1. Diseases of the autoimmune
system
Dr. Fardan Qadeer
Dept. Of Pathology
CIMS and H, Lucknow
2. SLE
Systemic Lupus Erythematosus
It is an autoimmune disorder which involves
multiple systems of the body
Incidence: it is a fairly common disease and the
prevalence is as high as 1 in 2500
Gender: It has a strong female predisposition,
female is to male ratio is as high as 9:1
Age: it can occur at any age group but usually
common in 2nd to 3rd decade of life
3. Etiology: The exact etiology of the disease is
unknown but various factors are attributed to
the development of autoimmunity
• Genetic factors:
▫ A high rate of concordance in monozygotic twins
(25%)
▫ Positive association of disease with class 2 HLA
gene particularly HLA-DQ
4. • Environmental factors:
▫ Ultraviolet radiation (sun exposure) exacerbates
the lesion
▫ Drugs: certain drugs like procainamide and
hydralazine may lead to development of SLE like
features
▫ Role of estrogens can be attributed to the higher
incidance of disease in females
5.
6. The fundamental defect in SLE is failure to
maintain self-tolerance
• As a result of this a large number of auto
antibodies are produced which cause tissue
destruction by two mechanism
▫ Type 2 hypersensitivity: characterised by
formation of antibodies against blood components
and resulting in haematological derangement
▫ Type 3 hypersensitivity: immune complex get
deposited in different tissues resulting in systemic
resposes
7. Pathology: The disease is characterised by formation of
various antibodies
• Antinuclear antibodies(ANA): these are antibodies
against common nuclear antigen that include both DNA
and RNA
• Antibodies to Double stranded DNA (anti-dsDNA) and
single stranded DNA (anti-ssDNA) are most specific
• Antibodies to smith antigen(anti-SmAg) are also formed
which is a part of ribonuleoprotein
• Anti ribonuleoproteins(anti-RNP) antibodies
• Anti histone antibodies
• Anti nucleolor antibodies
• Anti phospholipid antibodies
8. • Renal lesions: kidney involvement is one of the
most important feature of SLE
▫ It commonly involves the glomeruli however
tubules and interstitium may be affected
▫ It is due to depostion of immune complexes in the
kidney and subsequent destruction
10. • Small Blood vessels: Small arteries and
arterioles are involved. It is characterised by
necrosis and immune complex deposition
11. • Skin: There is liquifactive
degeneration of the basal layer of
the epidermis and deposition of
immune complexes at the dermo
epidermal junction
• Cardiac lesions (Libman Sacks
endocarditis) characterised by
presence of vegitations on the
mitral and tricuspid valves. It can
also cause pericarditis.
12. • CNS: involvement due to formation of thrombus
in the vessel walls caused by ANA deposits. It
leads to microinfarcts and subsiquent
neurological deficit.
13. Clinical Features
• Malar rash:
Characterised by erythematous and maculopapular
eruptions over the malar eminance and bridge of the nose
• Discoid rash
• Photosensitivity
• Pain less oral or oropharyngeal ulcers
• Arthritis
• Serositis: Pluritis and Pericarditis
• Renal disorders: Renal failure in advanced disease is
the most important cause of death
Persistant proteinuria >0.5 gm/dl
Presence of cellular cast
16. Laboratory Diagnosis
• LE cells: It was the first
diagnostic test for SLE. It is
based on the principal that the
ANAs cannot penetrate the
intact cells hence the cell
nucleus is exposed to bind the
ANA resulting in formation of a
homogenous mass called as LE
body
• This mass is further engulfed
by phagocytic leucocytes
(polymorphs and monocytes)
to form a LE cell
• This is positive in 70% cases of
SLE only
17. • Antibody titre: It is more reliable than LE cells
immunofluorescence test is positive in almost
100% cases
▫ Anti DNA antibodies
▫ Anti Smith antibodies
▫ Ant nucleolar antibodies
• Supportive evidances
▫ Proteinuria
▫ MRI brain showing microinfarct
▫ Evidance of Pleural effusion on X Ray
▫ Evidance of valvular lesions on 2D Echo
