Autoimmune lymphoproliferative immunodeficiencies (ALPIDs): A proposed approach to redefining ALPS and other lymphoproliferative immune disorders.

Chronic nonmalignant lymphoproliferation and autoimmune cytopenia are relevant manifestations of immunohematologic diseases of childhood. Their diagnostic classification is challenging but important for therapy. Autoimmune lymphoproliferative syndrome (ALPS) is a genetically defined inborn error of immunity combining these manifestations, but it can explain only a small proportion of cases. Diagnostic categories such as ALPS-like disease, common variable immunodeficiency, or Evans syndrome have therefore been used. Advances in genetics and increasing availablity of targeted therapies call for more therapy-oriented disease classification. Moreover, recent discoveries in the (re)analysis of genetic conditions affecting FAS signaling ask for a more precise definition of ALPS. In this review, we propose the term autoimmune lymphoproliferative immunodeficiencies for a disease phenotype that is enriched for patients with genetic diseases for which targeted therapies are available. For patients without a current molecular diagnosis, this term defines a subgroup of immune dysregulatory disorders for further studies. Within the concept of autoimmune lymphoproliferative immunodeficiencies, we propose a revision of the ALPS classification, restricting use of this term to conditions with clear evidence of perturbation of FAS signaling and resulting specific biologic and clinical consequences. This proposed approach to redefining ALPS and other lymphoproliferative conditions provides a framework for disease classification and diagnosis that is relevant for the many specialists confronted with these diseases.

A Spectrum of Clinical Findings from ALPS to CVID: Several Novel LRBA Defects.

INTRODUCTION: Autosomal recessively inherited lipopolysaccharide-responsive beige-like anchor (LRBA) protein deficiency was shown to be responsible for different types of inborn errors of immunity, such as common variable immunodeficiency (CVID) and autoimmune lymphoproliferative syndrome (ALPS). The aim of this study was to compare patients with LRBA-related ALPS and LRBA-related CVID, to describe their clinical and laboratory phenotypes, and to prepare an algorithm for their diagnosis and management. METHODS: Fifteen LRBA-deficient patients were identified among 31 CVID and 14 possible ALPS patients with Western blotting (WB), primary immunodeficiency disease (PIDD) gene, next-generation panel screening (NGS), and whole exome sequencing (WES). RESULTS: The median age on admission and age of diagnosis were 7 years (0.3-16.5) and 11 years (5-44), respectively. Splenomegaly was seen in 93.3% (14/15) of the patients on admission. Splenectomy was performed to 1/5. Recurrent upper respiratory tract infections (93.3% (14/15)), autoimmune cytopenia (80% (12/15)), chronic diarrhea (53.3% (8/15)), lower respiratory tract infections (53.3% (8/15)), lymphoma (26.6% (4/15)), Evans syndrome (26.6% (4/15)), and autoimmune thyroiditis (20% (3/15)) were common clinical findings and diseases. Lymphopenia (5/15), intermittant neutropenia (4/15), eosinophilia (4/15), and progressive hypogammaglobulinemia are recorded in given number of patients. Double negative T cells (TCRαß+CD4-CD8-) were increased in 80% (8/10) of the patients. B cell percentage/numbers were low in 60% (9/15) of the patients on admission. Decreased switched memory B cells, decreased naive and recent thymic emigrant (RTE) Thelper (Th) cells, markedly increased effector memory/effector memory RA+ (TEMRA) Th were documented. Large PD1+ population, increased memory, and enlarged follicular helper T cell population in the CD4+ T cell compartment was seen in one of the patients. Most of the deleterious missense mutations were located in the DUF1088 and BEACH domains. Interestingly, one of the two siblings with the same homozygous LRBA defect did not have any clinical symptom. Hematopoietic stem cell transplantation (HSCT) was performed to 7/15 (46.6%) of the patients. Transplanted patients are alive and well after a median of 2 years (1-3). In total, one patient died from sepsis during adulthood before HSCT. CONCLUSION: Patients with LRBA deficiency may initially be diagnosed as CVID or ALPS in the clinical practice. Progressive decrease in B cells as well as IgG in ALPS-like patients and addition of IBD symptoms in the follow-up should raise the suspicion for LRBA deficiency. Decreased switched memory B cells, decreased naive and recent thymic emigrant (RTE) Th cells, and markedly increased effector memory/effector memory RA+ Th cells (TEMRA Th) cells are important for the diagnosis of the patients in addition to clinical features. Analysis of protein by either WB or flow cytometry is required when the clinicians come across especially with missense LRBA variants of uncertain significance. High rate of malignancy shows the regulatory T cell's important role of immune surveillance. HSCT is curative and succesful in patients with HLA-matched family donor.

The Autoimmune Lymphoproliferative Syndrome with Defective FAS or FAS-Ligand Functions.

The autoimmune lymphoproliferative syndrome (ALPS) is a non-malignant and non-infectious uncontrolled proliferation of lymphocytes accompanied by autoimmune cytopenia. The genetic etiology of the ALPS was described in 1995 by the discovery of the FAS gene mutations. The related apoptosis defect accounts for the accumulation of autoreactive lymphocytes as well as for specific clinical and biological features that distinguish the ALPS-FAS from other monogenic defects of this apoptosis pathway, such as FADD and CASPASE 8 deficiencies. The ALPS-FAS was the first description of a monogenic cause of autoimmunity, but its non-Mendelian expression remained elusive until the description of somatic and germline mutations in ALPS patients. The recognition of these genetic diseases brought new information on the role of this apoptotic pathway in controlling the adaptive immune response in humans.

Pearls and pitfalls: Autoimmune lymphoproliferative syndrome and autoimmune lymphoproliferative syndrome-like disease.

A case of autoimmune lymphoproliferative syndrome (ALPS) was presented, followed by a discussion of the clinical characteristics, pathophysiology, diagnosis, and management of this disease. Clinical pearls and pitfalls are emphasized for the use of the practicing allergist and the fellow in-training. The diagnosis of ALPS was guided by published criteria. A careful history and workup were needed to exclude other possible etiologies for the patient's symptoms and physical findings. ALPS often carries significant morbidity and is best managed through a multidisciplinary approach.

Why do T cells cause so much trouble?

In this issue of Blood, Price et al document a 20-year experience with autoimmune lymphoproliferative syndrome (ALPS) patients and healthy mutation-positive relatives, showing that defective lymphocyte apoptosis is associated with an increased incidence of lymphomas.

Natural history of autoimmune lymphoproliferative syndrome associated with FAS gene mutations.

Autoimmune lymphoproliferative syndrome (ALPS) presents in childhood with nonmalignant lymphadenopathy and splenomegaly associated with a characteristic expansion of mature CD4 and CD8 negative or double negative T-cell receptor αß(+) T lymphocytes. Patients often present with chronic multilineage cytopenias due to autoimmune peripheral destruction and/or splenic sequestration of blood cells and have an increased risk of B-cell lymphoma. Deleterious heterozygous mutations in the FAS gene are the most common cause of this condition, which is termed ALPS-FAS. We report the natural history and pathophysiology of 150 ALPS-FAS patients and 63 healthy mutation-positive relatives evaluated in our institution over the last 2 decades. Our principal findings are that FAS mutations have a clinical penetrance of <60%, elevated serum vitamin B12 is a reliable and accurate biomarker of ALPS-FAS, and the major causes of morbidity and mortality in these patients are the overwhelming postsplenectomy sepsis and development of lymphoma. With longer follow-up, we observed a significantly greater relative risk of lymphoma than previously reported. Avoiding splenectomy while controlling hypersplenism by using corticosteroid-sparing treatments improves the outcome in ALPS-FAS patients. This trial was registered at www.clinicaltrials.gov as #NCT00001350.

Diagnostic evaluation of paediatric autoimmune lymphoproliferative immunodeficiencies (ALPID): a prospective cohort study.

BACKGROUND: Lymphoproliferation and autoimmune cytopenias characterise autoimmune lymphoproliferative syndrome. Other conditions sharing these manifestations have been termed autoimmune lymphoproliferative syndrome-like diseases, although they are frequently more severe. The aim of this study was to define the genetic, clinical, and immunological features of these disorders to improve their diagnostic classification. METHODS: In this prospective cohort study, patients were referred to the Center for Chronic Immunodeficiency in Freiburg, Germany, between Jan 1, 2008 and March 5, 2022. We enrolled patients younger than 18 years with lymphoproliferation and autoimmune cytopenia, lymphoproliferation and at least one additional sign of an inborn error of immunity (SoIEI), bilineage autoimmune cytopenia, or autoimmune cytopenia and at least one additional SoIEI. Autoimmune lymphoproliferative syndrome biomarkers were determined in all patients. Sanger sequencing followed by in-depth genetic studies were recommended for patients with biomarkers indicative of autoimmune lymphoproliferative syndrome, while IEI panels, exome sequencing, or genome sequencing were recommended for patients without such biomarkers. Genetic analyses were done as decided by the treating physician. The study was registered on the German Clinical Trials Register, DRKS00011383, and is ongoing. FINDINGS: We recruited 431 children referred for autoimmune lymphoproliferative syndrome evaluation, of whom 236 (55%) were included on the basis of lymphoproliferation and autoimmune cytopenia, 148 (34%) on the basis of lymphoproliferation and another SoIEI, 33 (8%) on the basis of autoimmune bicytopenia, and 14 (3%) on the basis of autoimmune cytopenia and another SoIEI. Median age at diagnostic evaluation was 9·8 years (IQR 5·5-13·8), and the cohort comprised 279 (65%) boys and 152 (35%) girls. After biomarker and genetic assessments, autoimmune lymphoproliferative syndrome was diagnosed in 71 (16%) patients. Among the remaining 360 patients, 54 (15%) had mostly autosomal-dominant autoimmune lymphoproliferative immunodeficiencies (AD-ALPID), most commonly affecting JAK-STAT (26 patients), CTLA4-LRBA (14), PI3K (six), RAS (five), or NFκB (three) signalling. 19 (5%) patients had other IEIs, 17 (5%) had non-IEI diagnoses, 79 (22%) were unresolved despite extended genetics (ALPID-U), and 191 (53%) had insufficient genetic workup for diagnosis. 16 (10%) of 161 patients with a final diagnosis had somatic mutations. Alternative classification of patients fulfilling common variable immunodeficiency or Evans syndrome criteria did not increase the proportion of genetic diagnoses. INTERPRETATION: The ALPID phenotype defined in this study is enriched for patients with genetic diseases treatable with targeted therapies. The term ALPID might be useful to focus diagnostic and therapeutic efforts by triggering extended genetic analysis and consideration of targeted therapies, including in some children currently classified as having common variable immunodeficiency or Evans syndrome. FUNDING: Deutsche Forschungsgemeinschaft under Germany's Excellence Strategy. TRANSLATION: For the German translation of the abstract see Supplementary Materials section.

How I treat autoimmune lymphoproliferative syndrome.

Autoimmune lymphoproliferative syndrome (ALPS) represents a failure of apoptotic mechanisms to maintain lymphocyte homeostasis, permitting accumulation of lymphoid mass and persistence of autoreactive cells that often manifest in childhood with chronic nonmalignant lymphadenopathy, hepatosplenomegaly, and recurring multilineage cytopenias. Cytopenias in these patients can be the result of splenic sequestration as well as autoimmune complications manifesting as autoimmune hemolytic anemia, immune-mediated thrombocytopenia, and autoimmune neutropenia. More than 300 families with hereditary ALPS have now been described; nearly 500 patients from these families have been studied and followed worldwide over the last 20 years by our colleagues and ourselves. Some of these patients with FAS mutations affecting the intracellular portion of the FAS protein also have an increased risk of B-cell lymphoma. The best approaches to diagnosis, follow-up, and management of ALPS, its associated cytopenias, and other complications resulting from infiltrative lymphoproliferation and autoimmunity are presented.

Autoimmune lymphoproliferative syndrome: A disorder of immune dysregulation.

Autoimmune Lymphoproliferative Syndrome (ALPS) is an autoimmune disease that has been reported in over 2200 patients. It is a rare, genetic disease where pathogenic variants occur in the extrinsic pathway of apoptosis. Various mutations in different genes, such as FAS, FASL, and CASP10, can result in ALPS. Most commonly, pathogenic variants occur in the FAS receptor. This malfunctioning pathway allows for the abnormal accumulation of lymphocytes, namely CD3 + TCRαß+CD4 - CD8- (double negative (DN) T) cells, which are a hallmark of the disease. This disease usually presents in childhood with lymphadenopathy and splenomegaly as a result of lymphoproliferation. Over time, these patients may develop cytopenias or lymphomas because of irregularities in the immune system. Current treatments include glucocorticoids, mycophenolate mofetil, sirolimus, immunoglobulin G, and rituximab. These medications serve to manage the symptoms and there are no standardized recommendations for the management of ALPS. The only curative therapy is a bone marrow transplant, but this is rarely done because of the complications. This review serves to broaden the understanding of ALPS by discussing the mechanism of immune dysregulation, how the symptoms manifest, and the mechanisms of treatment. Additionally, we discuss the epidemiology, comorbidities, and medications relating to ALPS patients across the United States using data from Cosmos.

Cutting edge: Lymphoproliferation caused by Fas deficiency is dependent on the transcription factor eomesodermin.

A hallmark of autoimmune lymphoproliferative syndrome (ALPS), caused by mutation of the Fas death receptor, is massive lymphadenopathy from aberrant expansion of CD4(-)CD8(-) (double-negative [DN]) T cells. Eomesodermin (Eomes) is a member of the T-box family of transcription factors and plays critical roles in effector cell function and memory cell fitness of CD8(+) T lymphocytes. We provide evidence in this study that DN T cells exhibit dysregulated expression of Eomes in humans and mice with ALPS. We also find that T cell-specific deletion of Eomes prevents lymphoid hypertrophy and accumulation of DN T cells in Fas-mutant mice. Although Eomes has critical physiological roles in the function and homeostasis of CD8(+) T cells, overexpression of Eomes appears to enable pathological induction or expansion of unusual CD8-related T cell subsets. Thus, antagonism of Eomes emerges as a therapeutic target for DN T cell ablation in ALPS.

Non-malignant, non-infectious lymphoproliferation: challenges in the diagnosis and treatment of autoimmune lymphoproliferative syndrome / Nem malignus, nem infectiosus lymphoproliferatio: kihívások az autoimmun lymphoproliferativ szindróma diagnosztikájában és kezelésében.

Összefoglaló. Az autoimmun lymphoproliferativ szindróma egy ritka, immundeficientiával járó genetikai betegség. Hátterében az extrinszik apoptotikus útvonal génjeinek örökletes vagy szerzett mutációi és a következményesen kialakuló, aktivált lymphocyták negatív szelekciójának a defektusa áll. Az autoimmun lymphoproliferativ szindróma klinikai megjelenésére jellemzo a jóindulatú lymphocytaburjánzás következtében kialakuló lymphadenopathia és lépmegnagyobbodás. Gyakran társul olyan autoimmun kórképekkel, mint az autoimmun haemolyticus anaemia vagy az autoimmun thrombocytopenia. A betegségben jellemzo laboratóriumi eltérések a következok: az αß+ CD4-/CD8- kettos negatív T-sejtek szaporulata, a szolúbilis Fas-ligand, az interleukin-10 és interleukin-18, valamint a B12-vitamin szérumszintjének emelkedése. A kórkép diagnózisához hozzátartozik az in vitro Fas-mediált apoptózis funkciójának vizsgálata, valamint a genetikai vizsgálat. Differenciáldiagnosztikai szempontból fontos elkülöníteni a lymphomáktól, valamint az autoimmun lymphoproliferativ szindrómaszeru betegségektol. A kezelés alapja a társuló autoimmun kórképek tüneteinek csökkentése immunszuppresszív terápiával. Orv Hetil. 2022; 163(4): 123-131. Summary. The autoimmune lymphoproliferative syndrome is a rare genetic disorder causing immunodeficiency. In the background of the disease, germline or somatic mutations of genes participating in the extrinsic apoptotic pathway and the consequential defect in the negative selection of activated lymphocytes were discovered. The clinical appearance of autoimmune lymphoproliferative syndrome consists of non-malignant lymphoproliferation, lymphadenopathy and splenomegaly, it is frequently accompanied by autoimmune disorders such as autoimmune haemolytic anaemia or autoimmune thrombocytopenia. The main diagnostic laboratory findings of this disease are the following: an elevation in αß+, CD4-/CD8- double-negative T cell count, elevated serum levels of soluble Fas-ligand, interleukin-10, interleukin-18 and vitamin B12. Other useful laboratory tests are the in vitro Fas-mediated apoptotic functional assay and the genetic screening for gene mutations. Differential diagnosis should exclude malignant lymphoproliferation in lymphomas and non-malignant autoimmune lymphoprolipherative syndrome-like diseases. The main aim of the treatment is the amelioration of the accompanying autoimmune disease with immunosuppressive therapy. Orv Hetil. 2022; 163(4): 123-131.

[Autoimmune lymphoproliferative syndrome: a case report]. / Syndrome lymphoprolifératif avec autoimmunité: à propos d'un cas.

Autoimmune lymphoproliferative syndrome (ALPS) is a rare genetic disorder of lymphocyte homeostasis, resulting from mutations in the Fas apoptotic pathway. It is characterized by non-infectious and non-malignant chronic lymphoproliferation and an increased risk of lymphoid malignancy. The diagnosis of this condition usually combines chronic lymphadenopathy and/or splenomegaly exceeding 6 months, autoimmune cytopenias, with an elevated level of CD3+CD4-CD8- Tαß lymphocytes, known as "double-negative" T cells. Differential diagnosis includes infections, autoimmune diseases or malignancies. Although clinical examination and laboratory tests are highly suggestive, this disease goes widely unrecognized. We here report, for the first time, the case of ALPS, a Moroccan patient, and aged 8 years, with recurrent fever, splenomegaly and adenopathies. Paraclinical examinations revealed chronic pancytopenia, higher than normal TαÎ2 double negative lymphocytes, hypergammaglobulinemia, and elevated serum levels of soluble FAS ligand. The diagnosis of ALPS was made. First-line treatment included corticosteroids and immunoglobulins. Then the patient received mycophenolate followed by Sirolimus. This treatment resulted in better clinical and laboratory tests results. Our aim is to raise awareness of this rare condition, which may be under-diagnosed, among physicians.

Detection and evolutionary dynamics of somatic FAS variants in autoimmune lymphoproliferative syndrome: Diagnostic implications.

Autoimmune lymphoproliferative syndrome (ALPS) is a rare primary immune disorder characterized by impaired apoptotic homeostasis. The clinical characteristics include lymphoproliferation, autoimmunity (mainly cytopenia), and an increased risk of lymphoma. A distinctive biological feature is accumulation (>2.5%) of an abnormal cell subset composed of TCRαß+ CD4-CD8- T cells (DNTs). The most common genetic causes of ALPS are monoallelic pathogenic variants in the FAS gene followed by somatic FAS variants, mainly restricted to DNTs. Identification of somatic FAS variants has been typically addressed by Sanger sequencing in isolated DNTs. However, this approach can be costly and technically challenging, and may not be successful in patients with normal DNT counts receiving immunosuppressive treatment. In this study, we identified a novel somatic mutation in FAS (c.718_719insGTCG) by Sanger sequencing on purified CD3+ cells. We then followed the evolutionary dynamics of the variant along time with an NGS-based approach involving deep amplicon sequencing (DAS) at high coverage (20,000-30,000x). Over five years of clinical follow-up, we obtained six blood samples for molecular study from the pre-treatment (DNTs>7%) and treatment (DNTs<2%) periods. DAS enabled detection of the somatic variant in all samples, even the one obtained after five years of immunosuppressive treatment (DNTs: 0.89%). The variant allele frequency (VAF) range was 4%-5% in pre-treatment samples and <1.5% in treatment samples, and there was a strong positive correlation between DNT counts and VAF (Pearson's R: 0.98, p=0.0003). We then explored whether the same approach could be used in a discovery setting. In the last follow-up sample (DNT: 0.89%) we performed somatic variant calling on the FAS exon 9 DAS data from whole blood and purified CD3+ cells using VarScan 2. The c.718_719insGTCG variant was identified in both samples and showed the highest VAF (0.67% blood, 1.58% CD3+ cells) among >400 variants called. In summary, our study illustrates the evolutionary dynamics of a somatic FAS mutation before and during immunosuppressive treatment. The results show that pathogenic somatic FAS variants can be identified with the use of DAS in whole blood of ALPS patients regardless of their DNT counts.

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.

Primary Immune Regulatory Disorders With an Autoimmune Lymphoproliferative Syndrome-Like Phenotype: Immunologic Evaluation, Early Diagnosis and Management.

Primary immune regulatory disorders (PIRD) are associated with autoimmunity, autoinflammation and/or dysregulation of lymphocyte homeostasis. Autoimmune lymphoproliferative syndrome (ALPS) is a PIRD due to an apoptotic defect in Fas-FasL pathway and characterized by benign and chronic lymphoproliferation, autoimmunity and increased risk of lymphoma. Clinical manifestations and typical laboratory biomarkers of ALPS have also been found in patients with a gene defect out of the Fas-FasL pathway (ALPS-like disorders). Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA), we identified more than 600 patients suffering from 24 distinct genetic defects described in the literature with an autoimmune lymphoproliferative phenotype (ALPS-like syndromes) corresponding to phenocopies of primary immunodeficiency (PID) (NRAS, KRAS), susceptibility to EBV (MAGT1, PRKCD, XIAP, SH2D1A, RASGRP1, TNFRSF9), antibody deficiency (PIK3CD gain of function (GOF), PIK3R1 loss of function (LOF), CARD11 GOF), regulatory T-cells defects (CTLA4, LRBA, STAT3 GOF, IL2RA, IL2RB, DEF6), combined immunodeficiencies (ITK, STK4), defects in intrinsic and innate immunity and predisposition to infection (STAT1 GOF, IL12RB1) and autoimmunity/autoinflammation (ADA2, TNFAIP3,TPP2, TET2). CTLA4 and LRBA patients correspond around to 50% of total ALPS-like cases. However, only 100% of CTLA4, PRKCD, TET2 and NRAS/KRAS reported patients had an ALPS-like presentation, while the autoimmunity and lymphoproliferation combination resulted rare in other genetic defects. Recurrent infections, skin lesions, enteropathy and malignancy are the most common clinical manifestations. Some approaches available for the immunological study and identification of ALPS-like patients through flow cytometry and ALPS biomarkers are provided in this work. Protein expression assays for NKG2D, XIAP, SAP, CTLA4 and LRBA deficiencies and functional studies of AKT, STAT1 and STAT3 phosphorylation, are showed as useful tests. Patients suspected to suffer from one of these disorders require rapid and correct diagnosis allowing initiation of tailored specific therapeutic strategies and monitoring thereby improving the prognosis and their quality of life.