14. Immunologic rheumatic disorders

We provide the basics for the clinician who might be called on to consider the diagnosis of diseases such as systemic lupus erythematosus (SLE) or rheumatoid arthritis (RA) in their practice. We will emphasize clinical recognition and first-line laboratory testing. Only characteristics of the classic rheumatic inflammatory diseases, RA, SLE, Sjögren syndrome, scleroderma, and dermatomyositis/polymyositis, will be covered. In the past decade, RA is the only disease for which treatment has substantially improved. The treatment of RA has been revolutionized by the use of methotrexate and, more recently, tumor necrosis factor inhibitors. The goal of RA treatment today is to induce a complete remission as early as possible in the disease process, with the mantra being "elimination of synovitis equals elimination of joint destruction." The hope is that if the major mediators of Sjögren syndrome or SLE or scleroderma can be identified and then blocked, as in the example of tumor necrosis factor inhibitors in RA, more specific treatments will become available. Thus, RA has become an excellent model of this evolving paradigm. Through the identification of major mediators in its pathogenesis, novel and highly efficacious therapeutic agents have been developed.

[Role of L-type calcium channels in the calcium response and interleukin 4 (IL-4) synthesis by Th2 lymphocytes]]

CD4+ T lymphocytes are divided in Th1 cells that produce interferon (IFN) gamma and Th2 cells that synthesize IL-4. These subsets may arise from a common precursor: a combination of IL-12 plus anti-IL-4 monoclonal antibody (mAb) drives Th1 cell differentiation while IL-4 plus anti-IFN gamma mAb favor Th2 cell development. TCR stimulation activates protein kinase C that controls a calcium entry through L type calcium channels in Th2 cells. L type calcium channels are induced during Th2 but not Th1 cell differentiation. In addition, L type calcium channel inhibitors may be successfully used in the treatment of an experimental model of Th2 cell-mediated immunopathology. Thus, this signaling pathway that characterizes Th2 cells can be a target for the treatment of Th2 diseases.

Immunology at the crossroads. As decades of research have resulted in few clinical applications, it is time to think about new research strategies to understand the workings of the immune system

As decades of research have resulted in few clinical applications, it is time to think about new research strategies to understand the workings of the immune system

Apheresis of immune diseases and apheresis using immunological specificity

It has been clearly shown that autoimmune diseases can be treated by apheresis by eliminating immune complexes, however, the effects of therapeutic apheresis are not limited to immune disorders. Almost all diseases are associated with immune systems. Immune systems can be regulated by advanced techniques of apheresis, including immunoadsorption and immunocytapheresis, removing immune effector molecules and various immune-associated cells selectively. Therefore, apheresis can be used as a nondrug treatment for many diseases. In addition, disease-associated proteins that cause disease or are produced in the course of diseases and accumulate in the body could be eliminated selectively by apheresis using the extremely powerful ability of the immune system to recognize polypeptide structures specifically and distinguish miniscale differences among molecules. In this article, we discuss the current status of treatment of immune diseases by apheresis and possible treatment approach of a variety of diseases by apheresis based on immune reactions.

Macrophage activation syndrome

Macrophage activation syndrome (MAS) is a serious complication of childhood systemic inflammatory disorders that is thought to be caused by excessive activation and proliferation of T lymphocytes and macrophages. Recent findings in hemophagocytic lymphohistiocytosis, a disease that is clinically similar to MAS, highlight the possible pathogenetic role of a defective function of perforin, a protein involved in the cytolytic processes and control of lymphocyte proliferation. Although the clinical features of MAS have been well documented, early diagnosis can be difficult. Measurement of the serum ferritin level may assist in the diagnosis and may be a useful indicator of disease activity, therapy response, and prognosis. The recognition that MAS belongs to the secondary or reactive hemophagocytic syndromes has led to the proposal to rename it according to the contemporary classification of histiocytic disorders. Cyclosporin A has been found effective in patients with corticosteroid-resistant MAS. A recent report has suggested that etanercept may be a useful adjunctive therapeutic agent.

Complement-related diseases

This review article will consider some basic aspects of complement biology, address the clinical effects of hereditary complement deficiencies and the role of complement related to host cell entry, pathogenesis of infectious diseases, and apoptosis. The immunomodulation of autoimmune and inflammatory disorders related to complement components, the role of intravenous gamma-globulin and mechanisms of autoimmune urticaria and tolerance will be discussed briefly.

Fetal hematopoietic stem cell transplantation: a challenge for the twenty-first century

Successful in utero hematopoietic stem cell transplantation will likely represent a major step forward in the management of patients with congenital hematological, metabolic, and immunological disorders. We review the naturally occurring models of hematopoietic chimerism in animals and humans, as well as available experimental animal data and human clinical attempts of fetal transplantation. Data available from naturally occurring models and experimental models of fetal transplantation suggest that this technique should be translatable to the human fetus. However, to date, the success of human fetal hematopoietic stem cell therapy has been limited to fetuses with severe immunologic defects. Evaluation of successful attempts of human transplantation, the ontogeny of fetal immune development, and data available from animals provide insights into innovative approaches to fetal therapy that may bring the reality of successful fetal transplantation closer.

Soluble cytokine receptors in biological therapy

Due to their fundamental involvement in the pathogenesis of many diseases, cytokines constitute key targets for biotherapeutic approaches. The discovery that soluble forms of cytokine receptors are involved in the endogenous regulation of cytokine activity has prompted substantial interest in their potential application as immunotherapeutic agents. As such, soluble cytokine receptors have many advantages, including specificity, low immunogenicity and high affinity. Potential disadvantages, such as low avidity and short in vivo half-lifes, have been addressed by the use of genetically-designed receptors, hybrid proteins or chemical modifications. The ability of many soluble cytokine receptors to inhibit the binding and biological activity of their ligands makes them very specific cytokine antagonists. Several pharmaceutical companies have generated a number of therapeutic agents based on soluble cytokine receptors and many of them are undergoing clinical trials. The most advanced in terms of clinical development is etanercept (Enbrel, Immunex), a fusion protein between soluble TNF receptor Type II and the Fc region of human IgG1. This TNF-alpha; antagonist was the first soluble cytokine receptor to receive approval for use in humans. In general, most agents based on soluble cytokine receptors have been safe, well-tolerated and have shown only minor side effects in the majority of patients. Soluble cytokine receptors constitute a new generation of therapeutic agents with tremendous potential for applications in a wide variety of human diseases. Two current areas of research are the identification of their most promising applications and characterisation of their long-term effects.

Bone marrow transplantation for nonmalignant diseases

Bone marrow transplantation (BMT) has emerged as a major therapeutic option for a number of nonmalignant disorders affecting the bone marrow and leading to clinical manifestations most likely affecting distant organs. Disorders such as autoimmune diseases, metabolic disorders, hemoglobinopathies, immunodeficiencies, and others have been the target of high-dose therapy and autologous or allogeneic bone marrow, stem cell, or cord blood transplantation. Successful results have been reported in a large number of these disorders. In most instances the goal of transplantation is to provide sufficient degree of marrow engraftment to allow long-term amelioration of disease phenotype. For many of these disorders, early diagnosis is crucial in achieving the desired results as transplantation becomes difficult when significant end-organ damage sets in. Major unsolved problems, including toxicity of conditioning regimens, graft-versus-host disease, and donor availability, need to be addressed. We attempt to provide a comprehensive review of BMT and discuss unique features of this modality for treatment of nonmalignant disorders.

Allogeneic and autologous transplantation for haematological diseases, solid tumours and immune disorders: definitions and current practice in Europe

The Accreditation Sub-Committee of the EBMT regularly publishes special reports on current practice of haemopoietic stem cell transplantation for haematological diseases, solid tumours and immune disorders. Major changes have occurred since the last report in 1998. Haemopoietic stem cell transplantation today includes allogeneic and autologous stem cells derived from bone marrow, peripheral blood and cord blood. With reduced intensity conditioning regimens in allogeneic transplantation, the age limit has increased, permitting the inclusion of older patients. New indications have emerged, such as autoimmune disorders and AL amyloidosis for autologous, and solid tumours for allogeneic transplants. Other indications, such as autologous transplantation for breast cancer have been challenged. An updated report with revised tables and operating definitions is presented here.

Epitope spreading in immune-mediated diseases: implications for immunotherapy

Evidence continues to accumulate supporting the hypothesis that tissue damage during an immune response can lead to the priming of self-reactive T and/or B lymphocytes, regardless of the specificity of the initial insult. This review will focus primarily on epitope spreading at the T-cell level. Understanding the cellular and molecular basis of epitope spreading in various chronic immune-mediated human diseases and their animal models is crucial to understanding the pathogenesis of these diseases and to the ultimate goal of designing antigen-specific treatments.

Use of intravenous gamma globulins in neuroimmunologic diseases

Intravenous gamma globulin (IVIg) is used in the treatment of immunologic diseases that affect the entire neuroaxis, including the brain, spinal cord, peripheral nerves, muscles, and neuromuscular junction. The panel reviewed the available literature on the use of IVIg in order to evaluate the efficacy of this therapy in neuroimmunologic diseases. In prospective, rigorously controlled, double-blinded clinical trials, IVIg was found to have proven efficacy in the Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, multifocal motor neuropathy, dermatomyositis, and Lambert-Eaton myasthenic syndrome. It was found to be probably effective in myasthenia gravis and polymyositis, and possibly effective in several other neuroimmunologic diseases. Further studies are needed to evaluate the use of IVIg for neuroimmunologic diseases in which its efficacy is suspected but not proven and to elucidate its mechanisms of action.

Antibody-directed therapy: past, present, and future

Antibody-based therapy, which is the administration of polyclonal, hyperimmune, or monoclonal antibodies, has emerged as an important therapeutic approach in a wide variety of diseases. Polyclonal intravenous immunoglobulin became available in the early 1980s and supplanted intramuscular IgG in the treatment of antibody-deficiency diseases. During the last 2 decades, intravenous immunoglobulin has shown potent immunomodulatory and anti-inflammatory effects in many diseases. Whether these effects are mediated through specific antibody or Fc-receptor interactions is unclear. This review examines some of the current and future prospects for antibody-based therapy.

A less invasive treatment strategy to prevent intracranial hemorrhage in fetal and neonatal alloimmune thrombocytopenia

OBJECTIVE

The purpose of this study was to evaluate whether a less invasive treatment strategy results in a higher platelet count of the neonate and prevents intracranial hemorrhage in pregnant women who are at risk for fetal or neonatal alloimmune thrombocytopenia.

STUDY DESIGN

Between March 1989 and August 2000, 48 women with 56 pregnancies were treated. The population was divided into groups. A diagnostic fetal blood sample was taken in 7 cases that had a history of a sibling with an intracranial hemorrhage (group I; n = 8); treatment was provided, when necessary, with platelet transfusions and maternal administration of immunoglobulin. The other 48 cases, with a history of a sibling with severe thrombocytopenia but without intracranial hemorrhage, were retrospectively divided into group IIa (n = 16) and IIb (n = 32). In group IIa, at least 2 diagnostic fetal blood samples were taken, and when necessary, intrauterine platelet transfusion and immunoglobulin were administered (invasive treatment). In group IIb, no initial diagnostic fetal blood sampling was performed (noninvasive treatment). In 23 cases, immunoglobulin was administered, which was followed by predelivery fetal blood sampling in 8 cases. In 9 cases, only predelivery fetal blood sampling was performed, when necessary, followed by intrauterine platelet transfusion.

RESULTS

Results of our noninvasive treatment strategy were comparable to results of the invasive method in the prevention of intracranial hemorrhage (intracranial hemorrhage was not observed). In addition, there was an increasing trend in median platelet count and a lower number of cases with severe thrombocytopenia (<50 x 10(9)/L) in the noninvasive compared with the invasive treatment group (median platelet count, 92 and 31 x 10(9)/L, respectively).

CONCLUSION

Our results indicate that a less invasive treatment strategy in patients who are at risk for fetal or neonatal alloimmune thrombocytopenia and who have no history of a previous child who was affected with intracranial hemorrhage seems justified.

Etiology and outcome of hydrops fetalis

OBJECTIVES

To identify the etiology and pregnancy outcome of hydrops fetalis in a cohort of pregnancies referred to a tertiary maternal fetal medicine center in the UK. These data allow the review of a large series of pregnancies affected by hydrops fetalis and emphasize the importance of investigation and then treatment of individual cases. This provides parents with improved information and especially specific prognostic information.

METHODS

A retrospective review of 63 consecutive cases of hydrops fetalis managed between September 1996 and March 1999.

RESULTS

Of the pregnancies, 12.7% (n = 8) were associated with an 'immune' etiology. Of these, 62.5% (n = 5) had fetal anemia due to anti-D, 25% (n = 2) anti-Kell and 12.5% (n = 1) anti-c antibodies. The remaining 55 cases (87.3%) had a non-immune cause. Eight (14.5%) were due to human parvovirus B19 infection. Fourteen cases (25.5%) were associated with aneuploidy and, in four (7.3%), a primary hydrothorax was the cause of the non-immune hydrops fetalis. A cardiac cause was found in five (9.1%) cases. Three of these had supraventricular tachycardia and one had congenital complete heart block. Cystic hygroma was associated with hydrops fetalis in six cases. Twin-twin transfusion syndrome was the cause for hydrops in two cases. Massive transplacental hemorrhage was identified in one case. Fetal akinesia and muscular dystrophy caused hydrops in one case each. In 14.5% (8/55) of cases no obvious cause was identified and these were classified as 'idiopathic'. Three other cases could not be classified because parents declined investigations (unclassified). In the pregnancies with non-immune hydrops fetalis, the outcome was favorable in 27.3% (15/55) of cases.

CONCLUSION

The prognosis of hydrops fetalis differs markedly between different etiological groups. Etiologies range from treatable causes with a good outcome and probably no long-term side-effects (as in case of parvovirus B19), to others which are incompatible with life or are associated with considerable perinatal morbidity and mortality.

Transfusion reactions

Blood components are indicated in a wide variety of disease states. Although most transfusion therapies are administered uneventfully, there are a number of potential adverse transfusion reactions, some of which can assume serious dimensions. These reactions could occur during or even days after a transfusion. A brief description of the adverse effects of transfusion therapy has been outlined in this review. The etiopathogenesis, recognition and treatment of the adverse transfusion reactions have been highlighted. It is imperative that each transfusion of blood components has components be monitored carefully. Prompt recognition of an adverse event and early institution of remedial measures would help in decreasing transfusion related morbidity and mortality.