Clinical Sciences Flashcards
On which chromosomes are the genes which encode for HLA proteins?
6
What is the difference between MHC Class I and Class II?
Class 1 = Surface of all cells, Allow for Cytotoxic/NK T cells to rcognisde viral/tumour antigens produced within the cell, CD8
Class 2 = Surface of APCs, involved in antigen presenting of extracellular pathogens, CD4
Which diseases are most associated with HLA B27?
AS
Post-gonococcal Arthritis
Acute Anterior Uveitis
Reactive Arthritis
Which disease are most associated with HLA DR2?
Narcolepsy
Goodpasture’s
Which diseases are most associated with HLA DR3?
Autoimmune hepatitis
PBC
T1DM
Dermatitis Herpetiformis
Coeliac
Sjogren’s
Which diseases are most associated with HLA DR 4?
RA
T1DM
Which disease is most associated with HLA DR3 and 4 together?
T1DM
Which disease is most associated with HLA B47?
21-hydroxylase deficiency
Which diseases are most associated with HLA A3?
Haemochromatosis
Which HLA is associated with Behcet’s?
HLA-B5
What is Felty’s Syndrome?
Triad of:
RA
Splenomegaly
Neutropaenia
Highly associated with HLA DR4
What are CD1 molecules?
HLA molecules with present lipid molecules
What are CD2 molecules?
Found on thymocytes, T cells and some NK cells
Act as a ligand for CD58 and CD59 - signal transduction and cell adhesion
What are CD3 molecules?
The signalling component of the T-Cell Receptor
What are CD4 molecules?
Co-receptor for MHC Class I
Which receptors are used by HIV units to enter T Cells?
CD4
What are CD8 molecules?
Co_receptor for HLA Class I
Also found on a subset of myeloid dendritic cells.
What are type I hypersensitivity reactions?
IgE mediated anaphylactic reaction provoked by re-exposure to an allergen. Allergies, Hayfever etc = type 1
Which anaphylactoid reactions aren’t IgE mediated?
NSAIDs, IV Contrast, Opioids, Exercise-allergy
How do NSAIDs cause anaphylactoid reactions if not IgE mediated?
COX-1 inhibition -> Reduced prostanglandins, more leukotrienes = bronchoconstriciton, urticaria and pruritus
What are Type II hypersensitivity reactions?
IgG/IgM Mediated
Antibody reacts with cell/matrix associated self-antigen.
Leads to tissue damage/receptor blockade/receptor activation
Which test would be positive in autoimmune haemolytic anaemias and which HS type are they?
Direct Coombs
Type II
What are type III hypersensitivity reactions?
IgG/IgM immune complex mediated (Ab vs Soluble Ag)
List 4 disease caused by Type III HS reactions
Mixed essential Cryoglobulinaemia
Serum Sickness
Polyarteritis Nodosa
SLE
What are Type IV hypersensitivity reactions?
T-Cell mediated
Delayed
List 4 diseases caused by Type IV hypersensitivity reactions
T1DM
MS
RA
Crohn’s
What is Type V hypersensitivity?
IgG mediated tissue damage
Graves’, MG
What are skin prick tests used for?
Food Allergies
Pollen
Insect venom (bee stings etc.)
Take 15 mins
Histamine pos. control & H2O neg. control used alongside ?allergen
What is RAST?
Radioallergosorbent testins
Grades level of IgE response to allergens
Food, Pollen, Insect venom
Graded 0 (negative) to 6 (strongly positive).
What is skin patch testing used for?
Contact dermatitis
What are monocytes
APCs produced in BM
Migrate via blood to tissues where they differentiate to macrophages
What roles do IgG antibodies have?
Activate Classical complement pathway
Bind to macrophages & neutrophils for enhanced phagocytosis
Bind to NK Cells for antibody-dependent cytotoxicity
Which antibodies can cross the placenta?
IgG
What roles do IgA antibodies have?
Blocks attachment of bacteria/viruses to mucous membranes preventing internalisation
Exist in bodily secretions
Activates Alternative complement pathway