Primary Immunodeficiency Flashcards
What can lead to immunodeficiency diseases?
Defects in one or more components of the immune system can lead to serious and often fatal disorders, which are collectively called immunodeficiency diseases.
What are the major consequences of immunodeficiency?
increased susceptibility to infection.
also susceptible to certain types of cancer.
Certain immunodeficiencies are associated with an increased incidence of autoimmunity.
What causes primary immunodeficiencies?
mainly caused by genetic aberrations
A smaller number of primary immunodeficiencies are caused by autoimmunity
Where may the abnormality be in Primary Immunodeficiency?
Components of the innate immune system
• Stages of lymphocyte development
• Responses of mature lymphocytes to antigenic stimulation
What is repeated infection with encapsulated bacteria a sign of?
a sign of defective antibody production.
What does an antibody deficiency lead to recurrent infections with?
leads to recurrent respiratory infection by pneumococcus or Haemophilus spp.
What infections may a reduced number of phagocytes lead to?
• Infections with staphylococci, gram-negative bacteria, and fungi
What do defects in T cells or macrophages predispose to infection with?
intracellular organisms such as protozoa, viruses, and intracellular bacteria, including mycobacteria.
What is reactivation of latent herpesvirus infection linked to?
T-cell
immunodeficiency.
What is non-Hodgkin lymphoma (Epstein-Barr virus [EBV] characteristic of?
T-cell dysfunction.
What is a gene mutation?
A gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people.
What do polymorphisms involve?
Polymorphism involves one of two or more variants of a particular DNA sequence. The most common type of polymorphism involves variation at a single base pair. Polymorphisms can also be much larger in size and involve long stretches of DNA.
What are polygenic disorders?
These are disorders caused by the combined action of more than one gene.
• Polygenic disorders of the immune system are relatively common and affect mainly antibodies.
What is the treatment for SCID?
Stem cell transplant can cure SCID but it has to be done quickly. If it is performed very soon after birth, 90% infants survive; if it is delayed for a few months, only 50% infants survive the transplant procedure.
What are genetic polymorphisms?
Genetic polymorphisms are alleles (different forms) of the same gene occurring at a single locus in at least 1% of the population.
What is mannan-binding lectin?
Mannan-binding lectin (MBL) is a collagen-like protein that binds sugars in bacterial cell walls and activates the classic complement pathway.
What are the common polgenic disorders?
CVID
IgA deficiency
Specific antibody deficiency
What is the most common primary immunodeficiency requiring treatment
CVID
Describe antibody and lymphocyte levels in CVID.
Patients have low levels of total IgG. Levels of IgA and IgM and numbers of B and T cells are variable.
Describe how CVID may present.
CVID causes recurrent respiratory tract infections.
Infections that involve the gut, skin, and nervous system also occur. Autoimmunity is common in CVID.
Many patients have a history of other affected family members or of consanguinity, which suggests autosomal-recessive inheritance.
What organisms are common in infections in those with polygenic immunodeficiencies?
pneumococcus or Haemophilus
What infection is often found in autoimmune polyendocrinopathy candidiasis ectodermal dysplasia (APECED)?
severe recurrent Candida infection.
Mutations in what gene cause APECED?
AIRE gene
What signs in the first week of life suggest SCID?
Unusual or recurrent infection
• Diarrhoea
• Unusual rashes
What is used to measure lymphocyte count in SCID?
flow cytometry
When do most forms of antibody deficiency present?
Adulthood
What pattern of infection is commonly seen in CVID?
Recurrent resp infections
Describe the use of gene therapy in the treatment of SCID
Gene therapy uses recombinant technology to correct the genetic defect in the patient’s own stem cells, which can then reconstitute the immune system.
used in patients with SCID for whom no suitable stem cell donor was available.
What steps are taken to avoiding infection in SCID?
- Avoiding live vaccines (eg, measles, mumps, rubella, polio)
- Prophylaxis against opportunist infections such as Pneumocystis jiroveci.
When is SCT most successful in SCID?
within a few weeks of birth, before the infant has developed any infections.
What is the common defect in chromic granulomatous disease?
Phagocyte
