Immunology Flashcards
What are SPUR features?
Serious infections Persistent infections Unusual infections Recurrent infections (Clinical features suggestive of immunodeficiency)
Commonest form of severe combined immunodeficiency
X-linked SCID
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
Persistent diarrhoea
Failure to thrive
Infections of all types
Organised collection of activated macrophages and lymphocytes
Granuloma
Key mediators in granuloma formation (3)
IL-12 released by macrophages
gIFN produced by T-cells
TNF
Granulomatous conditions (3)
Sarcoidosis
Tuberculosis
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)
