Immune System Flashcards
Natural Killer cells
Carry marker CD 16
Kill cells with downregulated MHC class 1 and stress related Fc fragments-virus infected cells and tumour related cells
Release perforins which lyse cells
Respond to IFN and IL-2
MHC Class 1, 2 and 3 locations
MHC 1: All nucleated and platelet cells
Coded by HLA A, B and C
MHC 2: Macrophages, activated T cells, B cells and dendritic cells
MHC 3: Complement
Antigen presentation
MHC Class 1: Endogenous protein such as viral protein is presented by MHC class 1 and detected by CD 8+ T Cells
MHC Class 2: Exogenous protein such as phagocytosed material is presented by MHC class 2 and detected by CD 4+ T helper Cells
T cells, TCR and MHC
T cells recognise MHC via their own TCR
CD 4 T helper cells recognise MHC 2 and CD8 T cells recognise MHC 1
CD8 T cells
MHC Class 1 –> CD 8 T cells
Kill cells and leave memory cells behind
CD4 T Helper Cells
Recognise MHC Class 2:
IFN g—>macrophages
IL-2—>T cell and B cell proliferation
IL-4—>promotes CD4 T cells and B cell proliferation
IL-5—>activation of eosinophils
IL-6—>T cell and B cell differentiation
IL-10—>Suppresses macrophage cytokine production
IL-12—>Promotes cytotoxic action of T and B cells
B cells
B cells detect antigen via B cell receptor and then morph into plasma cells which secrete immunoglobulins
CD4 T helper cells (activated by MHC class II) promote Ig production
All Ig have similar structure except IgM
Hypersensitivity reactions Type I-V
Type 1: Immediate/Anaphylaxic Ig E
Asthma, anaphylaxis
Type 2: Ig to ag Cytotoxic
Drug reaction, autoimmune thrombocytopenia, transfusion reaction
Type 3: Ig/Ag Immune complexes
SLE, glomerulonephritis
Type 4: CD 8 T Cells
TB mantoux, transplant rejection
Type 5: Anti-receptor ab’s
Grave’s myasthenia gravis
Autoantibodies
ANA ---> SLE, Sjogrens Anti-Ro ---> Sjogrens Anti-La ---> Sjogrens Anti-centromere ---> CREST Anti-Scl70 ---> Scleroderma
MHC Class 1 and 2 diseases
MHC 1: More in men
- HLA b27 (Ankylosing spondylitis and Reiter’s syndrome)
- HLA Cw6 (Psoriasis)
MHC Class II: More in women
- HLA-DR5 (Pernicious anaemia and Hashimoto’s)
- Rheumatoid Arthritis (HLA-DR4)
Immune deficiency (6)
IgA Deficiency Common variable immunodeficiency Brutons' x-linked agammaglobulinaemia Subacute combined immunodeficency Di-George's syndrome Complement factor deficiency
IgA Deficiency
Congenital or acquired (post virus)
Recurrent pulmonary/Gi infections
Usually asymptomatic
Common variable immunodeficiency
Congenital
Hypogammaglobulinaemia particularly IgG
Recurrent pyogenic infections after first decade
Autoimmune disease and lymphoid malignancy
Brutons’ x-linked agammaglobulinaemia
X-linked
No B cells therefore no Ig
T cells function normal
Recurrent bacterial infections, viral and fungal infection normal
Di-Goerge Syndrome
Congenital-damage to 3rd and 4th pharyngeal pouches due to 22q11 (CATCH 22)
- CARDIAC (Aortic arch-heart failure)
- ATRESIA (Oesophageal)
- THYMIC (Hypoplasia)
- CLEFT palate (Dysmorphic facies)
- HYPOCALCAEMIA (parathyroid hypoplasia)
T cell deficiency=Viral and parasitic disease
B cells normal
Severe Combined immunodeficiency
Autosomal or x-linked recessive disease
T cell, B cell and lymphopenia
Death <1 year unless bone marrow transplant
Complement factor deficiency
C2-Autoimmune connective tissue disorder
C3-bacterial infections
C5-8 Recurrent Neisseria infections
Infections usually killed by spleen
Encapsulated organisms:
Strep. pneumoniae
Neisseria Meningitidis
Haemophilus influenzae
Post splenectomy vaccination
HiB vaccine and meningococcus vaccine prior to or after surgery
Pen V or erythromycin life long
Complement and B cell deficiency causes
pyogenic bacteria:
Staphy
Strep
Haemophilus
Neisseria
Phagocyte deficiency
Staph
Gram negative
Fungal
T cells
Opportunistic infections
Kostmann’s syndrome
Congential neutrophilia
Leukocyte adhesion deficiency
No ability for chemotaxis
