Biology of Disease

AUTOIMMUNE DISORDERS

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Many, but not all, autoimmune disorders, affect a preponderance of female
patients, with three times as many females as males presenting with
autoimmune diseases. The reasons for this gender bias are unclear but may be
related to sex hormone levels. Many autoimmune disorders show a link with
the type of MHC antigens that are present on cells. In humans, the MHC is
known as the HLA system. The links between HLA type and different diseases
is described in Chapter 6. So, for example, patients with Goodpasture’s
syndrome have a higher incidence of HLA-DR2 than the healthy population.

Autoimmune Disorders Affecting Endocrine Glands

Autoimmune disorders of the thyroid gland are among the most common
autoimmune disorders. Some will be discussed in Chapter 7. Autoimmune
thyroiditis, also known as Hashimoto’s thyroiditis, results in hypothyroidism
and myxedema. The disease presents, typically, in women of middle age
who are overweight, lethargic, constantly feel cold, are constipated and have
coarse, dry hair and skin. The thyroid is swollen with a generally painless
goiter, but which has a rubbery consistency when palpated. A biopsy of
the thyroid shows infiltration with both CD8+ and CD4+ T lymphocytes
that progressively destroy the thyroid gland. Patients also have antibodies
to thyroglobulin and to thyroid peroxidase, which can be determined by

Type of disorder Example Effect of disorder Autoantibodies present Autoreactive T cells

Organ specific autoimmune

hemolytic anemia

destruction of erythrocytes

(Chapter 13)

antibodies to erythrocyte

antigens

autoimmune thyroiditis hypothyroidism

(Chapter 7)

antibodies to thyroglobulin and

thyroid peroxidase

TH1 cells specific for thyroid

antigens

Addison’s disease adrenal insufficiency

(Chapter 7)

antibodies to cytoplasmic antigens

of cells of adrenal cortex

infiltration of adrenal cortex with

autoreactive T cells

type 1 diabetes mellitus destruction of insulin-producing

cells in pancreas; serious

metabolic disturbances

antibodies to islet cells found in

classical juvenile form

infiltration of pancreas with

autoreactive T cells

Goodpasture’s syndrome progressive kidney and lung

damage

antibodies to basement membrane

antigens of kidney and lung

Graves disease hyperthyroidism

(Chapter 7)

antibodies to thyroid stimulating

hormone receptors

destruction of thyroid cells by

autoreactive T lymphocytes

myasthenia gravis progressive muscle weakness antibodies to acetyl choline

receptors on muscle cells

pernicious anemia failure to absorb vitamin B 12

in the stomach

(Chapters 11and 13 )

antibodies to intrinsic factor

Systemic disease rheumatoid arthritis (RA) inflammatory disorder affecting

joints, skin and internal organs

antibodies to IgG (rheumatoid

factor)

infiltration of joints with

autoreactive T lymphocytes

systemic lupus

erythematosus (SLE)

inflammatory disorder affecting

multiple organ systems

antibodies to DNA, chromatin

and histones;

rheumatoid factor in some

individuals

evidence of T cell reactivity in

some of the many organs affected

multiple sclerosis (MS) inflammatory disorder

affecting central nervous system

antibodies to myelin basic protein destruction of myelin membrane

by autoreactive T lymphocytes

Table 5.7Some examples of autoimmune disease