Immunology Chapter 16 — Disruption of healthy tissue by the
adaptive immune response
Autoimmune diseases – immune response against “self”
More than 100 different types
More common in industrialized countries
Higher incidence in females than males
Chronic disease – you cannot be cured
Failure to achieve tolerance (inhibition) for self. What causes these failures?
This is not exactly known. One of the hypotheses is the hygiene hypothesis:
countries low incidence of infectious diseases due to high hygiene have high
incidence of autoimmune diseases
Often runs in the families – genetic predisposition is mainly mediated by HLA
molecules. For certain autoimmune diseases there is a correlation with MHCI
allotypes but the correlation with MHCII allotypes is much stronger.
So, this suggest that there is a relationship between T helper cell activation
and autoimmune diseases
Mechanism to achieve tolerance (inhibition) for self
Central tolerance: induced in primary lymphoid organs
o Thymus – T cells
Apoptosis
Regulatory T cells are induced: suppress the CD4+ T cells
o Bone marrow – B cells
Receptor editing
Apoptosis
Anergy
Peripheral tolerance
o Apoptosis
o Anergy
o Regulatory T cells: suppress the CD4+ T cells
Different types of autoimmune disease
Antibody mediated
1. Antibodies directed against cell surface or matrix antigens (type II)
a. Autoimmune haemolytic anemia
Patients make antibodies against red blood cells --> antibodies bind to
red blood cells --> complement is activated and there is direct lysis of
red blood cells + red blood cells are being cleared because they bind to
FcR expressed on macrophages in the spleen this led to phagocytosis
Consequence: destruction of red blood cells by complement and
phagocytosis which lead to anemia (lack of healthy red blood cells)
Symptoms: fatigue, weakness, irregular heartbeats, shortness of
breath, dizziness
Cause: unknown but it can be drug induced by penicillin. Penicillin can
bind to surface of red blood cells and acts as an antigen and this raises
the antibodies
adaptive immune response
Autoimmune diseases – immune response against “self”
More than 100 different types
More common in industrialized countries
Higher incidence in females than males
Chronic disease – you cannot be cured
Failure to achieve tolerance (inhibition) for self. What causes these failures?
This is not exactly known. One of the hypotheses is the hygiene hypothesis:
countries low incidence of infectious diseases due to high hygiene have high
incidence of autoimmune diseases
Often runs in the families – genetic predisposition is mainly mediated by HLA
molecules. For certain autoimmune diseases there is a correlation with MHCI
allotypes but the correlation with MHCII allotypes is much stronger.
So, this suggest that there is a relationship between T helper cell activation
and autoimmune diseases
Mechanism to achieve tolerance (inhibition) for self
Central tolerance: induced in primary lymphoid organs
o Thymus – T cells
Apoptosis
Regulatory T cells are induced: suppress the CD4+ T cells
o Bone marrow – B cells
Receptor editing
Apoptosis
Anergy
Peripheral tolerance
o Apoptosis
o Anergy
o Regulatory T cells: suppress the CD4+ T cells
Different types of autoimmune disease
Antibody mediated
1. Antibodies directed against cell surface or matrix antigens (type II)
a. Autoimmune haemolytic anemia
Patients make antibodies against red blood cells --> antibodies bind to
red blood cells --> complement is activated and there is direct lysis of
red blood cells + red blood cells are being cleared because they bind to
FcR expressed on macrophages in the spleen this led to phagocytosis
Consequence: destruction of red blood cells by complement and
phagocytosis which lead to anemia (lack of healthy red blood cells)
Symptoms: fatigue, weakness, irregular heartbeats, shortness of
breath, dizziness
Cause: unknown but it can be drug induced by penicillin. Penicillin can
bind to surface of red blood cells and acts as an antigen and this raises
the antibodies
