Unit 3 Autoimmunity
Part 1 Introduction
Terry Kotrla, MS, MT(ASCP)BB
Tolerance
 Do not mount immune response to “self ” antigens.
 Term “self-tolerance”.
 Immune system constantly challenged to discriminate
between self and non-self and make the right choice.
 Under normal circumstances immune system will not
destroy self antigens.
Autoimmunity
 Autoimmunity can be defined as breakdown of
mechanisms responsible for self tolerance and
induction of an immune response against
components of the self.
 Autoimmune disease occurs when the immune
system attacks self-molecules as a result of a
breakdown of immunologic tolerance to
autoreactive immune cells.
Autoimmunity
Autoimmune Response
 Antibody directed against “self ”, termed auto-
antibody
 Considered abnormal but usually does not result
in disease.
 May occur in healthy individuals.
Autoimmune Disease
 Disorder in which tissue injury is caused by an
immunologic reaction of the host to its own
tissues.
 Precise mechanisms unknown.
 Comprising multiple disorders and symptoms
ranging from organ-specific to systemic.
Proposed Mechanisms
 Many mechanisms postulated.
 The following will be discussed:
 Forbidden clone
 Altered antigen
 Sequestered Antigen
 Immunologic deficiency theory
 Genetic influence
Forbidden clone
 Clone of changed or altered lymphocytes arise
through mutation.
 Lack foreign surface antigens, not destroyed.
 Because of alteration may recognize host as
foreign.
 May be cause of increased incidence of
autoimmune disease in elderly.
Altered Antigen
 Surface antigens on host altered by chemical,
biological or physical means.
 This new antigenic determinant may be
recognized as foreign by the host.
Sequestered Antigen
 Some antigens in the body are hidden from cells
of the immune system.
 If there is damage to these organs causing
exposure of these sequestered antigens an
immune reaction to these antigens may occur.
Immunologic Deficiency Theory
 Relates the increased frequency of auto-
antibodies and increased immune system
deficiency to age.
 Mutation or loss of immune regulatory powers
results in the condition in which self antigens
behave as foreign antigens.
Genetic Influence
 It is well recognized that certain immune
disorders predominate in females and in
families.
 Determined by family studies.
 Genetic links have occurred between diseases
and HLA antigens
Contributing Factors
 Defects in the immune system.
 Influence of hormones
 Environmental conditions
Classification of Autoimmune Diseases
 Systemic- the auto-immunity is directed against an
antigen that is present at many different sites and can
include involvement of several organs
 Organ specific - Organ specific means the autoimmunity is directed against a component of one
particular type of organ.
 Both – can get overlap
 Excellent chart on classification:
http://tinyurl.com/3a7oas3
Diagnosis
 Symptoms
 Detection of antibodies reactive against antigen of tissues and
cells involved.
 Tests may involve
 Immunofluorescence
 ELISA
 RIA
 Agglutination
The End