António Coutinho

Instituto Gulbenkian de Ciência (IGC) | IGC

IPEX is one of the few Inborn Errors of Immunity that may manifest in the fetal period, and its intrauterine forms certainly represent the earliest human autoimmune diseases. Here, we review the clinical, histopathologic, and genetic findings from 21 individuals in 11 unrelated families, with nine different mutations, described as cases of intraute...

Influence of cell density on the saturation of plasmocyte generation in vitro. Varying numbers of total splenic B cells were cultured for 7 days upon a monolayer of irradiated S17 feeder cells in the presence of CpG 1 μg/ml or LPS 20 μg/ml; at the end of the culture the supernatants were harvested for detection of secreted IgM.

FO B cells sorting gates. Single cell suspensions of splenic cells were prepared as described in Material and Methods and stained with mabs against B220, CD93, CD23, CD21. Sorting of FO B cells was done by first gating the lymphoid population on FCS/SSC dot plot, then gating on B220+CD93—cells and finally on CD21+CD23+ narrow gate within the core o...

The relative potency and quality of mouse B cell response to Toll-like receptors (TLRs) signaling varies significantly depending on the B cell subset and on the TLR member being engaged. Although it has been shown that marginal zone cells respond faster than follicular (FO) splenic B cells to TLR4 stimulus, FO B cells retain full capacity to prolif...

Sobre Ciência e o como fazer, aprendi tudo dos meus mestres, Göran Möller e Niels Jerne; aprendi exatamente as mesmas coisas duas vezes, para não me esquecer nunca mais. Com Tomaz Mota-Santos e Nelson Vaz, o meu caminho já é longo; e muito ganhei em sapiência e bondade com os repetidos exemplos queeles me deram. Bem hajam.

Haemoglobin S (HbS) is the gene known to confer the strongest advantage against malaria morbidity and mortality. Multiple HbS effects have been described resulting in protection against parasitaemia and reduction of severe malaria risk. This study aimed to explore HbS protection against severe malaria and Plasmodium falciparum parasitaemia in Angol...

Background Regulatory T cell (Treg) defects are associated with autoimmune diseases [1]. Immunoglobulin E (IgE) is elevated in primary immunodeficiencies associated to Regulatory T cell (Treg) defects [2] and is known to be positively correlated to disease activity in Systemic Lupus Erythematosus (SLE) [3,4]. More specifically, Treg frequency (incr...

Autoimmune disorders (AID) have been increasingly observed in association with primary immunodeficiencies (PIDs). Here, we discuss the interface between PID and AID, focusing on autoimmune manifestations early in life, which can be diagnostic clues for underlying PIDs. Inflammatory bowel disease in infants and children has been associated with IL-1...

Nitric oxide (NO) is a proposed component of malaria pathogenesis, and the inducible nitric oxide synthase gene (NOS2) has been associated to malaria susceptibility. We analyzed the role of NOS2 polymorphisms on NO bioavailability and on susceptibility to infection, Plasmodium carrier status and clinical malaria. Two distinct West African sample co...

Tolerance is a developmentally acquired property of the vertebrate immune system, in part ensured by regulatory CD4(+) lymphocytes (Treg cells) expressing the Foxp3 transcription factor. Recent work has shown that thymic emigrants are the preferential source of peripherally generated Treg cells. A new report in this issue of the European Journal of...

Development of cerebral malaria (CM), a severe and fatal form of clinical Plasmodium falciparum infection, results from a damaging cascade of vascular, inflammatory, and immunological host responses that leads to brain injury. Progression to CM can be modified by host genetic factors. Our case-control study in Angolan children aimed at highlighting...

Disease tolerance is a defense strategy that limits the fitness costs of infection irrespectively of pathogen burden. While restricting iron (Fe) availability to pathogens is perceived as a host defense strategy, the resulting tissue Fe overload can be cytotoxic and promote tissue damage to exacerbate disease severity. Examining this interplay duri...

The aim of this study was to assess the IgE serum levels in juvenile systemic lupus erythematosus patients and to evaluate possible associations with clinical and laboratory features, disease activity and tissue damage. The IgE serum concentrations in 69 consecutive juvenile systemic lupus erythematosus patients were determined by nephelometry. IgG...

The Down syndrome (DS) immune phenotype is characterized by thymus hypotrophy, higher propensity to organ-specific autoimmune disorders, and higher susceptibility to infections, among other features. Considering that AIRE (autoimmune regulator) is located on 21q22.3, we analyzed protein and gene expression in surgically removed thymuses from 14 DS...

To evaluate the frequency of primary immunodeficiencies (PID) in juvenile systemic lupus erythematosus (JSLE) patients. Some 72 JSLE patients were analyzed for levels of immunoglobulin classes and IgG subclasses and early components of the classical complement pathway. Determination of C4 gene copy number (GCN) and detection of type I C2 deficiency...

Genotyped single nucleotide polymorphisms. (0.08 MB DOC)

Cerebral malaria (CM) represents a severe outcome of the Plasmodium falciparum infection. Recent genetic studies have correlated human genes with severe malaria susceptibility, but there is little data on genetic variants that increase the risk of developing specific malaria clinical complications. Nevertheless, susceptibility to experimental CM in...

Corticosteroids are commonly used in the therapy of autoimmune disease (AID), although they are rarely, if ever, curative. This failure may result from their deleterious effects on regulatory T cells (Treg). In this work, we directly tested the effects of hydrocortisone (HC) administration on Treg number and function in established mouse models of...

Infection by Plasmodium, the causative agent of malaria, is associated with hemolysis and therefore with release of hemoglobin from RBC. Under inflammatory conditions, cell-free hemoglobin can be oxidized, releasing its heme prosthetic groups and producing deleterious free heme. Here we demonstrate that survival of a Plasmodium-infected host relies...

Early interactions between blood-stage Plasmodium parasites and cells of the innate immune system are very important in shaping the adaptive immune response to malaria, and a number of studies have suggested that DC are responsible for this phenomenon. Therefore, we examined the capacity of murine BM-derived DC to internalize parasites, be activate...

Natural IgM are involved in numerous immunological functions but the genetic factors that control the homeostasis of its secretion and upholding remain unknown. Prompted by the finding that C57BL/6 mice had significantly lower serum levels of IgM when compared with BALB/c mice, we performed a genome-wide screen and found that the level of serum IgM...

While BALB/c mice survive infection with blood stages of Plasmodium chabaudi chabaudi (AS), 70% of DBA/2 mice die by day 9-11 of infection, both strains controlling parasitaemia. We describe here that infection of DBA/2 mice results in extensive, multifocal hepatocyte death. Antibody neutralization of TNF-alpha prevents both liver damage and death.

Background Primary Immunodeficiencies (PIDs) represent unique opportunities to understand the operation of the human immune system. Accordingly, PIDs associated with autoimmune manifestations provide insights into the pathophysiology of autoimmunity as well as into the genetics of autoimmune diseases (AID). Epidemiological data show that there are...

The cause of autoimmune diseases remains unknown and, as a consequence, disease prediction and prophylaxis are not part of current clinical practice. Many autoimmune syndromes are accompanied by serological evidence of autoimmunity in the form of circulating auto-antibodies (AAb). As normal individuals produce large amounts of AAb, exploring the ma...

The recent progress in the genetic characterization of many primary immunodeficiencies (PIDs) allows for a better understanding of immune molecular and cellular mechanisms. The present chapter discusses associations between PIDs and autoimmune diseases (AIDs) in this new light. PIDs are classified according to the frequency of association with AIDs...

Primary immunodeficiency diseases (PIDs) represent a large and heterogeneous group of more than 120 different entities, most of which have now been genetically characterized (77). Increased susceptibility to infections is the predominant man- ifestation of almost all forms of PID, particularly in infants and children, demonstrating the paramount im...

LPS is a strong stimulator of the innate immune system and inducer of B lymphocyte activation. Two TLRs, TLR4 and RP105 (CD180), have been identified as mediators of LPS signaling in murine B cells, but little is known about genetic factors that are able to control LPS-induced cell activation. We performed a mouse genome-wide screen that aside from...

Natural T regulatory cells (NatTReg) limit immunopathology and protective immune responses induced upon microbial infection. In addition, infection increases the number and activity of NatTReg. These findings need to be conciliated with the process of 'self-nonself' discrimination based on the function of NatTReg committed intrathymically and posit...

Receptors encoded by the Vβ8 gene family detected by the monoclonal antibody F23.1 are expressed among ‘naturally’ activated T cells in normal spleen at frequencies significantly higher than in the total CD4+ and CD8+ cell populations. The positive selection of these clones into ‘natural’ T-cell activity could be the reason for the high frequencies...

The responsiveness of spleen cells from C3H/HeJ and C3H/Tif mice to lipopolysaccharide (LPS) was compared. Around 1,000-fold higher concentration of LPS were required to minimally activate HeJ cells, as compared with Tif high-responder cells, to both proliferation and polyclonal antibody secretion. However, HeJ cells did respond to higher LPS conce...

CD4+CD25+Foxp3+ regulatory T cells (Treg) are natural suppressors of autoimmunity but they can also dampen the effective clearance of infectious organisms. These cells have the potential to be exploited to prevent transplant rejection and to treat autoimmune disease. A paper in this issue of the European Journal of Immunology details a method to se...

The seminal work of Le Douarin and colleagues (Ohki et al. 1987; Ohki et al. 1988; Salaun et al. 1990; Coutinho et al. 1993) first demonstrated that peripheral tissue-specific tolerance is centrally established in the thymus, by epithelial stromal cells (TEC). Subsequent experiments have shown that TEC-tolerance is dominant and mediated by CD4 regu...

Ever since the foundations of Immunology, "self-tolerance" has remained a central issue in this field, pertaining to basic and clinical questions alike. Burnet and Medawar shared the Nobel Prize in 1960 for proposing that tolerance is induced by tissue antigens, if present during the development of the immune system during the embryonic/neonatal pe...

Maternal antibodies provide offspring with passive immunity and exert various active immunostimulatory functions, such as (i) antimicrobial protection through non-antigen-reactive antibodies, namely anti-idiotypes, (ii) allergen-specific suppression of IgE responsiveness and (iii) under pathological conditions, transfer of autoimmune diseases. As p...

The fundamental concepts of autopoiesis, which emphasize the circular organization underlying both living organisms and cognition, have been criticized on the grounds that since they are conceived as a tight logical chain of definitions and implications, it is often not clear whether they are indeed a scientific theory or rather just a potential sc...

Innate immunity, our inborn immediate defence mechanism, was thought for a long time to be non-specific and, consequently, research into innate mechanisms often took second place to research into adaptive immunity. In recent decades, however, the spotlight has shone on groundbreaking advances into mechanisms of innate immunity; from the hypothesis...

A recent paper on immunity and tolerance to antigenic determinants on antibody variable-regions (idiotypes) brings back to light the potential of idiotypic interactions among antibodies, B cells and T cells in the regulation of specific immune activities. The functional significance of idiotypic regulation has been established in a variety of syste...

Working with Francisco Varela has alwaysbeen extremely rewarding: his intelligence,excitement, humor, gentleness, but alsosolidity in the principles and the arguments,were all there. Perhaps most inspiring washis clarity in identifying the goal, often theessence of the problem at hand, and thepath to a solution. And certainly exemplaryin a scientis...

CD4+ regulatory T cells (Treg) play an indispensable role in tolerance to peripheral antigens, but the origin of the Treg pool in the adult remains unclear. Thus, while thymic commitment of Treg has been demonstrated, evidence also exists for the peripheral recruitment of naïve tissue-specific T cells into Treg functions. Anti-myelin basic protein...

Natural Abs (NAbs) are Igs present in the serum and body fluids of healthy vertebrate animals, without any previous intentional immunization. NAbs often exhibit autoreactivity but also play an essential role in immunity, being a first line of defense against infectious microorganisms. We have previously analyzed the natural serum IgM Ab repertoire...

CD25(+)4(+) regulatory T cells (T(reg)) play an indispensable role in preventing autoimmunity. Little is known, however, about the antigen specificities required for their development and effector functions. Mice transgenic for an anti-myelin basic protein (MBP) T cell antigen receptor (TCR) spontaneously develop experimental autoimmune encephalomy...

In nonobese diabetic (NOD) mice, the autoimmune attack of the beta-cells in pancreatic islets is now believed to result from abnormal thymic selection. Accordingly, grafts of thymic epithelium from NOD donors to athymic recipients promote autoimmune islet inflammation in normal strains, and intrathymic islet grafts decrease the incidence of disease...

Little progress has been achieved over the last 20 years on the clinical management of several conditions that relate to self-tolerance and to the regulation of immune responses: autoimmune diseases, transplantation tolerance, tumor immunity, allergy and vaccine development in chronic infections. These failures, it is argued, are due to the inabili...

The Instituto Gulbenkian de Ciencia and the Portugese Lupus Patients’ Association held the Second Gulbenkian Symposium on Natural Dominant Tolerance in Portugal on 2–5 November 2000.

The Xid mutation predominantly affects the development of B cells and consequently the levels and composition of natural antibodies in sera. In contrast to the congenic and susceptible BALB/c strain, immunodeficient BALB.Xid mice display a resistant phenotype both to acute Trypanosoma cruzi infection and to the development of severe cardiopathy. Be...

This chapter focuses on natural tolerance for the immunotherapy of cancer. Cancer cells, just like all other cells in the body, are tolerized by active, dominant mechanisms mediated by tissue-specific regulatory T cells, which suppress inflammatory or otherwise aggressive responses to the antigens they express, even if these are cancer-specific. It...

Lymphocyte polyclonal activation is a generalized mechanism of immune evasion among pathogens. In a mouse model of Trypanosoma cruzi infection (American trypanosomiasis), reduced levels of polyclonal lymphocyte responses correlate with resistance to infection and cardiopathy. We report here the characterization of a parasite protein with B-cell mit...

It is necessary to clarify principles and mechanisms of natural tolerance to body tissues, in order to derive appropriate diagnostics, therapeutics and prognostics of autoimmune diseases (AID). I will argue that AIDs result from deficits in autoreactive regulatory T cell generation and/or function, and propose a model that explains why relatively f...

Lewis rats develop experimental allergic encephalomyelitis (EAE) in response to immunization with myelin basic protein (MBP) in CFA, while Fischer rats are usually resistant. These strains, while comparably producing anti-MBP antibodies, also differ in their repertoire reactions to immunization, as measured by patterns of serum IgM reactivity with...

Multiple myeloma is accompanied by decreased polyclonal serum immunoglobulin concentrations. This suppression might be due to non-specific effects on the polyclonal lymphocyte populations as previously suggested, or it could include specific variable region-dependent mechanisms. Thus, differentiation, survival and activation to Ig secretion of B-li...

In normal animals, responses to immunization include alterations in the serum IgM antibody repertoire, as scored on autologous tissue antigens with no respect for the immunizing antigen. These immunogen-nonspecific antibody reactions were found previously to display specific structures dependent on strain and immunization protocols. Using major his...

Locally produced type I interferon (IFN-I) enhances the sensitivity of bone marrow B cell to IgM receptor ligation. The establishment of B cell repertoires, on the other hand, seems to involve selective processes that are critically dependent on B cell receptor (BCR) ligation. In order to assess the importance of BCR triggering thresholds on the se...

Self reactive T and B cells are present in healthy individuals. Thus, activation and expansion of autoreactive cells in autoimmune disease may result either from the stimulation of the immune system by a self antigen that acquired immunogenic properties or from defective regulation of mechanisms that normally control autoreactivity. Most autoimmune...

The electrical behavior and the electroluminescence (EL) obtained from n- and p-type ITO/porous silicon LEDs have been characterized simultaneously at different temperatures. Stability and aging in air were investigated, and means for avoiding their detrimental effects in the experiments are suggested. The dominating current carrying mechanism resp...

Immunization of Lewis rats with myelin basic protein (MBP) in complete Freud's adjuvant (CFA) provokes experimental allergic encephalomyelitis (EAE). Here we compare, irrespective of antigen specificity, the structure and dynamics of serum IgM autoreactive repertoires following immunization with MBP/CFA in EAE-susceptible Lewis and relatively resis...

Immunization of Lewis rats with myelin basic protein (MBP) in complete Freud's adjuvant (CFA) provokes experimental allergic encephalomyelitis (EAE). Here we compare, irrespective of antigen specificity, the structure and dynamics of serum IgM autoreactive repertoires following immunization with MBP/CFA in EAE-susceptible Lewis and relatively resis...

Antibodies that are present in the serum of healthy individuals in the absence of deliberate immunization with any antigen, are refered to as natural antibodies. A vast majority of natural antibodies react with one or more self antigens and are termed as natural autoantibodies. The importance of natural autoantibodies in immune regulation has long...

Most T cells in a normal non-immunized individual are in a resting state. However, a small proportion of splenic T cells are large activated cells both in specific pathogen-free and antigen-free mice. To further elucidate the effector functions associated with these "naturally" activated CD4+ T cells, we have characterized the expression of various...

The present experiments address functional antibody diversity and clonal distribution in murine available repertoires. IgM-containing supernatants were prepared by unbiased, polyclonal stimulation of resting splenic B cells from C57BL/6 mice, to ensure similar numbers of responding clones/culture and equivalent growth and maturation of all clones....

Global analysis of natural antibody repertoires has revealed a marked conservation of reactivity patterns within inbred mouse strains, and characteristic strain-specific differences. We have now analyzed the genetic control of reactivity repertoires, aiming at identifying the respective selection mechanisms. Multiparametric statistics of a large nu...

Lipopolysaccharide (LPS) from gramnegative bacteria is a well-known T cell-independent B lymphocyte mitogen and macrophage/monocyte activator. While the conventional view holds that LPS is ignored by T cells, we report here that administration of LPS to mice activates all B cells, but also engages most CD4 and CD8 T cells, as measured by the expres...

Compartmentation of B lymphocyte populations is associated with differences in both development stage and sensitivity to Ig (sIg)-dependent triggering. In order to characterize the factors that contribute in setting the level of sensitivity of a B cell, we quantified sIgM-dependent regulation of Ig secretion in purified mature and immature B cells...

Spleen and bone marrow cells from normal or Rag-1-deficient donors are equally competent in their ability to induce neonatal transplantation tolerance in semi-allogeneic hosts, and the latter are also capable of tolerizing fully allogeneic recipients. Both types of donor cells resulted in comparable levels of haemopoietic chimerism in tolerant anim...

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We have evaluated the impact of transgenic immunoglobulin (TGIg) expression on endogenous antibody repertoires. The transgenic system was chosen as to allow for normal recombination of endogenous Ig genes, secretion of TGIg from early development on, and distinguishing the TGIg from endogenous Ig by several serological markers on the C and V region...

Antigen-free (AGF) and germ-free (GF) mice, although essentially free of serum IgG, maintain normal levels of circulating IgM. Using a quantitative immunoblot assay, we have now analyzed the repertoire of serum IgM from AGF, GF, and specific pathogen-free (SPF) BALB/c mice, on large panels of natural antigens from homologous tissues and bacteria. T...