Common variable immunodeficiency
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Common Variable Immunodeficienc
yFatima Al-Awadh
Objectives• Describe the immune system.• Mention the ways of activating B lymphocytes.• Recognize the types of antibodies.• Describe the Isotype switching.• Define Immunodeficiency.• Define the common variable immunodeficiency.• Mention causes, pathophysiology, Signs &
Symptoms, Complications, Diagnosis, Differential diagnosis, Management and Prevention.
The immune system• Immunity is defined as resistance to disease,
specifically infectious disease. • The collection of cells, tissues, and molecules that
mediate resistance to infections is called the immune system, and the coordinated reaction of these cells and molecules to infectious microbes is the immune response.
• Immunology is the study of the immune system and its responses to invading pathogens.
• The physiologic function of the immune system is to prevent infections and to eradicate established infections.
The components of the immune system
Ways to Activate B Lymphocytes
Complement activationHelper T lymphocyte activation
1. Complement Activation
2. Helper T Lymphocyte Activation
Antibodies
StructureTypes
Isotype Switching
Structure of Antibody
Types of Antibodies
Isotype Switching
ImmunodeficiencyDefects in the development and
functions of the immune system result in
Increased susceptibility to infections
reactivation of latent infections
increased incidence of certain cancers
Immunodeficiency• Disorders caused by defective immunity are
called immunodeficiency diseases.• Some may result from genetic abnormalities in
one or more components of the immune system; these are called congenital (or primary) immunodeficiencies.
• Other defects may result from infections, nutritional abnormalities, or medical treatments; these are called acquired (or secondary) immunodeficiencies.
The Common variable Immunodeficiency
• Common variable immunodeficiency is a heterogeneous group of disorders that represent a common form of primary immunodeficiency.
• These disorders are characterized by poor antibody responses to infections and reduced serum levels of IgG, IgA, and often IgM.
Genetic Causes• Due to the unclear genetic nature of CVID, a clear
pattern of inheritance has not been defined.• In some instances, more than one family
members are deficient in one or more types of immunoglobulins
• CVID is autosomal recessive.
Gene Mutations in CVID
inducible co-stimulatory
(ICOS)
protein on B-cells (CD19)
Mutations in a cell
receptor (TACI)
Causes• The underlying causes of common variable
disease are poorly understood but include defects in B call maturation and activation.
• Some patients have mutations in genes encoding receptors for B cell growth factors or co-stimulators involved in T cell-B cell interactions.
PathophysiologyC
han
ges
in t
he
hu
mora
l re
spon
se • Failed B cell differentiation with impaired secretion of immunoglobulins
Ch
an
ges
in t
he
cell
-med
iate
d
resp
on
se• T cell abnormalities present as well, therefore, this is a global immune dysfunction disease
Signs & Symptoms• frequent and chronic bacterial, viral or fungal
infections (bronchitis, pneumonia, ear or skin infections etc.)
• chronic sinusitis or upper respiratory damage, bronchiectasis
• fatigue• lymph gland enlargement• joint pain or arthritis (may be due to infection)• hair loss• infections or disorders of the digestive tract,
diarrhea• anemia• spleen enlargement
Complications
lymphoma autoimmune disease
premature death
Diagnosis• Testing is done by measuring immune globulin
levels in the blood. Supportive tests such as antibody response tests and CT scan of sinus or lungs may also be utilized.
• CVID often goes undiagnosed until symptoms are more profound, in the second to fourth decade of life.
Differential DiagnosisPrimary hypogammaglobulinemia:
• X-linked agammaglobulinemia• SCID: atypical infections, T cell defects, or dysmorphic features• Hyper-IgM syndrome: neutropenia, with normal or elevated IgM and absent IgG
Secondary hypogammaglobulinemia:• Decreased production
o Malignancy: thymoma, CLL, lymphomao Drugs: immunosuppresants, antiepilepticso Viral infections: EBV, HIV, CMV, parvovirus B19o Systemic illnesses causing bone marrow suppression
• Increased losso Protein-losing enteropathieso Nephrotic syndromeo Burn victims
Management• IVIG is the
mainstay of treatment.
• Treatment of infections.
• Surveillance for autoimmunity & malignancy.
Prevention• Inheritance patterns vary among
patients and are not present in most patients, making this disorder impossible to prevent.
References• Basic Immunology, Abbas 3th ed.• http://
www.immunedisease.com/pdf/common-variable-immunodeficiency-cvid.pdf
• http://medicine.ucsf.edu/education/resed/Chiefs_cover_sheets/CVID.pdf
• http://www.info4pi.org/aboutPI/index.cfm?section=aboutPI&content=syndromes&area=4&CFID=2813523&CFTOKEN=3
• http://voices.yahoo.com/common-variable-immune-deficiency-cvid-symptoms-diagnosis-424431.html
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