Primary immunodeficiency Flashcards
What is the precursor for neutrophils?
Pre-myeloid cells
What is the precursor for T-cells (thymus) and B cells (bone marrow?
Lymphocyte committed stem cells
Antibodies acting within specific immunity mainly target which pathogens?
Pyogenic bacteria e.g. staph, strep pneumoniae, haem influenzae
Enteroviruses, polio and ECHO
Cellular immunity is mainly mediated by what kinds of cells?
T cells and antigen presenting cells
Cellular immunity (specific immunity) mainly acts against which pathogens?
Viruses
Fungi (candida, aspergillus, pneumocystis)
Bacteria
Protozoa
The complement system (non-specific immunity) acts against which kinds of pathogens?
Pyogenic bacteria
Neisseria
Phagocytes (non-specific immunity) act against what kinds of pathogens?
Staphylococci
Gram-negative
Fungi (candida, aspergillus)
What provides antibody immunity to babies for the first 6 months?
Maternal transferred IgG
What is the main cause of primary immunodeficiency?
Genetic aberrations
What is the main consequence of immunodeficiency?
Increased susceptibility to infection
Where could primary immunodeficiency defects be?
Innate immune system
Stages of lymphocyte production
Mature lymphocyte response to antigens
What are some indicators for degree and cause of immunodeficiency?
Stage of immune cell production affected
Type of opportunistic infection
What would a severe invasive fungal infection suggest about the immunodeficiency?
Phagocytes or TH17 affected
What part of immunity is affected by neisseria infection?
Complement defects
Which antibodies should be tested for in recurrent resp infection by pneumococcus and haemophilus spp?
IgG
IgA
What kind of immunity is associated with staph, gram-negative bacteria and fungi infection?
Phagocyte deficiency or defect
What kind of infection do T cell defects predispose us to?
Intracellular organisms like protozoa, viruses, intracellular bacteria (mycobacteria)
TB can cause lung infection in the immunocompetent but when can it affect a patient outside the lungs?
Mild T-cell immunodeficiency
Severe immunodeficiency also predisposes us to low virulence mycobacteria which wouldn’t usually cause infection
Which pathogen causes TB?
Mycobacterium tuberculosis
How is reactivation of latent infections linked to immunodeficiency?
Reactivation of herpes virus, often in the form of cold sores, may suggest mild immunodeficiency
Recurrent candida infection suggest what kind of defect?
TH17 pathway
Phagocyte defect
HIV positive patients are more susceptible to what kind of cancer?
Kaposi sarcoma
Epstein-Barr virus can cause what kind of cancer?
Non-Hodgkin lymphoma
What are some different kinds of genetic causes for primary immunodeficiency?
Polymorphism
Mutation
Polygenic disorders
How are severe combined immune deficiency cured?
Stem cell transplant
Must be done quickly
Infants born with SCID must be treated ASAP or survival declines
What is HLA?
Human leukocyte antigen
Regulate immune system
If HLA can’t bind viral peptides then there are bad infectious outcomes for the affected
What is CVID?
Common variable immunodeficiency
Polygenic disorder
Includes IgA, IgG, IgM specific antibody deficiency
What does CVID do?
Commonly recurrent resp tract infections
Also may involved gut, skin, nervous system
Where is the defect in Wilkott-Aldrich syndrome?
T and B cells
Affects actin cytoskeleton
Where is the defect in DiGeorge syndrome?
T cells
Affects TH17 responses
Where is the defect in HLA?
Antigen presentation
What are some features of clinical presentation of SCID?
Defective T and B cells
Unusual or recurrent infection
Diarrhoea
Unusual rashes
What are some test results we could expect in SCID
Very low lymphocyte count
What are some useful tests for checking immunodeficiency?
IgG, IgA, IgM should be measured
If these tests are normal it is important to check there are no problems with complement neutrophil function
What is the main aim in treating immunodeficiency?
Prevent infection
How are immunodeficiencies treated?
Prophylactic antibiotics nay be adequate in mild cases
Immunoglobulin replacement therapy in more severe cases
Gene therapy
What are the benefits of immunoglobulin replacement therapy?
Antibodies against wide range of pathogens
Ig pooled from thousands of normal donors
Ig replacement can be given IV or subcutaneously
Plasma screened for HIV, Hep C and Hep B
How is gene therapy used?
Recombinant technology used to correct genetic defect in stem cells which then reconstitute the immune system
