Increases in circulating and lymphoid tissue interleukin-10 in autoimmune lymphoproliferative syndrome are associated with disease expression

Autoimmune lymphoproliferative syndrome (ALPS) is an inherited disorder in which genetic defects in proteins that mediate lymphocyte apoptosis, most often Fas, are associated with enlargement of lymph nodes and the spleen and a variety of autoimmune manifestations. Some patients with ALPS have relatives with these same apoptotic defects, however, who are clinically well. This study showed that the circulating levels of interleukin 10 (IL-10) were significantly higher (P <.001) in 21 patients with ALPS than in healthy controls. Moreover, the peripheral blood mononuclear cells (PBMCs) and lymphoid tissues of these patients with ALPS contained significantly higher levels of IL-10 messenger RNA (mRNA; P <.001 and P <.01, respectively). By fractionating PBMC populations, disproportionately high concentrations of IL-10 mRNA were found in the CD4(-)CD8(-) T-cell population, expansion of which is virtually pathognomonic for ALPS. Immunohistochemical staining showed intense IL-10 protein signals in lymph node regions known to contain CD4(-)CD8(-) T cells. Nonetheless, in vitro studies showed no influence of IL-10 on the survival of CD4(-)CD8(-) T cells. Overexpression of IL-10 in patients with inherited apoptotic defects is strongly associated with the overt manifestations of ALPS.     

Variations of the perforin gene in patients with autoimmunity/lymphoproliferation and defective Fas function

Mutations decreasing function of the Fas death receptor cause the autoimmune lymphoproliferative syndrome (ALPS) with autoimmune manifestations, spleen/lymph node enlargement, and expansion of CD4/CD8-negative T cells. Dianzani Autoimmune Lymphoproliferative Disease (DALD) is a variant lacking this expansion. Perforin is involved in cell-mediated cytotoxicity and its biallelic mutations cause familial hemophagocytic lymphohistiocytosis (HLH). We previously described an ALPS patient carrying heterozygous mutations of the Fas and perforin genes and suggested that they concurred in ALPS. This work extends the analysis to 14 ALPS, 28 DALD, and 816 controls, and detects an N252S amino acid substitution in 2 ALPS, and an A91V amino acid substitution in 6 DALD. N252S conferred an OR = 62.7 (P = .0016) for ALPS and A91V conferred an OR = 3 (P = .016) for DALD. Copresence of A91V and variations of the osteopontin gene previously associated with DALD conferred an OR = 17 (P = .0007) for DALD. In one N252S patient, NK activity was strikingly defective in early childhood, but became normal in late childhood. A91V patients displayed lower NK activity than controls. These data suggest that perforin variations are a susceptibility factor for ALPS/DALD development in subjects with defective Fas function and may influence disease expression.     

Immunophenotypic profiles in families with autoimmune lymphoproliferative syndrome

Autoimmune lymphoproliferative syndrome (ALPS) type Ia is caused by inherited defects in apoptosis and is characterized by nonmalignant lymphoaccumulation, autoimmunity, and increased alpha/beta(+) double-negative T cells (alpha/beta(+)-DNT cells). This study reports immunophenotypic findings in 166 members of 31 families with ALPS type Ia, associated with genetic mutations in the TNFRSF6 gene encoding Fas. The ALPS type Ia probands (n = 31) and relatives having both a Fas mutation and clinically proven ALPS (n = 28) showed significant expansion of CD8(+) T cells, alpha/beta(+)-DNT cells, gamma/delta(+)-DNT cells, CD3(+)/ HLA-DR(+) T cells, CD8(+)/CD57(+) T cells, and CD5(+) B cells. Relatives with Fas mutations, but without all the required criteria for ALPS (n = 42), had expansions of CD8(+) T cells, alpha/beta(+)-DNT cells, and gamma/delta(+)-DNT cells. Interestingly, relatives without a Fas mutation and with no features of ALPS (n = 65) demonstrated a small but significant expansion of CD8(+) T cells, both DNT cell subsets, and CD5(+) B cells. As compared to unrelated healthy controls, lymphocyte subset alterations were greatest in the probands, followed by the relatives with mutations and ALPS. Probands and relatives with mutations and ALPS also showed a lower number of CD4(+)/CD25(+) T cells that, in combination with an independent increase in HLA-DR(+) T cells, provided a profile predictive of the presence of clinical ALPS. Because quantitative defects in apoptosis were similar in mutation-positive relatives regardless of the presence of clinical ALPS, factors, other than modifiers of the Fas apoptosis pathway, leading to these distinctive immunophenotypic profiles most likely contribute to disease penetrance in ALPS.     

Identification of new Fas mutations in a patient with autoimmune lymphoproliferative syndrome (ALPS) and eosinophilia

Autoimmune lymphoproliferative syndrome (ALPS) is a rare, newly recognized, chronic lymphoproliferative disorder in children and is characterized by lymphadenopathy, splenomegaly, pancytopenia, autoimmune phenomena and expansion of double-negative (DN) T lymphocytes (TCR alpha beta+, CD4-, CD8-). Defective lymphocyte apoptosis caused by mutations of the Fas (CD95) gene has been linked in the pathogenesis of ALPS, as binding of Fas-ligand to Fas can trigger apoptosis. Of the ALPS cases reported to date, point mutations, frameshifts and silent mutations in Fas all have been identified. We report two new point mutations in Fas in a child with ALPS and eosinophilia; studies on other family members established the pattern of inheritance for these mutations. Flow cytometric analysis of blood and tissues (spleen, lymph node, bone marrow) revealed abnormally expanded populations of DN T lymphocytes. Furthermore, activated lymphocytes and IFN gamma-activated eosinophils were resistant to Fas-mediated apoptosis. Eosinophil resistance to Fas-mediated apoptosis has not been previously described in ALPS. Sequencing of Fas revealed two separate mutations not previously reported. One mutation, a C to T change at base 836, was a silent mutation inherited from the mother, while the second mutation, a C to A change at base 916, caused a non-conservative amino acid substitution in the death domain of Fas, changing a threonine to a lysine. This mutation is associated with a predicted change in the structure of a part of the death domain from a beta-pleated sheet to an alpha-helix. We speculate that the mutation in the death domain prevents the interaction of Fas with intracellular mediators of apoptosis and is responsible for the autoimmune manifestations of ALPS and the abnormal lymphocytosis and eosinophilia in this patient.     

Dominant expression of interleukin 10 but not interferon gamma in CD4(-)CD8(-)alphabetaT cells of autoimmune lymphoproliferative syndrome

Cytokine expression in CD4-CD8- double-negative (DN) T cells of autoimmune lymphoproliferative syndrome (ALPS) was analysed. Two patients with DN alphabetaT-cell expansion showed higher serum interleukin 10 (IL-10) levels than one patient without it. Intracellular flow-cytometric analysis indicated the IL-10-expressing CD3+CD4-CD8- cells in patients with lymphoproliferation. Quantitative real-time polymerase chain reaction revealed approximately 100 times higher IL-10, but not interferon-gamma or transforming growth factor-beta in DN than in single-positive T cells. IL-10 was exclusively expressed in DN alphabeta but not (gamma)(delta)T cells. Circulating DN alphabetaT cells may constitutively express IL-10 and contribute to the ALPS phenotype.     

Identification of New Fas Mutations in a Patient with Autoimmune Lymphoproliferative Syndrome (ALPS) and Eosinophilia

ABSTRACT: Autoimmune lymphoproliferative syndrome (ALPS) is a rare, newly recognized, chronic lymphoproliferative disorder in children and is characterized by lymphadenopathy, splenomegaly, pancytopenia, autoimmune phenomena and expansion of double-negative (DN) T lymphocytes (TCRαβ⁺, CD4⁻, CD8⁻). Defective lymphocyte apoptosis caused by mutations of the Fas (CD95) gene has been linked in the pathogenesis of ALPS, as binding of Fas-ligand to Fas can trigger apoptosis. Of the ALPS cases reported to date, point mutations, frameshifts and silent mutations in Fas all have been identified. We report two new point mutations in Fas in a child with ALPS and eosinophilia; studies on other family members established the pattern of inheritance for these mutations. Flow cytometric analysis of blood and tissues (spleen, lymph node, bone marrow) revealed abnormally expanded populations of DN T lymphocytes. Furthermore, activated lymphocytes and IFNγ-activated eosinophils were resistant to Fas-mediated apoptosis. Eosinophil resistance to Fas-mediated apoptosis has not been previously described in ALPS. Sequencing of Fas revealed two separate mutations not previously reported. One mutation, a C to T change at base 836, was a silent mutation inherited from the mother, while the second mutation, a C to A change at base 916, caused a non-conservative amino acid substitution in the death domain of Fas, changing a threonine to a lysine. This mutation is associated with a predicted change in the structure of a part of the death domain from a β-pleated sheet to an α-helix. We speculate that the mutation in the death domain prevents the interaction of Fas with intracellular mediators of apoptosis and is responsible for the autoimmune manifestations of ALPS and the abnormal lymphocytosis and eosinophilia in this patient.     

An inherited disorder of lymphocyte apoptosis: the autoimmune lymphoproliferative syndrome

The autoimmune lymphoproliferative syndrome (ALPS) affords novel insights into the mechanisms that regulate lymphocyte homeostasis and underlie the development of autoimmunity. This syndrome arises early in childhood in persons who inherit mutations in genes that mediate apoptosis, or programmed cell death. The timely deletion of lymphocytes is a way to prevent their accumulation and the persistence of cells that can react against the body's own antigens. In ALPS, defective lymphocyte apoptosis permits chronic, nonmalignant adenopathy and splenomegaly; the survival of normally uncommon "double-negative" CD3+ CD4- CD8- T cells; and the development of autoimmune disease. Most cases of ALPS involve heterozygous mutations in the lymphocyte surface protein Fas that impair a major apoptotic pathway. Detailed immunologic investigations of the cellular and cytokine profiles in ALPS show a prominent skewing toward a T-helper 2 phenotype; this provides a rational explanation for the humoral autoimmunity typical of patients with ALPS. Prospective evaluations of 26 patients and their families show an ever-expanding spectrum of ALPS and its major complications: hypersplenism, autoimmune hemolytic anemia, thrombocytopenia, and neutropenia. Defective apoptosis may also contribute to a heightened risk for lymphoma.     

A genetic disorder of lymphocyte apoptosis involving the fas pathway: The autoimmune lymphoproliferative syndrome

Autoimmune lymphoproliferative syndrome (ALPS) is a recently characterized human disorder that typically presents with lymphocyte accumulation in the first few years of life. This is often associated with the development of autoimmunity, most commonly affecting the hematopoietic system. A key laboratory feature is the marked expansion of double-negative (CD4- and CD8-) T cells that express the a/b T-cell receptor. ALPS is associated with defective Fas-mediated lymphocyte apoptosis, and in most patients, this results from a heterozygous mutation in the TNFRSF6 gene encoding Fas. The clinical features of ALPS reveal the importance of the Fas apoptotic pathway in maintaining lymphocyte homeostasis and protecting against autoimmunity and lymphoid malignancy.     

Perforin-dependent apoptosis functionally compensates Fas deficiency in activation-induced cell death of human T lymphocytes

Activation-induced cell death (AICD) is involved in peripheral tolerance by controlling the expansion of repeatedly stimulated T cells via an apoptotic Fas (CD95; APO-1)-dependent pathway. The TNFRSF-6 gene encoding Fas is mutated in children suffering from autoimmune lymphoproliferative syndrome (ALPS), which is characterized by lymphoproliferation and autoimmunity. We examined AICD in Fas-deficient T cells from ALPS patients. We showed that primary activated Fas-deficient T cells die by apoptosis after repeated T cell antigen receptor (TCR) stimulation despite resistance to Fas-mediated cell death. This Fas-independent AICD was found to be mediated through a cytotoxic granules-dependent pathway. Cytotoxic granules-mediated AICD was also detected in normal T lymphocytes though to a lesser extent. As expected, the cytotoxic granules-dependent AICD was abolished in T cells from Rab27a- or perforin-deficient patients who exhibited defective granules-dependent cytotoxicity. Supporting an in vivo relevance of the cytotoxic granules-dependent AICD in ALPS patients, we detected an increased number of circulating T lymphocytes expressing granzymes A and B. Altogether, these data indicated that the cytotoxic granules-dependent cell death in ALPS may compensate for Fas deficiency in T lymphocytes. Furthermore, they identified a novel AICD pathway as a unique alternative to Fas apoptosis in human peripheral T lymphocytes.     

The development of lymphomas in families with autoimmune lymphoproliferative syndrome with germline Fas mutations and defective lymphocyte apoptosis.

Lymphomas were studied in kindreds with autoimmune lymphoproliferative syndrome (ALPS; Canale-Smith syndrome), a disorder of lymphocyte homeostasis usually associated with germline Fas mutations. Fas (CD95/APO-1) is a cell surface receptor that initiates programmed cell death, or apoptosis, of activated lymphocytes. Lymphoma phenotype was determined by immunohistochemistry, frequency of CD3(+)CD4(-)CD8(-) T-cell-receptor alpha/beta cells by flow cytometry, nucleotide sequences of the gene encoding Fas (APT1, TNFRSF6), and the percentage of lymphocytes undergoing apoptosis in vitro. Of 223 members of 39 families, 130 individuals possessed heterozygous germline Fas mutations. Eleven B-cell and T-cell lymphomas of diverse types developed in 10 individuals with mutations in 8 families, up to 48 years after lymphoproliferation was first documented. Their risk of non-Hodgkin and Hodgkin lymphomas, respectively, was 14 and 51 times greater than expected (each P <.001). Investigation of these 10 patients and their relatives with Fas mutations revealed that all had defective lymphocyte apoptosis and most had other features of ALPS. The tumor cells retained the heterozygous Fas mutations found in the peripheral blood and manifested defective Fas-mediated killing. These data implicate a role for Fas-mediated apoptosis in preventing B-cell and T-cell lymphomas. Inherited defects in receptor-mediated lymphocyte apoptosis represent a newly appreciated risk factor for lymphomas.     

Dyserythropoiesis associated with a fas-deficient condition in childhood

Defective lymphocyte apoptosis caused by mutations of the Fas gene can result in an autoimmune lymphoproliferative syndrome (ALPS) in humans. We report two cases of dyserythropoiesis associated with a Fas-deficient condition in childhood. In both cases, dyserythropoiesis predominated on the more mature erythroblasts, and was associated with a lymphoproliferative syndrome as well as with haemolytic anaemia, hypergammaglobulinaemia and the expansion of an unusual population of CD4- CD8- T cells that express the alpha/beta T-cell receptor. The regression of dyserythropoiesis under steroid therapy suggested that it resulted from an autoimmune mechanism, itself secondary to the lymphocyte Fas apoptosis deficiency. Fas-defective apoptosis may be a new aetiology for childhood dyserythropoiesis.     

Pyrimethamine treatment does not ameliorate lymphoproliferation or autoimmune disease in MRL/lpr-/- mice or in patients with autoimmune lymphoproliferative syndrome

Autoimmune lymphoproliferative syndrome (ALPS) is an inherited disorder of lymphocyte apoptosis leading to childhood onset of marked lymphadenopathy, hepatosplenomegaly, autoimmune cytopenias, and increased risk of lymphoma. Most cases are associated with heterozygous mutations in the gene encoding Fas protein. Prolonged use of immunosuppressive drugs that do ameliorate its autoimmune complications fail to consistently lessen lymphoproliferation in ALPS. A case series had described children with ALPS, whose spleens (SPL) and lymph nodes decreased in size when treated weekly with pyrimethamine and sulfadoxine; parallel in vitro studies showed only pyrimethamine to promote apoptosis. On the basis of that experience, we undertook additional in vitro lymphocyte apoptosis assays, and measured SPL weights, lymphocyte numbers, and immunophenotypes in Fas-deficient MRL/lpr-/- mice to gain further insights into the utility of combined pyrimethamine/sulfadoxine or pyrimethamine alone. Moreover, seven children with ALPS enrolled in a study of escalating dose of pyrimethamine alone given twice weekly for 12 weeks to determine if their lymphadenopathy and/or splenomegaly would diminish, as assessed by standardized computerized tomography. Neither pyrimethamine alone or with sulfadoxine in the MRL/lpr-/- mice, nor pyrimethamine alone in ALPS patients proved efficacious. We conclude that these drugs do not warrant further use empirically or as part of clinical trials in ALPS Type Ia as a lympholytic agent.     

NRAS mutation causes a human autoimmune lymphoproliferative syndrome

The p21 RAS subfamily of small GTPases, including KRAS, HRAS, and NRAS, regulates cell proliferation, cytoskeletal organization, and other signaling networks, and is the most frequent target of activating mutations in cancer. Activating germline mutations of KRAS and HRAS cause severe developmental abnormalities leading to Noonan, cardio-facial-cutaneous, and Costello syndrome, but activating germline mutations of NRAS have not been reported. Autoimmune lymphoproliferative syndrome (ALPS) is the most common genetic disease of lymphocyte apoptosis and causes autoimmunity as well as excessive lymphocyte accumulation, particularly of CD4(-), CD8(-) alphabeta T cells. Mutations in ALPS typically affect CD95 (Fas/APO-1)-mediated apoptosis, one of the extrinsic death pathways involving TNF receptor superfamily proteins, but certain ALPS individuals have no such mutations. We show here that the salient features of ALPS as well as a predisposition to hematological malignancies can be caused by a heterozygous germline Gly13Asp activating mutation of the NRAS oncogene that does not impair CD95-mediated apoptosis. The increase in active, GTP-bound NRAS augments RAF/MEK/ERK signaling, which markedly decreases the proapoptotic protein BIM and attenuates intrinsic, nonreceptor-mediated mitochondrial apoptosis. Thus, germline activating mutations in NRAS differ from other p21 Ras oncoproteins by causing selective immune abnormalities without general developmental defects. Our observations on the effects of NRAS activation indicate that RAS-inactivating drugs, such as farnesyltransferase inhibitors should be examined in human autoimmune and lymphocyte homeostasis disorders.     

Rituximab responsive immune thrombocytopenic purpura in an adult with underlying autoimmune lymphoproliferative syndrome due to a splice-site mutation (IVS7+2 T>C) affecting the Fas gene

A 36 yr-old man of Israeli descent with a history of childhood splenectomy for severe thrombocytopenia and a family history of autoimmune lymphoproliferative syndrome (ALPS), presented with severe immune thrombocytopenic purpura refractory to standard therapy. He was found to possess a heterozygous mutation in the Fas gene (also termed TNFRSF6, CD95, Apo-1) affecting the donor splice site of intron 7 (IVS7+2 T>C). This frameshift mutation truncates the cytoplasmic domain of the Fas death receptor, resulting in circulating CD4/8 double negative T lymphocytes, lymphadenopathy and autoimmune complications typical of ALPS. Administration of Rituximab in this patient was associated with a durable hematologic response (currently more than 12 months). This report highlights the need to consider rare inherited causes of thrombocytopenia in adults with a family history of immune cytopenia(s) and the effective use of anti-CD20 monoclonal antibody in patients unresponsive to immunosuppression and splenectomy.     

Advances in autoimmune lymphoproliferative syndromes

Autoimmune lymphoproliferative syndrome (ALPS) is a disorder of lymphocyte homeostasis. It is characterized by non-malignant lymphoproliferation autoimmunity mostly directed toward blood cells and increased risk of lymphoma. Majority of patients with ALPS harbor heterozygous germline mutations in the gene for the TNF receptor-family member Fas (CD 95, Apo-1) which are inherited in an autosomal dominant fashion. Somatic Fas mutations are the second most common genetic etiology of ALPS. Additionally mutations in the genes encoding Fas-ligand (FASLG), caspase 10 (CASP10) and caspase 8 (CASP8), NRAS and KRAS have been identified in a small number of patients with ALPS and related disorders. Approximately one-third of patients with ALPS have yet unidentified defect. ALPS was initially thought to be a very rare disease, but recent studies have shown that it may be more common than previously thought. Testing for ALPS should therefore be considered in patients with unexplained lymphadenopathy, cytopenias, and hepatosplenomegaly. There have been significant advances in the understanding of the pathophysiology of ALPS in last few years which has resulted in the development of new diagnostic criteria and a number of targeted therapies. This review describes the clinical and laboratory manifestations found in patients with ALPS, as well as the molecular basis for the disease and new advances in treatment.     

Unmasking Evans syndrome: T-cell phenotype and apoptotic response reveal autoimmune lymphoproliferative syndrome (ALPS)

Autoimmune lymphoproliferative syndrome (ALPS) is a rare disorder of disrupted lymphocyte homeostasis. Clinical manifestations of ALPS vary but typically include autoimmune cytopenias, organomegaly, lymphadenopathy, and increased risk of malignancies. A similar spectrum of symptoms may be seen in some patients with Evans syndrome (ES), a hematologic disorder defined by autoimmune destruction of at least 2 hematologic cell types. We hypothesized that a subset of patients diagnosed with ES may have ALPS. We screened 12 children with ES by flow cytometric analysis for CD4-/CD8- (double negative) T cells (DNTs) and with the definitive test for ALPS, defective in vitro Fas-mediated apoptosis. Six of the patients had elevated DNTs, suggestive of ALPS and also had defective Fas-mediated apoptosis. The other 6 patients displayed normal T-cell apoptosis; 5 of whom had normal DNTs, and 1 had a borderline result. Thus, 7 (58%) of 12 patients with ES had elevated DNTs suggestive of ALPS, with functional confirmation in 6 of 7. This suggests that analysis of DNTs may be a sensitive first-line screening test, serving as a marker of patients who should undergo definitive testing for ALPS. Our data further suggest that a number of patients with ES may have ALPS, a novel finding with important therapeutic implications.     

The use of the anti-malaria drug Fansidar® (pyrimethamine and sulphadoxine) in the treatment of a patient with autoimmune lymphoproliferative syndrome and Fas deficiency

Fas is a protein that plays a major role in the apoptotic mechanism of several cell types, including white blood cells (WBC). Mutations of the Fas gene in humans are known to lead to autoimmune lymphoproliferative syndrome (ALPS). Glucocorticoids or cytostatic drugs are sometimes used to treat the lymphoproliferation in these patients. When treated with the anti-malaria drug Fansidar^®, a patient with ALPS showed a marked shrinkage of the lymph node masses, decrease in peripheral blood lymphocytes (PBL) and an increase in neutrophil numbers. In addition, an increased Fas expression was seen on all types of leucocytes.     

Effect of anti-CD20 (rituximab) on resistant thrombocytopenia in autoimmune lymphoproliferative syndrome

Fas (CD95) plays an important role in apoptosis. Patients with defects in Fas have an autoimmune lymphoproliferative syndrome (ALPS) characterized by lymphadenopathy, autoimmune cytopenias and an increased incidence of lymphomas. There are approximately 70 known cases described worldwide. The autoimmune cytopenias are difficult to treat in this group. We describe a patient with a defect in the death domain of the FAS molecule who had autoimmune thrombocytopenia resistant to conventional therapy but which responded to a combination of rituximab and vincristine.     

Autoimmune lymphoproliferative syndrome

Autoimmune lymphoproliferative syndrome arises early in childhood in people who inherit mutations in genes that mediate lymphocyte apoptosis, or programmed cell death. In the immune system, antigen-induced lymphocyte apoptosis maintains immune homeostasis by limiting lymphocyte accumulation and minimizing reactions against self-antigens. In autoimmune lymphoproliferative syndrome, defective lymphocyte apoptosis manifests as chronic, nonmalignant adenopathy and splenomegaly; the expansion of an unusual population of CD4-CD8- T cells; and the development of autoimmune disease. Most cases of autoimmune lymphoproliferative syndrome involve heterozygous mutations in the lymphocyte surface protein Fas (CD95, Apo1) that impair a major apoptotic pathway. Prospective evaluations of patients and their families have revealed an ever-expanding spectrum of autoimmune lymphoproliferative syndrome and its major complications.