Transcript Autoimmune Diseases

Autoimmune Diseases
Henry O. Ogedegbe, PhD., C(ASCP)SC
Department of EHMCS
Learning Objectives
• Upon completion of these materials the student will be able
to:
• Describe contributive factors to autoimmune diseases
• Distinguish organ specific and systemic autoimmune
diseases with examples of each
• Describe the effects of SLE on the body
• List four types of autoantibodies found in lupus and
describe pattern seen in IFA testing
• Discuss the symptoms of rheumatoid arthritis
• Describe the characteristics of the Abs found in rheumatoid
arthritis
Learning Objectives
• Differentiate Hashimoto’s thyroiditis and Graves’ disease
on the basis of lab findings and immune mechanism
• List the main Abs tested for in Graves’ and Hashimoto’s
diseases and describe testing procedures
• Relate genetic susceptibility to the development of insulin
dependent diabetes mellitus
• Explain immunologic mechanism known to cause
destruction of  cells in insulin-dependent diabetes
mellitus
• Discuss immunologic findings in multiple sclerosis,
myasthenia gravis and Goodpasture’s syndrome
Introduction
• Autoimmune diseases are the result of damage to the body
by the presence of autoantibodies or autoreactive cells
• About 2% of the population are affected by such diseases
• There is a breakdown of self tolerance in these individuals
• Self tolerance is brought about by such mechanisms as
clonal deletion of relevant effector cells, active regulation
by TS cells and regulation through idiotypic networks
• Majority of T cells that are processed through the thymus
do not survive. Self reactive T cells are destroyed
• Loss of TS cells may encourage the production of autoAbs
Introduction
• MHC molecules influence Ag recognition or
nonrecognition by determining peptide that can be
presented to T cells
• The expression of class II molecules on host cells may
result in presentation of self Ags for which there is no
tolerance
• In several diseases, there are host cells that exhibit class II
molecules on their surfaces after inflammatory response
• Such cells may function as Ag presenting cells for their
own cellular proteins
Introduction
• Genetic variation in MHC Ag may account for increased
susceptibility in certain individuals
• Idiotypic network may also play a part in autoimmune
diseases
• This refers to situations whereby antibodies are produced
against antibodies
• When an Ab is produced for the first time, the variable
region may be seen as foreign by the host
• The host may then produce antibodies against it
• The anti-idiotypic Ab may have reactivity against self Ags
Introduction
• Anti-idiotypic Abs are found in diseases such as
myasthenia gravis, diabetes mellitus, and Graves’ disease
• The anti-idiotypic Abs may mimic the original Ab and
combine with the receptor for that Ag
• Defects in natural killer cells, in the secretion of ILs, in
phagocytosis and complements may also contribute
• Hormones especially estrogen have been found to enhance
B-cell activation and suppress regulator activities of T cell
• Environmental conditions such as infectious agents like
viruses, bacteria and drugs contribute to autoimmunity
Systemic Lupus Erythematosus
• It is a chronic systemic inflammatory disease marked by
alternating exacerbation and remissions
• Approximately 1 in every 2000 individuals are affected
• Age of onset is usually b/w 20 and 40 yrs of age
• Women are much more likely than men to be stricken by a
margin of 13 to 1
• Etiology is unknown but may be due to genetic and
environmental factors
• In whites, it is strongly associated to with HLA-DR3 or
DR2 and DQB1
Systemic Lupus Erythematosus
• Clinical Signs:
• The first signs to appear are usually nonspecific such as
fatigue, weight loss, malaise, fever, and anorexia
• Joint involvement of small joints of the hands, wrist and
knees is reported in over 90% of cases
• A skin manifestation of an erythematous rash may appear
in the area of body exposed to UV light
• A classic butterfly rash across the nose and cheeks which is
responsible for the name lupus may appear
• Some patients may also exhibit renal involvement
Systemic Lupus Erythematosus
• Renal involvement is usually in the form of lesions the
most dangerous of which is glomerulonephritis
• Immune complexes may deposit in the subendothelial
tissue and thickening of the basement membrane results
• All of these can result in renal failure and death
• There might also be cardiac involvement with pericarditis,
tachycardia, or ventricular enlargement.
• CNS manifestation such as seizures, psychoses, or
depression
• Hematologic abnormalities such as anemia, leukopenia or
lymphopenia are exhibited
Systemic Lupus Erythematosus
• Immunological Findings:
• The LE cell was discovered by Malcolm and Hargraves in
1948.
• The LE cell is a neutrophil that has engulfed the antibodycoated nucleus of another neutrophil
• The first anti-DNA antibody was discovered 9 years later
• SLE is associated with more than 28 autoantibodies
• Lupus patients appear to have overactive B cells especially
the subset with the CD5 marker which increase in number
Systemic Lupus Erythematosus
• The increased prevalence of the disease in women may be
traced to the fact that estrogen enhance B cell activity
• Estrogen also suppresses regulator activities of T cells as a
result, there is a decrease in the absolute number of T cells
• Complement is activated which results in decrease in the
serum level of complement components
• At the same time there is an increase in the level of
breakdown products of complements such as C3d and C3a
• IgG is most pathogenic and it forms complexes that are
deposited in the glomerular basement membrane
Systemic Lupus Erythematosus
• Accumulation of immune complex with complement
activation is responsible for the damage to the kidney
• Drug induced lupus differs from the chronic form of the
disease: when the drug is withdrawn symptoms disappear
• It is a milder form of the disease and manifest as arthritis
or rashes
• Drugs that have been implicated include procainamide
hydrochloride, hydralazine hydrochloride, methyldopa etc.
Systemic Lupus Erythematosus
• Laboratory Diagnosis of SLE:
• A screening test for antinuclear antibody (ANA) is usually
the first test done
• Fluorescent antinuclear antibody (FANA) testing is most
widely used
• The test is sensitive but the specificity is low because
many of the Abs are associated with other diseases
• The test is an indirect IFA test which employs antihuman
globulin tagged with a fluorescent marker.
• About 5% of healthy individuals and b/w 10 and 30% of
elderly individuals test positive
Systemic Lupus Erythematosus
• If FANA is positive, then a profile testing should be done
for individual Abs
• More than 99% of patients with SLE will have a positive
result for one or more tests
Systemic Lupus Erythematosus
• Double-stranded DNA (ds-DNA):
• These Abs are the most specific for SLE and are seen only
in patients with SLE
• Found in only 50 to 80% of cases but when seen, they are
diagnostic of the disease
• Abs to ds-DNA produce a peripheral staining pattern in
IFA
• A sensitive assay for ds-DNA utilizes Crithidia luciliae, a
hemoflagellate as the substrate
• A positive test is indicated by a brightly stained kinetoplast
with a dilution of 1:10 or greater of patient serum
Systemic Lupus Erythematosus
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Antihistone antibody:
Histone is a major component of chromatin
This antibody is found in lupus patients
It binds to DNA and may be found in all cases of drug
induced lupus
• If no other Abs are present, this may support a diagnosis of
drug induced lupus
• The Abs may be detected by IFA, RIA or EIA
Systemic Lupus Erythematosus
• Antibodies are also produced against DNA complexed to
histone known as deoxyribonucleoprotein (DNP)
• The antibody is thought to be identical to the LE factor or
phenomenon
• It appears in 70 to 90% of patients with SLE
• A slide method using latex particle coated with DNP have
been used in a simple slide agglutination test for SLE
• Anti-Sm antibody:
• Antibody to extractable nuclear antigen was first described
in a patient named Smith hence it is called anti-Sm
Systemic Lupus Erythematosus
• Extractable nuclear Ags are small nuclear riboproteins that
are associated with uridine-rich ribonucleic acid (RNA)
• The Ab is specific for SLE and not found in other
autoimmune diseases
• Anti-Sm can be measured by double diffusion, passive
hemagglutination, and EIA
• SS-A/Ro and SS-B/La are also members of the family of
extractable nuclear antigens.
• Antibody to SS-A/Ro appears in 25 to 40% of patients
with SLE
Systemic Lupus Erythematosus
• It is found in patients with cutaneous manifestations of
SLE
• SS-B/La is found in 10 to 15% of patients with SLE and
all of them have anti-SS-A/Ro
• Antibodies are detected by the IFA test with the use of
human tissue culture cells e.g. (Hep-2) human epidermal
• Anti-nRNP:
• Anti-nRNP produces a finely speckled IFA pattern
• RNP is a nuclear RNA which is found in association with
seven to eight nonhistone proteins
Systemic Lupus Erythematosus
• The antibody is also found in high titer in individuals with
mixed connective tissue disease and other autoimmune
diseases
• The antibody can be measured by double diffusion, passive
hemaglutination and EIA and IFA
• Treatment:
• If the primary symptom is fever or arthritis a high dose of
aspirin or other anti-inflammatory drug may bring relief
• May also use antimalarials and topical steroids. Other
drugs include cyclophosphamide, methotrexate etc.
Rheumatoid Arthritis
• Rheumatoid arthritis is a systemic autoimmune disorder
• It involves the synovial membrane of multiple joints
• Women are more likely to be affected than men and
usually strikes between the ages of 20 and 40
• Spontaneous remission may be experienced by some
patients otherwise the disease may progress and result in
deformity and disability
• RA has been associated with certain of the HLA class II
molecules.
• HLA-DR1 and DR4 occur in 70% of patients with RA
Rheumatoid Arthritis
• Clinical Signs:
• Diagnosis of RA is based on the 1987 criteria established
by the American College of Rheumatology
• Symptoms include morning stiffness around the joints
lasting at least 1 hour, swelling of the soft tissue around
three or more joints
• Others include swelling of the proximal interphalangeal,
metacarpophalangeal, or wrist joints, symetric arthritis,
subcutaneous nodules, a positive RF test
• Also included is a radiographic evidence of erosion of the
joints of the hands, the wrist, or both
Rheumatoid Arthritis
• Usually begins with nonspecific symptoms such as fever,
malaise, weight loss, and transient joint pain
• Stiffness and joint pain that gradually improves during the
day are characteristics exhibited by most patients
• Joint are involved progressively to larger joints in a
symmetric manner from the knees, hips, elbows, shoulders
and cervical spine
• About 25% of patients have nodules over the bones
• Nodules may also be found in the myocardium,
pericardium, heart valve, pleural, lungs, spleen, and larynx
Rheumatoid Arthritis
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Immunologic Findings:
The main immunologic finding is the presence of RF
RF is a 19S Ab directed against the Fc portion of IgG
The Ab is not specific for RA as it is found in other
diseases such as SLE, scleroderma, Sjögren’s syndrome
and B cell lymphoproliferative disorders
• It has been suggested that RF may be anti-idiotypic
antibodies involved in the regulation of immune response
• In RA, polyclonal activation of B cells may occur resulting
in overwhelming amount of antibody to IgG
Rheumatoid Arthritis
• Other autoAbs associated with RA include ANA,
anticollagen Abs, Abs against cytoskeleton filamentous
proteins etc.
• These Abs may cause immune complex formation with the
activation of complement which contribute to pathogenesis
• Joint damage is due to invasion of inflammatory cells such
as neutrophils, and macrophages
• Proliferation of fibroblast, macrophages, mast cells, and
stellar cells result in the formation of a pannus, an
organized mass of cells that grow into the joint space
Rheumatoid Arthritis
• Laboratory Diagnosis of Rheumatoid Arthritis:
• Diagnosis is based on a combination of clinical
manifestations, radiographic findings and lab tests
• Laboratory screening test for RF using sheep red cells or
latex particles are available and simple to perform
• Quantitative test are also available which involve
nephelometry and ELISA techniques
• RF is found in other diseases such as syphilis, viral
infections, leprosy, chronic liver disease, neoplasm and
other inflammatory processes
Rheumatoid Arthritis
• The RF test is thus not a specific test for RA and about
10% of patient with the disease test negative for RF
• C-reactive protein and ESR are usually elevated and
complements are normal or elevated
• Treatment:
• Treatment include palliatives with rest and nonsteroidal
anti-inflammatory drugs like salicylates and ibuprofen
• Slow-acting antirheumatic drugs (SAARDS) may also be
used to treat the condition
• New therapy include the use of monoclonal Abs that target
T cells
Hashimoto’s Thyroiditis
• Hashimoto’s thyroiditis and Graves’ disease are organ
specific autoimmune diseases
• Both diseases interfere with the thyroid gland function
• The thyroid gland located in the anterior region of the neck
consist of units called follicles
• Follicles are lined with cuboidal epithelial cells and filled
with colloid
• The primary constituent of colloid is thyroglobulin which
is made up of triiodothyronine (T3) thyroxine (T4)
• TRH acts on the pituitary gland to induce the release of
TSH
Hashimoto’s Thyroiditis
• TSH binds to receptors on the cell membrane of the
thyroid gland causing break down of thyroglobulin into T3
and T4
• AutoAbs may interfere with this process and cause under
or overactivity of the thyroid
• Hashimoto’s thyroditis is most often seen in women
between the ages of 30 and 40 years
• Patients develop a combination of goiter or enlarged
thyroid, hypothyroidism and thyroid autoantibodies
• An association with HLA antigens DR4 and DR5 has been
noted. DQA1 and DQB1 genes seem to confer resistance
Hashimoto’s Thyroiditis
• Immunologic Findings:
• Lymphocytic infiltration is seen with development of
germinal centers that almost replace the normal glandular
architecture of the thyroid
• Cell infiltrates include T and B cells, macrophages and
plasma cells
• Both CD4 and CD8 cells are found thus the disease is
characterized by a cellular and a humoral response
• Autoantibodies are found in up to 80% of cases
Hashimoto’s Thyroiditis
• Laboratory Testing:
• The autoantibodies present include Abs to thyroglobulin
and to thyroid microsomal antigen now known as thyroid
peroxidase
• Some peroxidase Abs inhibit enzyme activity while others
may mediate the cytotoxicity due to natural killer cells
• Abs to thyroglobulin help to produce hypothyroid
conditions
• Other Abs include colloid Ab (CA2) thyrotropin-binding
inhibitory immunoglobulin (TBII)
Hashimoto’s Thyroiditis
• Others are thyroid stimulating immunoglobulin (TSI) and
thyroid growth-stimulating immunoglobulin (TGSI)
• Peroxidase Abs can be measured by particle agglutination
assays, complement fixation, RIA and Indirect IFA
• Abs to thyroglobulin can be measured by precipitaion in
agar, indirect IFA, passive agglutination, RIA, and EIA
• Indirect IFA use human or monkey thyroid tissue fixed to a
slide
• Antithyroglobulin Abs are found in about 80% of patients
with the disease
Graves’ Disease
• Graves’ disease is another autoimmune disease that affects
the thyroid gland
• Graves’ disease produces hyperthyroidism
• It the most common cause of hyperthyroidism and affects
about 0.5% of the population
• Women are more susceptible than men by a margin of 7:1
and usually present between the ages of 30 and 40.
• In whites, the disease is associated with the HLA antigen
DR3 while in Asians HLA Bw35 and Bw36 occur more
frequently
Graves’ Disease
• HLA DQB1 appears to confer resistance to the disease
• Clinical Signs:
• Disease is presented as thyrotoxicosis with a diffusely
enlarged goiter that is soft instead of rubbery
• Signs include nervousness, insomnia, depression, weight
loss, heat intolerance, sweating, rapid heart beat
• Other signs include fatigue, cardiac dysrhythmias,
restlessness, and exopthalmus
Graves’ Disease
• Immunologic Findings:
• The thyroid presents with Hyperplasia with a patchy
infiltration of lymphocytes
• Both CD4 and CD8 cells are present and the T cells appear
to play a central role in the pathogenesis of the disease
• The most significant Ab present is thyroid stimulating
hormone receptor antibody (TRab)
• Ag-Ab combination result in the stimulation of the
receptor resulting in the release of the thyroid hormones
• Another group of Abs called thyroid stimulating antibodies
or immunoglobulins (TSab or TSI) may have different
specificity
Graves’ Disease
• Laboratory Diagnosis:
• A key finding in Graves’ disease is elevated levels of total
and free T3 and T4
• In addition, TSH levels are low due to Ab stimulation of
the thyroid
• Measurement of the thyroid Abs may be undertaken if the
above assays are unclear
• Treatment:
• Antithyroid medication may be employed. Radioiodine
which emits beta particles may be used. Surgery is also an
option.
Insulin-Dependent Diabetes
• This disease is characterized by insufficient production of
insulin due to an autoimmune destruction of the beta cells
of the pancreas
• Peak onset is b/w 10 and 14 years of age
• Disease may be attributed to genetic and environmental
conditions
• About 95% of white diabetics carry the HLA-DR3 or DR4
genes
• It appears that true susceptibility genes for IDDM may
occur in the HLA-DQ region
Insulin-Dependent Diabetes
• Viral infections have been linked with diabetes
• Mumps virus, rubella virus, CMV, and Coxsakie B4 virus
have all been inconclusively linked to diabetes
• Congenital rubella infection is the only one for which a
link has been definitively identified
• There appears to be similarity between coxsakie viral
protein P2-C and the enzyme glutamic acid decarboxylase.
• Antibodies are formed against glutamic acid decarboxylase
in IDDM
• Molecular mimicry could initiate Ab production against
self Ag
Insulin-Dependent Diabetes
• Immunopathology:
• Inflammation of the islets of Langerhans in the pancreas
leads to fibrosis and destruction of most of the beta cells
• CD4 and CD8 B cells and macrophages are all involved in
the destructive process of the islet cells
• Cellular and humoral immunity are involved in this
process
• The subset of T cells that is activated determines whether
the response is cellular or humoral
Insulin-Dependent Diabetes
• Laboratory Testing:
• IDDM is usually diagnosed by the presence of
hyperglycemia
• Abs to islet cells may be screened for by indirect IFA with
human or rat islet cells
• Islet cell may be detected in the sera of newly diagnosed
diabetic cases
• Abs to insulin may be detected by ELISA or RIA methods
Insulin-Dependent Diabetes
• Treatment:
• Insulin has been the standard form of treatment
• New treatment methods center around the use of
immunosuppressive agents
• Agents that have been tried include azathioprine,
cyclosporine A and prednisone
• All these agents have potentially toxic effects
Multiple Sclerosis
• Destruction of the myelin sheath results in the formation of
lesions known as plaques in the white matter of the brain
and spinal cord
• Genetic and environmental factors predispose one to this
disease
• MS is associated with the inheritance of HLA antigen
DRw15 and DRw6
• An inflammatory response to bacteria or virus may trigger
the autoimmune process
• Disease is most often seen in those b/w the ages of 20 &
50 and is more common in women
Multiple Sclerosis
• 90% of patients alternate between remissions and relapses
for many years
• Within the plaques, CD4 cells, plasma cells and
macrophages are found along with immunoglobulin
• Immunoglobulin is increased in the spinal fluid in 60 to
80% of patients
• They usually produce oligoclonal bands on protein
electrophoresis
• RIA is used to detect the Abs
• Therapy include use of corticosteroids
Myasthenia Gravis
• Symptoms of disease include facial weakness, difficulty in
chewing, and swallowing, difficulty breathing
• Others include inability to maintain support of the trunk,
the neck or the head
• Antibody mediated damage to the acetylcholine receptors
in the skeletal muscle leads to muscle weakness
• May be associated with the presence of other autoimmune
diseases such as SLE
• Appears to be linked with either HLA-B8 or DRw3
antigens
Myasthenia Gravis
• 80 to 90% of patients have Abs to acetylcholine receptors
which may be the main contributor to pathogenesis
• Combination of the Abs to the receptors blocks the binding
of acetylcholine which destroy the receptors
• Abs can be detected with RIA methods
• Anticholinesterase agents are employed in therapy
Goodpasture’s Syndrome
• Goodpasture’s syndrome is a glomerulonephritis due to
Abs reacting specifically with Ags in the kidney
• Necrosis of the glomerulus is triggered by an Ab that reacts
with glycoprotein present in the basement membrane of the
glomerulus
• Results in immune complex deposit and complement
fixation which causes the damage to the kidney
• This may eventually produce renal failure