Theme 2 Lecture 7: Autoimmune diseases Flashcards
What is innate immunity and what cells does it involve?
- inflammation in target tissues
- pattern recognition against broad classes of antigen
- fast response but short lasting
- involves macrophage, dendritic cells, mast cells, neutrophils and complement
What is adaptive immunity and what cells does it involve?
- learned responses in immune organs
- highly specific
- slow response but long lasting
- T and B cells
Is there memory, amplification or regulation involved in innate immunity?
no memory, no amplification, little regulation
Is there any memory, amplification or regulation involved in adaptive immunity?
strong memory, amplification component, many regulatory mechanisms
How do the innate and adaptive immune systems interact?
- innate immune cells directly detect and attack antigenic targets - occurs at sites of infection, phagocytosis, cytotoxicity, inflammatory mediators and chemokines to attract other cells
- dendritic cells present antigen to T cells
- Cross talk between DCs, T cells and B cells
- immune memory to determine specific learned responses
- occurs in lymphoid tissues - adaptive immune cells activate innate immune cells, directing tissue inflammation to specific targets
- T cell cytokines activate monocytes, macrophages
- B cell antibodies activate complement
What are 3 types of phagocytic cells and what do they do?
- Neutrophils: eat and destroy pathogens
- Macrophages: eat and destroy pathogens and also produce chemokines to attract other immune cells
- Dendritic cells: eat and destroy pathogens and also present antigen to adaptive immune system
Name the histamine producing cells and their action
- mast cells, basophils and eosinophils:
- produce histamine, other chemokines and cytokines
- vasodilatations - attract other immune cells
- defence against parasites
- wound healing
- allergy and anaphylaxis
What do complement do?
- directly attacks pathogens via alternative and lectin pathways
- may be activated by adaptive immune system via antibodies
What do cytokines do?
send signals between different immune cells
What do chemokines do?
Attract other immune cells to sites of inflammation
What are the two main actions of Th cells?
- could turn into a Th1 cell which produces inflammatory cytokines
- could turn into a Th2 cell which cross-talks with a B cell to produce plasma and memory cells
What is autoimmunity?
the adaptive immune system recognises and targets the body’s own molecules, cells and tissues (instead of infectious agents and malignant cells)
Describe the main characteristics of autoimmunity
- T cells that recognise self antigens
- B cells and plasma cells that make autoantibodies
- inflammation in target cells, tissues and organs is secondary to action of T cells, B cells and autoantibodies
What are the 4 main autoinflammatory conditions?
FMF, TRAPS, CAPS and HIDS
What are the main characteristics of autoinflammation?
- seemingly spontaneous attacks on systemic inflammation
- no demonstrable source of infection as precipitating cause
- absence of high titre autoantibodies and antigen specific autoreactive T cells
- no evidence of auto-antigenic exposure
Compare autoinflammation and autoimmunity in terms of the following:
- Immune system involved
- Main cellular involvement
- Antibody involvement
- Clinical features
- Therapy
- autoinflammation - innate
autoimmunity - adaptive - autoinflammation - neutrophils, macrophages
autoimmunity - B and T cells - autoinflammation - few or no antibodies
autoimmunity - autoantibodies present - autoinflammation - recurrent, often seemingly unprovoked attacks
autoimmunity - continuous progression - autoinflammation - anti-cytokine (IL-1, TNF, IL-6)
autoimmunity - anti-B and T cell
What are some examples of autoinflammatory conditions?
monogenic hereditary periodic fevers, polygenic chrohn’s disease, spondylarthropathies
What is autoimmunity?
breakdown of self tolerance
What are the 3 mechanisms of autoimmunity?
- Failure of central tolerance (T cell selection in thymus and B cell selection in bone marrow)
- Genetic predisposition
- central HLA (MHC) types select for certain self-antigens
- other genes that regulate immune functions - antigenic factors/ environment
What are examples of antigenic factors that can cause autoimmunity?
- infections that trigger autoimmune responses
- environmental triggers: UV light, smoking
- alterations in self proteins that increase their immunogenicity
Explain central tolerance in the thymus
as T cells are randomly generated in the thymus they are tested against self antigens
What genes are MHC Class I molecules encoded by?
HLA-A, HLA-B, HLA-C
Where are MHC Class I molecules found and where do they present ?
- on all nucleated cells
- present antigen to CD8+ T cells
What genes are MHC Class II encoded by?
HLA-DP, HLA-DQ, HLA-DR
