Common variable immunodeficiency

Common variable immunodeficiency
ICD-10	D83
ICD-9	279.06
OMIM	240500
DiseasesDB	3274
MeSH	D017074

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]

Synonyms and keywords: CVID; common variable hypogammaglobulinaemia; non-familial hypogammaglobulinaemia; acquired hypogammaglobulinemia; immunodeficiency, common variable; late-onset immunoglobulin deficiency

Overview

Common variable immunodeficiency (CVID) is a primary immunodeficiency disorder. It is the most common form of severe antibody deficiency affecting both children and adults. The characteristic immune defect in CVID is impaired B cell differentiation with defective production of immunoglobulin. CVID is defined by low total serum concentrations of immunoglobulin G (IgG), as well as low immunoglobulin A (IgA) and/or immunoglobulin M (IgM), poor or absent response to immunization, and the absence of any other defined immunodeficiency state.

Most patients are diagnosed between the ages of 20 and 40 years. Delayed recognition is common.

Bacterial infections of the sinopulmonary tract, particularly sinusitis and pneumonia, are experienced by most patients with CVID (table 1). Opportunistic and unusual infections are uncommon, but do occur.

In addition to recurrent infections, patients with CVID have evidence of immune dysregulation leading to autoimmunity, a variety of inflammatory disorders, and malignant disease. Patients may suffer from chronic lung disease, gastrointestinal and liver disorders, granulomatous infiltrations, lymphoid hyperplasia, splenomegaly, or malignancy.

Various forms of primary and secondary hypogammaglobulinemia must be excluded before the diagnosis of CVID can be assigned.The diagnosis of CVID requires a suggestive clinical history, a reduced total serum concentration of IgG, plus low IgA or IgM, and poor responses to both protein- and polysaccharide-based vaccines.

Historical Perspective

Charles Janeway et al (1953) is generally credited with the description of the first case of CVID.

Classification

Common variable immunodeficiency (CVID) is a heterogeneous immune disorder characterized by recurrent sinopulmonary infections, autoimmune disorders, granulomatous disease, and an enhanced risk of malignancy

A phenotypic approach to categorizing CVID has been proposed, based upon the type of complications the patient develops. This arose from an analysis of the European Common Variable Immunodeficiency Disorders registry, in which 334 patients with CVID were followed for an average of 26 years . Five phenotypic categories were proposed:

1. Patients with no complications
2. Patients with autoimmune disease
3. Patients with lymphocytic organ infiltration (ie, lymphocytic enteropathy, granulomas, unexplained hepatomegaly, persistent lymphadenopathy, splenomegaly, and/or lymphoid interstitial pneumonitis)
4. Patients with predominant enteropathy
5. Patients with lymphoid malignancy

Type	Gene	Immunoglobulin Deficiency	Phenotype
ICOS deficiency	ICOS	Low IgG and IgA	Recurrent infections, autoimmunity, gastroenteritis.
CD19 deficiency	CD19	Low IgG and IgA	Recurrent infections. May be associated with glomerulonephritis.
CD81 deficiency	CD81	Low IgG, low or normal IgA and IgM	Recurrent infections. May be associated with glomerulonephritis.
CD20 deficiency	CD20	Low IgG, normal or elevated IgM, and IgA	Recurrent infections.
CD21 deficiency	CD21	Low IgG; impaired antipneumococcal response	Recurrent infections.
TACI deficiency	TNFRSF13B	Low IgG and IgA and/or IgM	Variable clinical expression
BAFF-receptor deficiency	TNFRSF13C	Low IgG and IgM	Variable clinical expression
TWEAK deficiency	TWEAK	Low IgM and IgA; lack of antipneumococcal antibody	Recurrent infections such as Pneumonia, bacterial infections, warts; and thrombocytopenia; neutropenia
NF-kappa-B2 deficiency	NFKB2	Low IgG and IgA and IgM; very low B cells in some	Recurrent infections; adrenal insufficiency; ACTH deficiency; alopecia
NF-kappa-B1 deficiency	NFKB1	Low IgG and IgA and IgM; low B cells in some	Recurrent infections
IKAROS	IKZF1	Low IgG and IgA and IgM, very low B cells	Recurrent infections

Pathophysiology

CVID is believed to be a genetically determined primary immune defect; however, the underlying causes are different. The result of these defects is that the patient doesn't produce sufficient antibodies in response to exposure to pathogens. As a result, the patient's immune system fails to protect them against common bacterial and viral (and occasionally parasitic and protozoan) infections. The net result is that the patient is susceptible to illness. Both parts of the immune system (the cellular and humoral system) are affected, hence its classification as a combined immunodeficiency.

CVID appears to include a number of defects, some of which have been identified. For the majority, the genetic causes are still unknown. It is possible that environmental agents provoke the immune defect, due to genetic predisposition, but this has not been clarified.

Differentiating Common Variable Immunodeficiency from other Diseases

CVID should be differentiated from the following diseases:

• Bruton agammaglobulinemia(X-linked agammaglobulinaemia)
• Severe combined immunodeficiency(SCID)

Epidemiology and Demographics

Prevalence

CVID has an estimated prevalence ranging from a low of 2 per 100,000 to a high of 4 per 100,000 with an average of 3 per 100,000.

Age

• The typical patient is between 20 and 40 years age.
• About 20% of patients are diagnosed in childhood.

Gender

Gender is not associated with an increased risk of common variable immunodeficiency.

Race

Race is not associated with an increased risk of common variable immunodeficiency.

Natural History, Complications and Prognosis

Natural History

All patients have acute and recurrent infections because of the level of immunodeficiency in CVID.

Complications

3 complications are possible in CVID. They include:

• Recurrent infections
• Autoimmune phenomena - Vitiligo, autoimmune hepatitis, primary biliary cirrhosis, hemolytic anemia
• Malignancy - Lymphomas, gastric cancer, malignant melanoma
• Rheumatoid arthritis
• Vitiligo
• Thrombocytopenia
• Neutropenia
• Hemolytic anemia
• Pernicious anemia
• Malabsorption
• Autoimmune hepatitis
• Primary biliary cirrhosis
• Atrophic gastritis
• Inflammatory bowel disease

Diagnosis

History and Symptoms

Symptoms of CVID are:

• Polyarthritis, or joint pain, spread across most joints, but specifically fingers, wrists, elbows, toes, ankles and knees
• Chronic infections (most common symptom) specifically upper respiratory tract infection - e.g. bronchitis, sinusitis which respond to antibiotics but return or reoccur. Common infective organisms include:
  • Haemophilus influenzae
  • Streptococcus pneumoniae
  • Moraxella catarrhalis
  • Staphylococcus aureus
• Viral infections that usually respond to antivirals, (URTIs), sinusitis, tonsilitis, epiglottitis, dermatological abscesses/boils (often, but not exclusively, facial and axillary), pneumonia, bronchitis, pleurisy, stomach/intestinal infections, colds, influenza, shingles, conjunctivitis
• Tiredness
• Shortness of breath - due to bronchiectasis (lung tissue damage as a result of repeated chest infections)
• Patients may lose weight
• Children may show a "failure to thrive" - they may be underweight and underdeveloped compared with "normal" peers
• Diarrhoea and malabsorption - due to villous atrophy in the small intestine, which can resemble coeliac disease, intestinal infections, including protozoan and parasitic infections, bacterial overgrowth of the intestine
• Increased incidence of inflammatory bowel disease
• Abdominal pain, bloating, nausea, vomiting, diarrhea, weight loss.

Physical Examination

Head

• Swelling of the lymph glands - lymphadenopathy

Abdomen

• Enlarged spleen

Laboratory Findings

• Complete blood count and differential count - lymphocytopenia
• Blood culture
• Hypogammaglobulinemia, or low levels of immunoglobulin G (IgG), IgA and/or IgM. Lack of normal levels of antibody in the serum is part of the diagnosis
• Poor titer levels in response to vaccination. Responsiveness may be tested after administration of polysaccharide and non-polysaccharide coated pathogens (e.g. streptococci and tetanus respectively)

Diagnosis is often delayed; and diagnosis is often made in the second or third decade of life after referral to an immunologist.

As with several other immune cell disorders, CVID may predispose to lymphoma or possibly stomach cancer. There also appears to be a predilection for autoimmune diseases, with a risk of up to 25%. Autoimmune destruction of platelets or red blood cells are the commonest of these.

Treatment

Medical Therapy

Treatment usually consists of immunoglobulin therapy, which is an injection of human antibodies harvested from blood donations:

• Intravenous immunoglobulin (IVIG, most common treatment)
• Subcutaneous immunoglobulin G (SCIG, relatively new therapy)
• Intramuscular immunglobulin (IMIG, less effective, painful).

This is not a cure, but it strengthens immunity by ensuring that the patient has "normal" levels of antibodies, which helps to prevent recurrent upper respiratory infections.

IG therapy can't be used if the patient has anti-IgA antibodies but in this case, products low in IgA can be used; subcutaneous delivery also is a means of permitting such patients to have adequate antibody replacement.

IVIG treatment can be received by patients with a complete IgA deficiency if the IgA is completely removed from the treatment.

Some CVID patients may experience reactions to IG therapies; reactions may include:

• Anaphylactic shock (very rare)
• Hives (rare)
• Difficulty breathing
• Headache (relatively common, may be relieved by an antihistamine, paracetamol / acetaminophen, or an anti-inflammatory (naproxen, advil, aspirin)
• Nausea (common)
• Fever (common)
• Aseptic meningitis (rare)
• Severe fatigue
• Muscle aches and pain, or joint pain
• Thrombotic events (rare)

Patients should not receive therapy if they are fighting an active infection as this increases the risk of reaction. Also, patients changing from one brand of product to another may be at higher risk of reaction for the first couple of treatments on the new brand.

Reactions can be minimised by taking an antihistamine and/or hydrocortisone and some paracetamol/acetaminophen/anti-inflammatory (naproxen, advil, aspirin) prior to treatment; patients should also be thoroughly hydrated and continue to drink water before, after and during treatment (if possible).

External links

• Primary Immunodeficiency Association (UK)
• Immune Deficiency Foundation (US)
• Immune Deficiencies Foundation of Australia
• Immune Deficiencies Foundation of New Zealand
• IPOPI (International Patient Organisation for Patients with Primary Immunodeficiency)
• Canadian Immunodeficiencies Patient Organization (Canada)

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