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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A boy of Caucasian origin with a new subtype of autoimmune lymphoproliferative syndrome (ALPS) is described. The clinical picture was dominated by chronic noninfectious lymphadenopathy, splenomegaly, and recurrent bacterial infections. At the age of 6 the patient died of pneumococcal meningitis. Laboratory investigation disclosed impaired apoptosis in both B- and T-lymphocyte subsets and expanded populations of CD3+CD4-CD8- T lymphocytes. Furthermore, marked dysregulation of humoral immune responses with transient expansion of monoclonal B cells, corresponding monoclonal gammopathy, and the presence of autoantibodies was found. Functional and molecular analysis revealed that Fas protein expression was normal, a mutation in the Fas gene was not found. Moreover, transcription of the downstream effector caspase-10 was unremarkable. This patient is unique compared to previously described patients as severe humoral immunodeficiency and monoclonal gammopathy are usually not described in patients with ALPS. This case points out the important role of apoptosis in regulating the degree of humoral immune responses at a clonal level in humans and gives further evidence for the phenotypic diversity of ALPS.
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PMID:Autoimmune lymphoproliferative syndrome associated with severe humoral immunodeficiency and monoclonal gammopathy. 1210 64

Apoptosis is a form of programmed cell death that is controlled by aspartate-specific cysteine proteases called caspases. In the immune system, apoptosis counters the proliferation of lymphocytes to achieve a homeostatic balance, which allows potent responses to pathogens but avoids autoimmunity. The CD95 (Fas, Apo-1) receptor triggers lymphocyte apoptosis by recruiting Fas-associated death domain (FADD), caspase-8 and caspase-10 proteins into a death-inducing signalling complex. Heterozygous mutations in CD95, CD95 ligand or caspase-10 underlie most cases of autoimmune lymphoproliferative syndrome (ALPS), a human disorder that is characterized by defective lymphocyte apoptosis, lymphadenopathy, splenomegaly and autoimmunity. Mutations in caspase-8 have not been described in ALPS, and homozygous caspase-8 deficiency causes embryonic lethality in mice. Here we describe a human kindred with an inherited genetic deficiency of caspase-8. Homozygous individuals manifest defective lymphocyte apoptosis and homeostasis but, unlike individuals affected with ALPS, also have defects in their activation of T lymphocytes, B lymphocytes and natural killer cells, which leads to immunodeficiency. Thus, caspase-8 deficiency in humans is compatible with normal development and shows that caspase-8 has a postnatal role in immune activation of naive lymphocytes.
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PMID:Pleiotropic defects in lymphocyte activation caused by caspase-8 mutations lead to human immunodeficiency. 1235 64

Lymphocyte homeostasis is achieved by a balance between the production and death of lymphocytes. In particular, T lymphocytes differentiate and mature in the thymus and are released into the peripheral circulation, where they can travel to sites of encounter with antigen. Once in the circulation, T lymphocytes have varying life spans depending on whether they remain resting, become activated by antigen and replicate, or they become memory cells. The regulation of lymphocyte fate, especially the induction of programmed cell death, or apoptosis, has become a focus of intense molecular research, and much has been learned. In particular, the Fas receptor and other members of the tumor necrosis factor receptors, as well as their respective ligands, have emerged as key regulators of T lymphocyte apoptosis. We are studying genetic abnormalities of this death pathway, which we have found to underlie the human disease, autoimmune lymphoproliferative syndrome (ALPS). The study of ALPS has revealed that inhibiting the death of lymphocytes can lead to autoimmune consequences. Also, the homeostasis of T lymphocytes can be powerfully affected by viruses and other infectious agents. In particular, the human immunodeficiency virus can cause the attrition of CD4+ T lymphocytes by inducing the premature death of such cells. We are studying the molecular mechanism by which the HIV causes CD4+ T cell destruction.
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PMID:Molecular regulation of T lymphocyte homeostasis in the healthy and diseased immune system. 1285 83

In the immune system, lymphocyte activation by antigen is followed by cell proliferation and induction of effector functions. Subsequently, physiologic cell-death signals are induced, resulting in removal of expanded effector-cell populations, to maintain homeostasis. Caspases are intracellular participants in both activation responses and cell death by apoptosis. Targets of caspases include inflammatory activators and also other members of the caspase family that mediate apoptosis. Caspase-8 and caspase-10 participate in the protease cascade following cell surface CD95 engagement by its ligand. Humans with defects in these caspases were initially evaluated for the autoimmune lymphoproliferative syndrome because of their spleen and lymph node enlargement. Although both caspase-8- and caspase-10-deficient individuals had impaired apoptosis, those with caspase-8 deficiency, who also had immunodeficiency, had additional defects in activation of lymphocytes and natural killer cells. These disorders help to define the importance and specificity of the caspase proteases in intracellular signaling pathways.
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PMID:Immune disorders caused by defects in the caspase cascade. 1290 72

Caspase-8 is best known for its cell death function via death receptors. Recent evidence indicates that caspase-8 also has nonapoptotic functions. Caspase-8 deficiency is associated with pathologies that are unexpected for a proapoptotic molecule, such as abrogation of activation-induced lymphocyte proliferation, perturbed immune homeostasis, and immunodeficiency. In this study, we report the long-term physiological consequences of T cell-specific deletion of caspase-8 (tcasp8-/-). We show that tcasp8-/- mice develop an age-dependent lethal lymphoproliferative and lymphoinfiltrative immune disorder characterized by lymphoadenopathy, splenomegaly, and accumulation of T cell infiltrates in the lungs, liver, and kidneys. Peripheral casp8-/- T cells manifest activation marker up-regulation and are proliferating in the absence of any infection or stimulation. We also provide evidence suggesting that this immune disorder is different from the autoimmune lymphoproliferative syndrome. Interestingly, the condition described in tcasp8-/- mice manifests features consistent with the disorder described in humans with Caspase-8 deficiency. These findings suggest that tcasp8-/- mice may serve as an animal model to evaluate Caspase-8-deficient patient prognosis and therapy. Overall, our study uncovers novel in vivo functions for caspase-8 in immune regulation.
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PMID:Caspase-8 deficiency in T cells leads to a lethal lymphoinfiltrative immune disorder. 1615 84

Autoimmune lymphoproliferative disorders, including autoimmune lymphoproliferative syndrome (ALPS) and Dianzani autoimmune lymphoproliferative disease (DALD), are inherited defects of the Fas apoptotic pathway characterized by lymphoid accumulation and autoimmune manifestations. We report the molecular, clinical, immunologic features and the long-term progress of 31 patients. Four carried Fas gene mutations and one also displayed a caspase 10 polymorphism that probably contributed to the phenotype. Seven patients developed antibody deficiency and their clinical pictures overlapped those of subjects with common variable immunodeficiency (CVID). We postulate the existence of a disorder that involves the Fas pathway and displays the characteristics of both autoimmune lymphoproliferative disease and CVID.
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PMID:The broad spectrum of autoimmune lymphoproliferative disease: molecular bases, clinical features and long-term follow-up in 31 patients. 1653 20

Epstein-Barr virus (EBV) is a ubiquitous human gamma-herpesvirus that infects about 95% of the adult population. The majority of primary infections occurs in early childhood and is generally subclinical; it can cause infectious mononucleosis (IM), which is usually a self-limiting lymphoproliferative disorder. However, infection of EBV occasionally results in severe, often lethal diseases, which include fatal IM, hemophagocytic syndrome, polyclonal lymphoproliferative disorders, and malignant lymphoma. These severe EBV-related illnesses occur secondary to some primary immunodeficiency diseases showing inefficient immune reaction to EBV. One example is X-linked lymphoproliferative disease (XLP), which is caused by mutations in the SLAM-associated protein (SAP) gene. The major clinical manifestations of XLP are fulminant IM, malignant lymphoma and dysgammaglobulinemia. Aplastic anemia, virus-associated hemophagocytic syndrome, and vasculitis have also been reported in XLP. We have developed a flow cytometric method using the anti-SAP monoclonal antibody to search for XLP. This clinically useful assay has successfully been used to identify XLP patients in Japan. In this review, clinical and mutational characteristics of XLP in Japan are mainly described. In addition, it is shown that the similar situations to XLP can occur in other primary immunodeficiencies involving T-cell killing function, such as autoimmune lymphoproliferative syndrome caused by Fas gene mutations or familial hemophagocytic lymphohistiocytosis caused by perforin gene mutations. Finally, the EBV-related terrible disease condition, namely chronic active EBV infection, which is common in Asian areas but its genetic background remains to be elucidated, will be touched on.
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PMID:Primary Immunodeficiencies Inducing EBV-Associated Severe Illnesses. 1730 92

Autoimmune cytopenias are well recognised in patients with primary immune deficiency, but treatment may be difficult. We report eight children with autoimmune cytopenias (autoimmune haemolytic anaemia, autoimmune thrombocytopenia, autoimmune neutropenia) complicating immune deficiency states (common variable immunodeficiency, Wiskott-Aldrich Syndrome, autoimmune lymphoproliferative syndrome, combined immunodeficiency) treated with between 1 and 3 courses of rituximab (anti-CD20). Responses occurred for 90% of treatments but relapse rates (after a median of 53 weeks) were high (78%). We conclude that rituximab is an effective treatment for autoimmune cytopenias in children with immune deficiencies, but repeated courses of treatment may be needed.
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PMID:Rituximab for the treatment of autoimmune cytopenias in children with immune deficiency. 1749 97

A number of primary immunodeficiency diseases represent a paradox of immunodeficiency and autoimmunity. In this minireview, we present basic concepts of apoptosis and disorder of apoptosis as one of the mechanisms to explain such a paradox between immunodeficiency and autoimmunity, which is exemplified by autoimmune lymphoproliferative syndrome (ALPS).
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PMID:Disorders of apoptosis: mechanisms for autoimmunity in primary immunodeficiency diseases. 1819 40

Programmed cell death is important for maintaining lymphocyte homeostasis. Several human-inherited diseases with impaired apoptosis have been identified at the genetic level: autoimmune lymphoproliferative syndrome, caspase-8 deficiency state, and X-linked lymphoproliferative syndrome. These diseases feature excess lymphocyte accumulation, autoimmunity, or immunodeficiency. Elucidating their molecular pathogenesis has also provided new insights into the signaling mechanisms regulating apoptosis and lymphocyte activation.
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PMID:Genetic defects of apoptosis and primary immunodeficiency. 1842 36


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