W5 auto immune and collagen diseases Flashcards
what is autoimmune disease and collagen vascular disease?
-Autoimmune disease refers to diseases that result from an abnormal inflammatory (immune)
response to self-antigens.
-Collagen-vascular diseases are diseases that result from chronic
inflammation in connective tissues, most of which have an underlying autoimmune aetiology
Explain why an understanding of autoimmune and collagen-vascular disease is important
for clinical practice.
- clinical presentation
- appropriate tests to diagnose these conditions
- treatment modalities
what is the function of the immune response?
to protect the body from injurious stimuli, specifically infectious micro organism
Briefly describe the components of a normal human immune response
- Innate immunity
-adative immunity: cell-mediated immunity
humoral immunity
what is innate immunity?
initial reponse to injurious stimuli.
comprised of epithelial barrier, cell type(macropahges, neutrophils, dendritic cell, NK, mast cell) & soluble protein (complement cascade)
what is the adaptive immunity?
-Facilitated by lymphocytes (T-cells and B-cells) – recognition of one specific antigen via unique
receptor on individual cell.
-T-cells express T-cell receptors – recognise fragments of antigens on MHC molecules (on surface of
antigen presenting cells) = 2.1. Cellular immunity.
-B-cells recognise antigens via membrane-bound antibodies subsequently they are activated to
become plasma cells and produce antibodies = 2.2. Humoral immunity.
what is abnormal immune response?
Immune responses that are injurious to the body are called hypersensitivity reactions. These result
from an excessive immune response with an imbalance in effector and regulatory mechanisms.
what are the hypersenstivity reaction types?
I immediate: IgE
II antibody mediated: IgG and IgM
III immune complex mediated: antigen- antibody complex
IV cell medaited: activation of Lymphocytes
what hypersensitive reactions are not autoimmune?
anaphylaxis
asthma
allergies
what is self tolerance?
refers to the immune system’s ability to not react to the individual’s normal occurring antigens
*The abnormal immune response in autoimmune disease results primarily from a breakdown in self-
tolerance i.e. the immune system develops the ability to react to self-antigens
central torelence
Results in the deletion or inactivation of B-cells or T-cells that show high affinity for self-antigens:
a. T-cells: in thymus, developing T-cells are exposed to self-antigens – if their T-cell
receptors have a high affinity for self-antigens, they are deleted, while some are
inactivated and remain regulatory T helper cells (autoimmune regulator – AIRE –
prominently involved).
b. B-cells: developing B-cells that show strong affinity for self-antigens re-activate their
immunoglobulin rearrangement mechanisms and alter their B-cell receptor
composition.
This is not a perfect process, and some self-reactive B-cells and T-cells escape to the periphery, thus
a second system is in place to further reduce the risk of loss of self-tolerance
how does the peripheral tolerance evade central mechanisms of B and T cells?
- Anergy: permanent functional inactivation
suppression by regulatory t cells
deletion by apoptosis
antigen sequestration
how does the combination of genetic factors and environmental trigger function?
a. Loss of self-tolerance and / or defective regulation of immune responses.
b. Abnormal display of self-antigens (altered antigens due to stress or injury).
c. Inflammation-driven lymphocyte activation
what are the general features of autoimmune diseases?
-Progressive
* Epitope spreading
* Disease characteristics dependent on type of hypersensitivity reaction
* Overlap between different autoimmune diseases
what antibodies are found in SLE?
antinuclear antibodies
*Anti-double-stranded DNA and anti-Smith antigen antibodies
