bacterial artificial chromosome (BAC) and yeast artificial chromosome (YAC) clones. The transmission disequilibrium test (TDT) analyses of our data revealed significant association/linkage with three markers within CTLA4 and two immediate flanking markers (D2S72 and D2S105) on each side of CTLA4 but not with more distant markers including the candidate gene CD28. Tsp analyses revealed significant association only with the three polymorphic markers within the CTLA4 gene. The markers linked and associated with type 1 diabetes are contained within a phagemid artificial chromosome clone of 100 kb, suggesting that the IDDM12 locus is either CTLA4 or an unknown gene in very close proximity.

Quantitative radioligand assays using de novo-synthesized recombinant autoantigens in connective tissue diseases: new tools to approach the pathogenic significance of anti-RNP antibodies in rheumatic diseases

OBJECTIVE

To describe new assays for the detection and quantification of antibodies to RNPs in rheumatic diseases, using soluble nuclear antigens synthesized de novo in reticulocyte lysates.

METHODS

Sera from 381 patients with various rheumatic diseases, including 212 patients with systemic lupus erythematosus (SLE), were analyzed in order to evaluate the sensitivity and specificity of serum autoantibody reactivities to several recombinant soluble autoantigens: U1-A RNP, Sm-B, SSA/Ro 52 and SSA/Ro 60, SSB/La, and Ku. Radioligand assays (RLAs) were performed following the in vitro transcription and translation of each autoantigen from the corresponding complementary DNA, labeled with 35S-methionine. The radiolabeled protein was then bound by the specific serum autoantibody, forming immune complexes that were captured by protein A-Sepharose beads and quantified by counting the radioactivity.

RESULTS

Among the SLE patients, 44% were positive for anti-U1-A RNP activity, 34% for anti-Sm-B, 44% for anti-SSA (32% for Ro 52 and 46% for Ro 60), 32% for anti-SSB/La, and 11% for anti-Ku reactivities. SSA antibodies had a high frequency in patients with mixed connective tissue disease (MCTD) (80%); 65% of these patient sera reacted with Ro 52, 45% with Ro 60, and 45% with U1-A RNP. Twenty percent of the MCTD patients also exhibited antibodies to Sm-B and Ku. In patients with Sjögren's syndrome, anti-SSA was the main anti-RNP antibody (63%), together with SSB/La antibodies (44%). Among patients with inflammatory myopathy, only antibodies against Ro 52 (36%) and Ro 60 (36%) were present. These new RLA allowed observation of a strong correlation (P < 0.0001) between Sm-B antibody levels and the severity of SLE (as measured by the SLE Disease Activity Index), and establishment of a correlation between anti-U1-A RNP antibodies and the occurrence of SLE nephritis (P < 0.02). All RLAs were highly specific for the antigen tested and displayed, in the disease groups studied, a higher sensitivity than conventional immunodiffusion assays.

CONCLUSION

These highly sensitive, specific, and quantitative RLAs represent new tools for the detection of autoantibodies to RNP antigens in rheumatic diseases, and may be useful for (differential) diagnosis in clinical practice.

Presence of antinucleosome autoantibodies in a restricted set of connective tissue diseases: antinucleosome antibodies of the IgG3 subclass are markers of renal pathogenicity in systemic lupus erythematosus

OBJECTIVE

To study the frequency and disease specificity of antinucleosome antibody reactivity in diverse connective tissue diseases (CTD), and to determine factors, such as antibody subclass, that may influence the pathogenicity of these antibodies in relation to disease activity.

METHODS

IgG and IgM antinucleosome activities on nucleosome core particles from 496 patients with 13 different CTD and 100 patients with hepatitis C were measured by enzyme-linked immunosorbent assay (ELISA). Of the patients with CTD, 120 had systemic lupus erythematosus (SLE), 37 had scleroderma (systemic sclerosis; SSc), 20 had mixed connective tissue disease (MCTD), and 319 had other CTD, including Sjögren's syndrome, inflammatory myopathy, rheumatoid arthritis, primary antiphospholipid syndrome, Wegener's granulomatosis, Takayasu arteritis, giant cell arteritis, relapsing polychondritis, Behçet's syndrome, and sarcoidosis. Antinucleosome-positive sera were further analyzed, by isotype-specific ELISA, for antinucleosome and anti-double-stranded DNA (anti-dsDNA) IgG subclasses.

RESULTS

SLE, SSc, and MCTD were the only 3 CTD in which antinucleosome IgG were detected (71.7%, 45.9%, and 45.0% of patients, respectively). Antinucleosomes of the IgG3 subclass were present at high levels in patients with active SLE and were virtually absent in those with SSc, MCTD, or inactive SLE, and their levels showed a positive correlation with SLE disease activity. Of note, an increase in levels of antinucleosome of the IgG3 isotype was observed during SLE flares, and this increase was found to be closely associated with active nephritis. Levels of antinucleosome of the IgG1 subclass showed a trend toward an inverse correlation with SLE disease activity. No significant fluctuation in the anti-dsDNA isotype profile was observed in relation to SLE severity or clinical signs.

CONCLUSION

Our data suggest that IgG antinucleosome is a new marker that may help in the differential diagnosis of CTD; antinucleosome of the IgG3 isotype might constitute a selective biologic marker of active SLE, in particular, of lupus nephritis.

Granulocyte-colony stimulating factor treatment of lupus autoimmune disease in MRL-lpr/lpr mice

G-CSF not only functions as an endogenous hemopoietic growth factor for neutrophils, but also displays pro-Th2 and antiinflammatory properties that could be of therapeutic benefit in autoimmune settings. We evaluated the effect of treatment with G-CSF in a murine model of spontaneous systemic lupus erythematosus, a disease in which G-CSF is already administered to patients to alleviate neutropenia, a common complication. Chronic treatment of lupus-prone MRL-lpr/lpr mice with low doses (10 microg/kg) of recombinant human G-CSF, despite the induction of a shift toward the Th2 phenotype of the autoimmune response, increased glomerular deposition of Igs and accelerated lupus disease. Conversely, high-dose (200 microg/kg) treatment with G-CSF induced substantial protection, prolonging survival by >2 mo. In the animals treated with these high doses of G-CSF, neither the Th1/Th2 profile nor the serum levels of TNF-alpha and IL-10 were modified. Despite the presence of immune complexes in their kidney glomeruli, no inflammation ensued, and serum IL-12 and soluble TNF receptors remained at pre-disease levels. This uncoupling of immune complex deposition and kidney damage resulted from a local down-modulation of FcgammaRIII (CD16) expression within the glomeruli by G-CSF. Our results demonstrate a beneficial effect of high doses of G-CSF in the prevention of lupus nephritis that may hold promise for future clinical applications, provided caution is taken in dose adjustment.

Poly(ADP-ribose) polymerase alleles in French Caucasians are associated neither with lupus nor with primary antiphospholipid syndrome. GRAID Research Group. Group for Research on Auto-Immune Disorders

OBJECTIVE

To investigate the putative involvement of poly(ADP-ribose) polymerase (PARP) alleles in systemic lupus erythematosus (SLE) and primary antiphospholipid syndrome (APS).

METHODS

This study of French Caucasians included 171 unrelated patients with SLE, 88 unrelated patients with primary APS, and 193 ethnically matched healthy controls. The SLE group comprised 89 patients with sporadic SLE and 82 patients with familial SLE. Patients' and controls' DNA were genotyped for the various alleles of a polymorphic CA dinucleotide repeat located within the promoter region of PARP.

RESULTS

No statistically significant difference was observed for the distribution of PARP alleles between the healthy control group and each patient group or the pooled SLE patient group.

CONCLUSION

The study findings strongly suggest that these alleles do not influence susceptibility to SLE or primary APS in French Caucasians.

Truncating mutations in CCM1, encoding KRIT1, cause hereditary cavernous angiomas

Cavernous angiomas are vascular malformations mostly located in the central nervous system and characterized by enlarged capillary cavities without intervening brain parenchyma. Clinical symptoms include seizures, haemorrhage and focal neurological deficits. Cavernous angiomas prevalence is close to 0.5% in the general population. They may be inherited as an autosomal dominant condition in as much as 50% of cases. Cerebral cavernous malformations (CCM) loci were previously identified on 7q, 7p and 3q (refs 4,5). A strong founder effect was observed in the Hispano-American population, all families being linked to CCM1 on 7q (refs 4,7). CCM1 locus assignment was refined to a 4-cM interval bracketed by D7S2410 and D7S689 (ref. 8). Here we report a physical and transcriptional map of this interval and that CCM1, a gene whose protein product, KRIT1, interacts with RAP1A (also known as KREV1; ref. 9), a member of the RAS family of GTPases, is mutated in CCM1 families. Our data suggest the involvement of the RAP1A signal transduction pathway in vasculogenesis or angiogenesis.

Identification of peptides from autoantigens GAD65 and IA-2 that bind to HLA class II molecules predisposing to or protecting from type 1 diabetes

Type 1 diabetes is a T-cell-mediated disease in which presentation of autoantigens to CD4+ T-cells is thought to play a crucial role. Polymorphism of HLA class II genes accounts for 50% of the genetic risk of contracting type 1 diabetes. HLA-DQ and -DR molecules predisposing to or protecting from type 1 diabetes have been identified, but the molecular basis controlling these associations is as yet undefined. Apart from distinct thymic selection of autoreactive T-cells by susceptible and protective HLA molecules, exclusive presentation of autoantigenic peptides by type 1 diabetes-predisposing HLA molecules or, alternatively, induction of regulatory T-cells by protective alleles are potential mechanisms for modification of type 1 diabetes risk by HLA polymorphism. As a first step in exploring the role of HLA molecules in autoantigen-specific cellular responses in type 1 diabetes, we have screened peptides covering the sequence of two major autoantigens targeted by humoral and cellular immune responses, GAD65 and islet associated-2 (IA-2), for binding to class II molecules. We developed a sensitive novel competition binding assay allowing us to measure peptide binding on intact cells to 10 HLA-DR and 4 HLA-DQ molecules. For all tested alleles, multiple peptides binding with high affinity were identified. We report clustering of binding peptides in the COOH-terminal regions of GAD65 and IA-2, as well as highly promiscuous binding patterns of some peptides. Our results demonstrate that most peptides derived from the GAD and IA-2 autoantigens can bind to both type 1 diabetes-predisposing and type 1 diabetes-protective HLA molecules, although some exceptions were observed. The binding inventory presented here for GAD and IA-2 peptides can be useful for mapping natural epitopes and predicting peptide-specific responses induced by preventive immunization.

CD3 antibody-induced IL-10 in renal allograft recipients: an in vivo and in vitro analysis

BACKGROUND

The first administration of CD3 monoclonal antibodies, such as anti-human CD3 (OKT3), induces a massive release of several cytokines, including tumor necrosis factor alpha (TNF-alpha), interferon (IFN)-gamma, interleukin (IL)-2, IL-3, IL-6, and granulocyte-macrophage colony-stimulating factor.

METHODS

Cytokine levels in patient's sera were measured by specific ELISA. In vitro cultures were performed using OKT3-stimulated peripheral blood mononuclear cells and/or whole blood from patients and normal controls.

RESULTS

Here we describe that OKT3 administration to human renal allograft recipients also leads to a significant release of IL-10. Contrasting with most OKT3-induced cytokines, such as TNF-alpha whose release is transient, IL-10 levels show a more progressive increase, they peak only by 4-8 hr after the first OKT3 injection and persist longer. Thus, significant IL-10 levels are still detectable at the time of the second and the third OKT3 injection. Administration of corticosteroids, 1 hr before the first OKT3 injection, significantly reduced both TNF-alpha and IL-10 release. Experiments were performed to evaluate the source(s) of IL-10 and its (their) influence on the initial T-cell activation. When stimulated in culture with soluble OKT3, the production of IL-10 was dependent on the cooperation between T lymphocytes and monocytes. It is important that, as assessed through the use of a specific neutralizing antibody, the endogenous IL-10 produced in the co-culture system exerted a negative feed-back on the release of the other pro-inflammatory CD3-induced cytokines, which was reproducible.

CONCLUSION

These results are supportive of a major role of IL-10 in the down-modulation of the OKT3-triggered T-cell activation cascade.

IL-7 up-regulates IL-4 production by splenic NK1.1+ and NK1.1- MHC class I-like/CD1-dependent CD4+ T cells

NK T cells are an unusual subset of T lymphocytes. They express NK1. 1 Ag, are CD1 restricted, and highly skewed toward Vbeta8 for their TCR usage. They express the unique potential to produce large amounts of IL-4 and IFN-gamma immediately upon TCR cross-linking. We previously showed in the thymus that the NK T subset requires IL-7 for its functional maturation. In this study, we analyzed whether IL-7 was capable of regulating the production of IL-4 and IFN-gamma by the discrete NK T subset of CD4+ cells in the periphery. Two hours after injection of IL-7 into mice, or after a 4-h exposure to IL-7 in vitro, IL-4 production by CD4+ cells in response to anti-TCR-alphabeta is markedly increased. In contrast, IFN-gamma production remains essentially unchanged. In beta2-microglobulin- and CD1-deficient mice, which lack NK T cells, IL-7 treatment does not reestablish normal levels of IL-4 by CD4+ T cells. Moreover, we observe that in wild-type mice, the memory phenotype (CD62L-CD44+) CD4+ T cells responsible for IL-4 production are not only NK1.1+ cells, but also NK1.1- cells. This NK1.1-IL-4-producing subset shares three important characteristics with NK T cells: 1) Vbeta8 skewing; 2) CD1 restriction as demonstrated by their absence in CD1-deficient mice and relative overexpression in MHC II null mice; 3) sensitivity to IL-7 in terms of IL-4 production. In conclusion, the present study provides evidence that CD4+MHC class I-like-dependent T cell populations include not only NK1.1+ cells, but also NK1.1- cells, and that these two subsets are biased toward IL-4 production by IL-7.