Flashcards in Immunology Deck (41):
What are SPUR features?
(Clinical features suggestive of immunodeficiency)
Commonest form of severe combined immunodeficiency
Underlying immuno-pathophysiology of X-linked SCID
IL-2 receptor mutation; inability to produce T cells and NK cells
Clinical presentation of X-linked SCID (4)
Unwell by 3 months old
Failure to thrive
Infections of all types
Organised collection of activated macrophages and lymphocytes
Key mediators in granuloma formation (3)
IL-12 released by macrophages
gIFN produced by T-cells
Granulomatous conditions (3)
Silicosis and other dust diseases
Manifestations of antibody dysfunction (2)
Recurrent bacterial infections
Antibody-mediated immune diseases
Examples of antibody deficiencies (2)
Common variable immune deficiency (CVID)
Selective IgA deficiency
What is Bruton's agammaglobulinaemia?
An X-linked primary deficiency of antibody production where patients have no B cells
Causes of secondary hypogammaglobulinaemia (2)
Protein loss e.g. nephrotic syndrome
Lymphoproliferative disease e.g. myeloma
Type I hypersensitivity
IgE-mediated e.g. anaphylaxis
Type II hypersensitivity
Antibody-mediated direct cell-killing, e.g. autoimmune haemolytic anaemia
Type III hypersensitivity
Immune complex-mediated e.g. SLE
Type IV hypersensitivity
Delayed type, T-cell mediated e.g. graft versus host disease
How can antibody lead to direct cell killing? (3)
Activation of complement via the classical pathway leading to:
a) opsonization (optimises phagocytosis)
b) formation of the membrane attack complex, causing lysis
c) recruitment of other immune cells
What activates the alternative complement pathway?
LPS on microbial surfaces
What does complement deficiency predispose to?
Bacterial infection especially meningitis
What types of cell do NK cells target? (2)
Cells which lack MHC molecules on surface; especially viruses and cancer cells
What are Toll-like receptors? (2)
Receptors on phagocytes providing innate recognition of pathogens; activation leads to release of pro-inflammatory cytokines
What are adalimumab and etanercept? What is their mechanism of action?
TNF-inhibitors used in chronic inflammatory conditions such as rheumatoid arthritis and Crohns disease. Inhibit TNF, thus preventing release of pro-inflammatory cytokines
What is the main risk/side effect of adalimumab?
Reactivation of tuberculosis
Mechanism of hyperacute graft rejection
Type II hypersensitivity- pre-formed antibody and complement activation
Timescale and mechanism of acute graft rejection
5-30 days; Type IV hypersensitivity (T cells)
What is the drug target of cyclosporin?
Calcineurin. Inhibition helps prevent lymphocyte activation
What is the first antibody to be produced in the immune response?
Vaccination stimulates the production of...
Memory T cells
Main types of vaccine
Live attenuated vaccines
Disadvantages of inactivated vaccines (2)
Require multiple/booster injections
Require adjuvants to boost immunogenecity
Constituents of the 5-in-1 vaccine
What type of vaccine is the 5-in-1? When is this given?
Inactivated vaccines. 8, 12 and 16 weeks
(at 3 years and 4 months, given again minus HiB)
(at 14 years given again minus HiB and pertussis)
Advantages of live attenuated vaccines (3)
Elicits antibody and T cell responses
Gives strong response
Usually only one dose required
Example of a live attenuated vaccine given at one year
How does the lectin pathway of complement work?
Proteins such as MBL coat sugars on the surface of bacteria, thus activating the complement cascade and helping the bacteria be eliminated
Why is the "5-in-1" vaccine given at 3 months, 4 months and 3 years?
In order to boost immunity- 5-in-1 vaccine are inactivated and hence have poor immunogenecity
How do live attenuated vaccines work?
pathogen is made virulent, but is still live and replicating, and hence is a good immunogen
Which antibody is mostly generated during secondary exposure to a pathogen?
(there is also smaller levels of IgM)
How does IgA selective deficiency usually present?
Most are asymptomatic and will not be detected
The main risks of TNF inhbitors is are...
Granulomatous infections, fungal infections
Anti-TNFs represent a form of...