Primary immunodeficiency Flashcards
Briefly describe immune cell development
3 different types of immune cells that develop from pluriportent stem cells
- Pre-myeloid cells (precursors for neutrophils)
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Lymphocyte-committed stem cell (become T (develop in thymus) and B cells (develop in marrow)
- Effector and suppressor T- cells
- CD4 = Th1, Th2, Th17 and regulatory T cells
- CD8 = regulatory ones too
- B-cells are responsible for producing antibodies – once they start secreting antibodies they become plasma cells
- Effector and suppressor T- cells
- Pre-monocyte – become macrophages
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What is the adaptive/acquired immunity?
Immunity that occurs after exposure to an antigen either from a pathogen or a vaccination.
It involves 2 things:
- Antibodies produced by B cells and the cellular immunity through t-cells and antigen presenting cells
- Cellular immunity through T cells and antigen presenting cells
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What do antibodies mainly fight against?
- Pyogenic bacteria such as staphylococci, staph pneumoniae Haemophilus influenzae
- Some viruses such as enteroviruses
What is the innate/non-specific immunity?
The body’s first line of defense against germs entering the body. It responds in the same way to all germs and foreign substances hence why it is termed ‘non-specific’
It does this through:
- the complement system
- phagocytes
What do phagocytes fight mainly? (2)
- Bacteria - staphylococci, gram negative
- Fungi - aspergillus, candida
What does the complement system fight mainly? (2)
Pyogenic bacteria
Neisseria - meningitis
What bacteria do T-cells fight?
- Viruses - measles, herpes zoster
- Fungi - candida, aspergillus
- Bacteria - myobacteria, listeria
- Protozoa - cryptosporidium
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What is immunodeficiency?
It can be classified into 2 groups, what are these?
Defects in one or more components of the immune system can lead to serious and often fatal disorders, which are collectively called immunodeficiency diseases.
- Primary, or congenital immunodeficiencies
- Secondary, or acquired immunodeficiencies
What is meant by the effector and suppressor parts of the immune system?
- Effector part of immune system – counteracts infectious organisms and cancers
- Suppressor/regulatory part of immune system – keeps immune system in check – if the immunodeficiency affects these regulatory systems then they could be associated with autoimmunity
What is the main consequence of immunodeficiency?
Increased susceptibility to infection
- Patients with immunodeficiencies are also susceptible to certain types of cancer - failure of effector part of immune system
- Certain immunodeficiencies are associated with an increased incidence of autoimmunity - failure of suppressor part of immune system
What is primary immunodeficiency?
- A group of genetic, congenital disorders
- Part of the immune system is either missing or functioning abnormally due to inherited mutations
- A smaller number of primary immunodeficiencies are caused by autoimmunity.
- It predisposes the person to infections (recurrent, unusal and difficult to treat) and tumours
What abnormalities arise in the immune system as a result of primary immunodeficiency?
- Components of the innate immune system
- Stages of lymphocyte development
- Responses of mature lymphocytes to antigenic stimulation
Does it matter at which stage of lymphocyte development a defect occurs?
Yes. Defects in development of lymphocytes can occur at any stage but the earlier the defect in the development process the more severe the disease is:
- If the defect happens very early on then it affects both B and T cell development
- Could be later when cells have committed to either becoming B or T cells, can affect one or the other
- Or even later, the defect could be in a cell’s function after normal development
Look
Remember the increased susceptibility to infection depends on the component of the immune system that is defective.
- Different parts of the immune system fight different microorganisms
- The type of opportunist infection present also gives clues to the degree and cause of immunodeficiency
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What is one sign that a patient’s infection is being caused by defective antibody production?
Repeated infection with incapsulated bacteria