Systemic lupus erythematosus is the classical
non organ specific autoimmune disease.
Like the vast majority of autoimmune diseases,
there are numerous susceptibility genes
involved that lead to the failure of
immunological tolerance against self antigens.
There are a number of
For example, UV radiation can cause apoptotic
cell death of cells and tissues in the individual.
These apoptotic cells are not cleared properly
and there is the development of autoantibodies.
Typical of SLE are
anti-nuclear antibodies or ANA.
And there is the development of anti-double
stranded DNA, anti-histone, anti-Ro,
anti-La, anti-Smith (Sm), anti-ribonucleoprotein
and anti-phospholipid antibodies.
For example, the lupus
anticoagulant and anti-cardiolipin.
These immune complexes of autoantibody and self antigen can
be endocytosed by B-cells and the antigens act as DAMPS
(Damage Associated Molecular Patterns) that are recognized by
endosomal Pattern Recognition Receptors within the B-cells.
Dendritic cells also become activated, and the
activated dendritic cells secrete the type I
interferons - interferon-α and interferon-β, which
can help in the activation of the B-lymphocyte.
So ultimately there is activation of lymphocytes and of
dendritic cells, and the further production of autoantibodies.
There’s a persistent high level
anti-nuclear IgG antibody production.
The clinical features of SLE are many because
of its nature being a systemic disease.
Immune complexes get trapped in locations in
the body where there is very little space.
For example, the glomeruli of the kidney
and the small blood vessels in the skin.
This can lead to renal failure, serosal inflammation
affecting the pleura and pericardium and vasculitis.
Thrombotic disease also occurs due to
the anti-cardiolipin autoantibodies.
And there is impaired hematopoiesis with the development of
antiplatelet autoantibodies and antilymphocyte autoantibodies.
And finally, immune complexes
get deposited within the CNS.
There are antineuronal autoantibodies leading
to neurological and psychiatric morbidity.
Here you can see the classic butterfly rash that
is seen on the cheeks of an individual with SLE.
This is due to damage to the small
blood vessels in the skin of the cheeks.