Autoimmune lymphoproliferative syndrome type III: an indefinite disorder

Autoimmune Lymphoproliferative Syndrome in Children with Nonmalignant Organomegaly, Chronic Immune Cytopenia, and Newly Diagnosed Lymphoma

This study investigated the frequency of and predictive factors for autoimmune lymphoproliferative syndrome (ALPS) in children with lymphoma, chronic immune cytopenia, and nonmalignant organomegaly. Thirty-four children with suspected ALPS (n=13, lymphoma; n=12, immune cytopenia; n=9, nonmalignant organomegaly) were included. Double-negative T-cells, lymphocyte apoptosis, and genetic findings were analyzed. Patients were stratified into two groups as proven/probable ALPS and clinically suspected patients according to the ALPS diagnostic criteria. Of the 34 patients, 18 (53%) were diagnosed with proven/probable ALPS. One patient had a mutation (c.652-2A>C) in the FAS gene. The remaining 16 (47%) patients were defined as clinically suspected patients. Predictive factors for ALPS were anemia and thrombocytopenia in patients with lymphoma, splenomegaly and lymphadenopathy in patients with immune cytopenia, and young age in patients with nonmalignant organomegaly. ALPS may not be rare in certain risk groups. Our study indicates that screening for ALPS may be useful in children having lymphoma with cytopenia at diagnosis, in those having nonmalignant organomegaly with immune cytopenia, and in those having chronic immune thrombocytopenic purpura or autoimmune hemolytic anemia with organomegaly developing during follow-up.

Key diagnostic markers for autoimmune lymphoproliferative syndrome with molecular genetic diagnosis

Autoimmune lymphoproliferative syndrome (ALPS) is a rare immunodeficiency caused by mutations in genes affecting the extrinsic apoptotic pathway (FAS, FASL, CASP10). This study evaluated the clinical manifestations, laboratory findings, and molecular genetic results of 215 patients referred as possibly having ALPS. Double-negative T-cell (DNT) percentage and in vitro apoptosis functional tests were evaluated by fluorescence-activated cell sorting; interleukin 10 (IL-10) and IL-18 and soluble FAS ligand (sFASL) were measured by enzyme-linked immunosorbent assay. Genetic analysis was performed by next-generation sequencing. Clinical background data were collected from patients’ records. Patients were categorized into definite, suspected, or unlikely ALPS groups, and laboratory parameters were compared among these groups. Of 215 patients, 38 met the criteria for definite ALPS and 17 for suspected ALPS. The definite and suspected ALPS patient populations showed higher DNT percentages than unlikely ALPS and had higher rates of lymphoproliferation. Definite ALPS patients had a significantly more abnormal in vitro apoptosis function, with lower annexin, than patients with suspected ALPS (P = .002) and patients not meeting ALPS criteria (P < .001). The combination of elevated DNTs and an abnormal in vitro apoptosis functional test was the most useful in identifying all types of ALPS patients; the combination of an abnormal in vitro apoptosis functional test and elevated sFASLs was a predictive marker for ALPS-FAS group identification. Lymphoproliferation, apoptosis functional test, and DNTs are the most sensitive markers; elevated IL-10 and IL-18 are additional indicators for ALPS. The combination of elevated sFASLs and abnormal apoptosis function was the most valuable prognosticator for patients with FAS mutations.

Causes and consequences of the autoimmune lymphoproliferative syndrome

Autoimmune lymphoproliferative syndrome (ALPS) is the first autoimmune hematological disease whose genetic basis has been defined. It is a disorder of apoptosis in which the inability of lymphocytes to die leads to lymphadenopathy, hypersplenism, and autoimmune cytopenias of childhood onset. More than 200 ALPS patients have been studied over the last 15 years and followed by our colleagues and ourselves at the Clinical Center of the National Institutes of Health. Based upon this experience we have determined that patients with germline mutations of the intracellular domain of Fas protein, the most frequent single genetic cause of ALPS, have a significantly increased risk of developing Hodgkin and non-Hodgkin lymphoma (NHL), underscoring the critical role played by cell surface receptor-mediated apoptosis in eliminating redundant proliferating lymphocytes with autoreactive and oncogenic potential. The major determinants of morbidity and mortality in ALPS are the severity of the autoimmune disease, hypersplenism, asplenia-related sepsis, and the risk of lymphoma, which in itself requires long-term surveillance. Though most episodes of cytopenias respond to courses of conventional immunomodulatory agents, some ALPS patients, especially those with massive splenomegaly and hypersplenism, may require splenectomy and/or ongoing immunosuppressive treatment. Thus, ALPS highlights the importance of cell death pathways in health and disease.

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.

Autoimmune lymphoproliferative syndrome (ALPS) in a patient with a new germline Fas gene mutation

Autoimmune lymphoproliferative syndrome (ALPS) is a rare genetic disorder characterized by chronic lymphoproliferation, autoimmune manifestations and expansion of TCRalphabeta+CD4-CD8- lymphocytes. The main pathogenic factor is a defective Fas-mediated apoptosis generally caused by mutations in the Fas gene. This report describes a new heterozygous Fas gene mutation in a boy with clinical and immunological features of ALPS. In vitro, T-cell blasts from the patient are completely resistant to the effects on the anti-Fas cytotoxic mAb CH-11, they also have a higher proliferation rate than T cells from healthy donors, while PHA-induced AICD is normal. The location of the mutation (I246S) found in the intracytoplasmic death domain, and the conservation of that residue in four different species from human suggest that I246 is an essential amino acid for Fas function. The patient has inherited the mutation from his father who also shows defective Fas-mediated apoptosis but the clinical and immunological manifestations are much less severe. These results provide evidence that the penetrance of genetic defects in Fas is variable and that other factors may influence the phenotype of the disease.

A homozygous Fas ligand gene mutation in a patient causes a new type of autoimmune lymphoproliferative syndrome

Autoimmune lymphoproliferative syndrome (ALPS) is characterized by lymphoproliferation and autoimmune clinical manifestations and is generally caused by defective Fas-mediated apoptosis. This report describes the first homozygous FASL gene mutation in a woman with clinical and immunologic features of ALPS. T-cell blasts from the patient did not induce FasL-mediated apoptosis on Fas-transfected murine L1210 or on Jurkat cells, and activation-induced cell death was impaired. Furthermore, Fas-dependent cytotoxicity was drastically reduced in COS cells transfected with the mutant FasL. In addition, FasL expression on T-cell blasts from the patient was similar to that observed in a healthy control, despite its bearing the high-producer genotype -844C/C in the FASL promoter. Sequencing of the patient's FASL gene revealed a new mutation in exon 4 (A247E). The location of A247E in the FasL extracellular domain and the conservation of the protein sequence of that region recorded in 8 species different from humans support the essential role of FasL COOH terminal domain in Fas/FasL binding. These findings provide evidence that inherited nonlethal FASL abnormalities cause an uncommon apoptosis defect producing lymphoproliferative disease, and they highlight the need for a review of the current ALPS classification to include a new ALPS type Ic subgroup.

Monogenic autoimmune diseases — lessons of self-tolerance

The molecular defects recently identified in the rare monogenic autoimmune diseases (AIDs) have pinpointed critical steps in the pathways that contribute to the development of normal immune responses and self-tolerance. Recent studies of autoimmune polyendocrinopathy syndrome type 1, autoimmune lymphoproliferative syndrome, immunodysregulation, polyendocrinopathy and enteropathy, X-linked, IL-2 receptor alpha-chain deficiency, and, in particular, their corresponding mouse models, have revealed the details of the molecular mechanisms of normal immune tolerance, and exposed how defects in these mechanisms result in human autoimmunity. In addition to a deeper understanding of the immune system, detailed molecular characterization of monogenic AIDs will help us to understand the mechanisms behind common polygenic AIDs and, furthermore, to develop novel therapies and intervention strategies to treat them.

Autoimmune lymphoproliferative syndrome: etiology, diagnosis, and management

Autoimmune lymphoproliferative syndrome (ALPS) is a childhood disorder characterized by chronic, nonmalignant lymphoproliferation and autoimmunity, most commonly involving cells of hematopoietic origin. Mutations of the tumor necrosis factor receptor super family member 6 (TNFRSF6) gene, coding for the apoptosis-inducing protein Fas (Apo-1, CD95) are involved in the physiopathology of the syndrome, although the complete mechanism by which the syndrome is caused has not yet been unraveled. Although the syndrome has a benign nature, life-threatening complications can demand treatment. Treatment schedules, including corticosteroids, low doses of chemotherapy, granulocyte colony stimulating factor, or splenectomy, have varying results. Treatment with the antimalarial drug pyrimethamine/sulfadoxine (25/500mg per tablet) seems to be a new, well tolerated, and efficient approach, although larger studies will have to demonstrate the true value of this drug in patients with ALPS.

Reversion of autoimmune lymphoproliferative syndrome with an antimalarial drug: preliminary results of a clinical cohort study and molecular observations

Autoimmune lymphoproliferative syndrome (ALPS) is a paediatric disease characterized by lymphoproliferation and autoimmunity. Most patients are known to carry heterozygous mutations of the TNFRSF6 gene leading to diminished Fas-mediated apoptosis and failure of activated lymphocytes to undergo apoptosis. A subgroup of patients without the TNFRSF6 gene mutation has similar defective apoptosis and clinical features. No effective treatment has been reported so far. Glucocorticoids, intravenous immunoglobulin and/or immunosuppressive drugs have usually led to only transient clinical improvement. Seven ALPS patients (two type Ia and five type III) were treated with the antimalarial drug Fansidar. No toxicity was observed. An objective response was seen in six of them and, in two, the treatment was stopped without reappearance of the symptoms. Moreover, a marked decrease in interleukin-10 levels was observed in two patients during the treatment. We found that the drug induced apoptosis in activated lymphocytes through activation of the mitochondrial apoptotic pathway.