Autoimmune Lymphoproliferative Syndrome
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Autoimmune lymphoproliferative syndrome (ALPS) is a form of
lymphoproliferative disorder Lymphoproliferative disorders (LPDs) refer to a specific class of diagnoses, comprising a group of several conditions, in which lymphocytes are produced in excessive quantities. These disorders primarily present in patients who have a compromised ...
(LPDs). It affects
lymphocyte A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include T cells (for cell-mediated and cytotoxic adaptive immunity), B cells (for humoral, antibody-driven adaptive immunity), an ...
apoptosis Apoptosis (from ) is a form of programmed cell death that occurs in multicellular organisms and in some eukaryotic, single-celled microorganisms such as yeast. Biochemistry, Biochemical events lead to characteristic cell changes (Morphology (biol ...
. It is a rare genetic disorder of abnormal
lymphocyte A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include T cells (for cell-mediated and cytotoxic adaptive immunity), B cells (for humoral, antibody-driven adaptive immunity), an ...
survival caused by defective Fas mediated
apoptosis Apoptosis (from ) is a form of programmed cell death that occurs in multicellular organisms and in some eukaryotic, single-celled microorganisms such as yeast. Biochemistry, Biochemical events lead to characteristic cell changes (Morphology (biol ...
. Normally, after infectious insult, the immune system down-regulates by increasing Fas expression on activated B and T lymphocytes and Fas-ligand on activated T lymphocytes. Fas and Fas-ligand interact to trigger the
caspase Caspases (cysteine-aspartic proteases, cysteine aspartases or cysteine-dependent aspartate-directed proteases) are a family of protease enzymes playing essential roles in programmed cell death. They are named caspases due to their specific cyste ...
cascade, leading to cell apoptosis. Patients with ALPS have a defect in this apoptotic pathway, leading to chronic non-malignant lymphoproliferation, autoimmune disease, and secondary cancers.


Signs and symptoms

All people with ALPS have signs of lymphoproliferation, which makes it the most common clinical manifestation of the disease. The increased proliferation of lymphoid cells can cause the size of lymphoid organs such as the
lymph node A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that includ ...
s and
spleen The spleen (, from Ancient Greek '' σπλήν'', splḗn) is an organ (biology), organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The spleen plays important roles in reg ...
to increase (
lymphadenopathy Lymphadenopathy or adenopathy is a disease of the lymph nodes, in which they are abnormal in size or consistency. Lymphadenopathy of an inflammatory type (the most common type) is lymphadenitis, producing swollen or enlarged lymph nodes. In c ...
and
splenomegaly Splenomegaly is an enlargement of the spleen. The spleen usually lies in the left upper quadrant (LUQ) of the human abdomen. Splenomegaly is one of the four cardinal signs of ''hypersplenism'' which include: some reduction in number of circulat ...
, present in respectively over 90% and over 80% of patients). The
liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...
is enlarged (
hepatomegaly Hepatomegaly is enlargement of the liver. It is a non-specific sign (medicine), medical sign, having many causes, which can broadly be broken down into infection, hepatic tumours, and metabolic disorder. Often, hepatomegaly presents as an abdomin ...
) in 30–40% of patients. Autoimmune disease is the second most common clinical manifestation and one that most often requires treatment. The most common autoimmune presentations include autoimmune cytopenias, which can be mild to very severe and intermittent or chronic. These include
autoimmune hemolytic anemia Autoimmune hemolytic anemia (AIHA) occurs when a person's immune system produces antibodies directed against their own red blood cells (RBCs). These antibodies attach to red cells, causing them to break down ( lyse), and reducing the number of ox ...
, autoimmune neutropenia, and autoimmune thrombocytopenia. Other autoimmune manifestations can be similar to
systemic lupus erythematosus Lupus, formally called systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Common ...
(least common, affecting <5% of patients). Manifestations within the nervous system can include autoimmune
cerebellar ataxia Cerebellar ataxia is a form of ataxia originating in the cerebellum. Non-progressive congenital ataxia (NPCA) is a classical presentation of cerebral ataxias. Cerebellar ataxia can occur as a result of many diseases and may present with symptoms ...
,
Guillain–Barré syndrome Guillain–Barré syndrome (GBS) is a rapid-onset Paralysis, muscle weakness caused by the immune system damaging the peripheral nervous system. Typically, both sides of the body are involved, and the initial symptoms are changes in sensation ...
, and
transverse myelitis Transverse myelitis (TM) is a rare neurological condition wherein the spinal cord is Inflammation, inflamed. The adjective ''wikt:transverse#Adjective, transverse'' implies that the spinal inflammation (myelitis) extends horizontally throughout ...
. Manifestations in the gastrointestinal system can include
atrophic gastritis Atrophic gastritis is a process of chronic inflammation of the gastric mucosa of the stomach, leading to a loss of gastric gland, gastric glandular cells and their eventual replacement by Intestinal metaplasia, intestinal and fibrous tissues. As ...
, and
autoimmune hepatitis Autoimmune hepatitis, formerly known as lupoid hepatitis, plasma cell hepatitis, or autoimmune chronic active hepatitis, is a chronic, autoimmune disease of the liver that occurs when the body's immune system attacks liver cells, causing the liv ...
,
esophagitis Esophagitis, also spelled oesophagitis, is a disease characterized by inflammation of the esophagus. The esophagus is a tube composed of a mucosal lining, and longitudinal and circular smooth muscle fibers. It connects the pharynx to the stoma ...
,
colitis Colitis is swelling or inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and ...
, and
pancreatitis Pancreatitis is a condition characterized by inflammation of the pancreas. The pancreas is a large organ behind the stomach that produces digestive enzymes and a number of hormone A hormone (from the Ancient Greek, Greek participle , "se ...
. Other manifestations can affect the skin (
hives Hives, also known as urticaria, is a kind of skin rash with red or flesh-colored, raised, itchy bumps. Hives may burn or sting. The patches of rash may appear on different body parts, with variable duration from minutes to days, and typically ...
), lungs (
bronchiolitis obliterans Bronchiolitis obliterans (BO), also known as obliterative bronchiolitis, constrictive bronchiolitis and popcorn lung, is a disease that results in obstruction of the smallest airways of the lungs (bronchioles) due to inflammation. Symptoms inclu ...
), or kidneys (autoimmune
glomerulonephritis Glomerulonephritis (GN) is a term used to refer to several kidney diseases (usually affecting both kidneys). Many of the diseases are characterised by inflammation either of the glomeruli or of the small blood vessels in the kidneys, hence the ...
and
nephrotic syndrome Nephrotic syndrome is a collection of symptoms due to kidney damage. This includes proteinuria, protein in the urine, hypoalbuminemia, low blood albumin levels, hyperlipidemia, high blood lipids, and significant edema, swelling. Other symptoms ...
). Another sign are cancers such as Hodgkin and
non-Hodgkin lymphoma Non-Hodgkin lymphoma (NHL), also known as non-Hodgkin's lymphoma, is a group of blood cancers that includes all types of lymphomas except Hodgkin lymphomas. Symptoms include enlarged lymph nodes, fever, night sweats, weight loss, and tiredn ...
s, which appear to be increased, possibly due to
Epstein–Barr virus The Epstein–Barr virus (EBV), also known as human herpesvirus 4 (HHV-4), is one of the nine known Herpesviridae#Human herpesvirus types, human herpesvirus types in the Herpesviridae, herpes family, and is one of the most common viruses in ...
-encoded RNA-positivity. Some carcinomas may occur. Unaffected family members with genetic mutations are also at an increased risk of developing cancer.


Genetics

This condition is usually caused by mutations in the FAS gene. Rarely cases due to mutations in other genes including the FAS ligand gene have been reported.Magerus-Chatinet A, Stolzenberg MC, Lanzarotti N, Neven B, Daussy C, Picard C, Neveux N, Desai M, Rao M, Ghosh K, Madkaikar M, Fischer A, Rieux-Laucat F (2012) Autoimmune lymphoproliferative syndrome caused by a homozygous null FAS ligand (FASLG) mutation. J Allergy Clin Immunol The disease is inherited in an autosomal dominant manner, but it shows incomplete penetrance with up to 40% of people with a FAS mutation not showing symptoms. In 2024, a study highlighted the significance of novel genetic markers in the diagnosis and management of ALPS, emphasizing the role of next-generation sequencing in identifying mutations in genes beyond FAS, such as CASP10 and FASLG.


Diagnosis


Diagnostic algorithm

The old diagnostic criteria for the illness included: Chronic non-malignant lymphoproliferation, elevated peripheral blood DNTs and defective in vitro Fas mediated apoptosis. The new criteria require chronic non-malignant lymphoproliferation (over six months lymphadenopathy and/or splenomegaly), elevated peripheral blood DNTs. A primary accessory in diagnosis is defective in vitro Fas mediated apoptosis and somatic or
germline mutation A germline mutation, or germinal mutation, is any detectable variation within germ cells (cells that, when fully developed, become sperm and Egg cell, ova). Mutations in these cells are the only mutations that can be passed on to offspring, when e ...
in ALPS causative gene (FAS, FASL, CASP10). The secondary accessory in diagnosis are elevated biomarkers (plasma sFASL over 200 pg/ml, plasma IL-10 >20 pg/ml, plasma or serum vitamin B12 >1500 ng/L, Plasma IL-18 >500pg/ml) and immunohistochemical findings on biopsy consistent with ALPS as determined by an experienced hematopathologist. Another sign is autoimmune cytopenias and polyclonal hypergammaglobulinemia and a family history of ALPS or non-malignant lymphoproliferation. A definitive diagnosis is chronic non-malignant lymphoproliferation and/or elevated peripheral blood DNTs plus one primary accessory criterion. A probable diagnosis is the same but with one secondary accessory criterion.


Classification

2003 nomenclature * IA - Fas * IB -
Fas ligand Fas ligand (FasL, also known as CD95L or Apo-1L) is a type-II transmembrane protein in the tumor necrosis factor (TNF) superfamily. It binds to the Fas receptor (CD95) to induce apoptosis, and also activates non-apoptotic pathways such as NF-κB ...
* IIA -
Caspase 10 Caspase-10 is an enzyme that, in humans, is encoded by the CASP10 gene. This gene encodes a protein that is a member of the cysteine-aspartic acid protease (caspase) family. Sequential activation of caspases plays a central role in the execution ...
* IIB -
Caspase 8 Caspase-8 is a caspase protein, encoded by the ''CASP8'' gene. It most likely acts upon caspase-3. ''CASP8'' orthologs have been identified in numerous mammals for which complete genome data are available. These unique orthologs are also present ...
* III - unknown * IV - Neuroblastoma RAS viral oncogene homolog Revised nomenclature (2010) * ALPS-FAS: Fas. Germline FAS mutations. 70% of patients. Autosomal dominant. Dominant negative and haploinsufficient mutations described. * ALPS-sFAS: Fas. Somatic FAS mutations in DNT compartment. 10% of patients * ALPS-FASL:
Fas ligand Fas ligand (FasL, also known as CD95L or Apo-1L) is a type-II transmembrane protein in the tumor necrosis factor (TNF) superfamily. It binds to the Fas receptor (CD95) to induce apoptosis, and also activates non-apoptotic pathways such as NF-κB ...
. Germline FASL mutations. 3 reported cases * ALPS-CASP10:
Caspase 10 Caspase-10 is an enzyme that, in humans, is encoded by the CASP10 gene. This gene encodes a protein that is a member of the cysteine-aspartic acid protease (caspase) family. Sequential activation of caspases plays a central role in the execution ...
. Germline CASP10 mutation. 2% of patients * ALPS-U: Undefined. 20% of patients * CEDS: Caspase 8 deficiency state. No longer considered a subtype of ALPS but distinct disorder * RALD: NRAS,
KRAS ''KRAS'' ( Kirsten rat sarcoma virus) is a gene that provides instructions for making a protein called K-Ras, a part of the RAS/MAPK pathway. The protein relays signals from outside the cell to the cell's nucleus. These signals instruct the ce ...
. Somatic mutations in NRAS and KRAS in lymphocyte compartment. No longer considered a subtype of ALPS but distinct disease


Treatment

Treatment is most commonly directed at autoimmune disease and may be needed to treat bulky lymphoproliferation. First line therapies include
corticosteroids Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are invol ...
(very active but toxic with chronic use), and IVIgG, which are not as effective as in other immune cytopenia syndromes. Second line therapies include:
mycophenolate mofetil Mycophenolic acid is an immunosuppressant medication used to prevent rejection following organ transplantation and to treat autoimmune conditions such as Crohn's disease and lupus. Specifically it is used following kidney, heart, and live ...
(cellcept) which inactivates inosine monophosphate, most studied in clinical trials with responses varying (relapse, resolution, partial response). It does not affect lymphoproliferation or reduce DNTs, with no drug-drug interactions. This treatment is commonly used agent in patients who require chronic treatment based on tolerance and efficacy. It may cause hypogammaglobulinemia (transient) requiring IVIgG replacement.
Sirolimus Sirolimus, also known as rapamycin and sold under the brand name Rapamune among others, is a macrolide compound that is used to coat coronary stents, prevent organ transplant rejection, treat a rare lung disease called lymphangioleiomyomatosis ...
(rapamycin, rapamune) which is a mTOR (
mammalian target of rapamycin The mammalian target of sirolimus, rapamycin (mTOR), also referred to as the mechanistic target of rapamycin, and sometimes called FK506-binding protein 12-rapamycin-associated protein 1 (FRAP1), is a kinase that in humans is encoded by the ''M ...
) inhibitor can be active in most patients and can in some cases lead to complete or near-complete resolution of autoimmune disease (>90%) With this treatment most patients have complete resolution of lymphoproliferation, including lymphadenopathy and splenomegaly (>90%) and have elimination of peripheral blood DNTs. Sirolimus may not be as immune suppressive in normal lymphocytes as other agents. Some patients have had improvement in immune function with transition from cellcept to rapamycin and it has not been reported to cause hypogammaglobulinemia. Hypothetically, Sirolimus may have lower risk of secondary cancers as opposed to other immune suppressants and requires therapeutic drug monitoring. It is the second most commonly used agent in patients that require chronic therapy. It is mostly well tolerated (though side effects include mucositis, diarrhea, hyperlipidemia, delayed wound healing) with drug-drug interactions. It has better activity against autoimmune disease and lymphoproliferation than mycophenolate mofetil and other drugs; however, sirolimus requires therapeutic drug monitoring and can cause mucositis. The goal serum trough is 5–15 ng/ml with Sirolimus and PCP prophylaxis is usually not needed. Sirolimus is a mTOR inhibitor active against lymphomas, especially EBV+ lymphomas. However, a risk with any immunosuppressive agent in a pre-cancerous syndrome is decreased tumor immunosurvellence. Other treatments may include drugs like Fansidar, mercaptopurine: More commonly used in Europe. Another is
rituximab Rituximab, sold under the brand name Rituxan among others, is a monoclonal antibody medication used to treat certain autoimmune diseases and types of cancer. It is used for non-Hodgkin lymphoma, chronic lymphocytic leukemia (in children and ad ...
but this can cause protracted hypogammaglobulinemia and a
splenectomy A splenectomy is the surgical procedure that partially or completely removes the spleen. The spleen is an important organ in regard to immunological function due to its ability to efficiently destroy encapsulated bacteria. Therefore, removal of ...
but there is a >30% risk of pneumococcal sepsis even with vaccination and antibiotic prophylaxis


References


External links

{{Medical resources , DiseasesDB = 33425 , ICD10 = , ICD9 = {{ICD9, 279.41 , ICDO = , OMIM = 601859 , OMIM_mult = {{OMIM, 603909, , none , MedlinePlus = , eMedicineSubj = , eMedicineTopic = , MeshID = , Orphanet = 3261 Lymphocytic immune system disorders RASopathies Syndromes with tumors