5- Disorders of the immune system Flashcards
Antimicrobial resistance can cause
death in approx. 700,000 people.
What are the defences against infection
NSATI
Non- specific mechanisms
Specific immunity
Antigens
T lymphocytes and plasma cells
Immune response- humoral and cellular
What is the non specific mechanism
This is also known as innate mechanisms (They lack memory)
- Mechanical barriers (skin barrier, ciliary motion in the respiratory tract): failure results in infection e.g. defects in mucociliary lining in cystic fibrosis (Conjunctiva – has mast and dendritic cells)
- Secretory factors act as chemical barriers (lysozyme in secretions) e.g. absence of gastric acid in atrophic gastritis causes overgrowth of gut bacteria (Tear film – contains enzymes and other proteins)
- Cellular factors include phagocytes and macrophages (Type of leukocytes): ingest & kill bacteria (Cornea – avascular)
- Complement: complex series of interacting plasma proteins. Can destroy pathogens directly or mark them for destruction by immune cells.
What is specific immunity
other mechanisms are ……… its also known as ………
is only used when other mechanisms are bypassed (B cells and T cells). Also known as Adaptive immunity
What are the four essential features of specific/ adaptive immunity
sdmr
SDMR
- Specificity - consists of a specific response to an antigen and a non-specific augmentation of the effect.
- Diversity - ability to recognize and respond to all pathogens
- Memory - second time around a quicker and larger response
- Recruitment - of other defence mechanisms e.g. innate mechanisms such as complement and macrophage activation
What are antigens (epitopes)
provoke an ………….. and react with……… or ………..
They provoke an immune response and react with immune products or cells
An antigen may have many antigenic sites (epitopes)
- Each epitope can stimulate a different immune reaction
The immune system can produce humoral (antibody) or cellular (Lysis – breakdown of plasma membrane of cells) immune reactions to antigens
What are T lymphocytes and plasma cells
originate in…….
They originate in the bone marrow
T cell membrane receptor - Recognises APC (Antigen-Presenting cell) as part of a complex of antigenic peptide and Major Histamine Compatibility (MHC) Complex
Helper T cells coordinate the cellular immune reaction by activating and directing other immune cells
T lymphocyte Cytotoxic - release cytokines triggering inflammation (Directly kill infected cells)
What are B lymphocytes
differentiate into………. that produces ………… and binds to …
differentiate into plasma cells that produce immunoglobulin (Antibody molecule) that binds to antigen.
Immune response- humeral and cellular
component, function, action and target for each
Humoral Immune Response:
Main Players: Involves B cells, a type of white blood cell.
Function: B cells produce antibodies (immunoglobulins) that circulate in the blood and lymph.
Action: Antibodies bind to antigens, neutralizing them or marking them for destruction.
Targets: Effective against extracellular pathogens like bacteria, viruses outside cells, and toxins.
Cellular Immune Response:
Main Players: Involves T cells, another type of white blood cell.
Function: T cells directly attack infected or abnormal cells in the body.
Additional Roles: T cells can activate other immune cells and regulate the immune response.
Targets: Effective against intracellular pathogens like viruses infecting host cells and cancer cells.
When does complement activation occur
when……. …………. ……………. triggers it
when antibodies, bacteria, or mannose binding lectin triggers it. It removes and destroys antigens through direct lysis
What is immunodeficiency
Underlying immunodeficiency should be suspected in any patient who has recurrent, persistent, severe or unusual infections, irrespective of age.
What are the types of immunodeficiency and examples
Primary
- Acquired – Caused by infections, medications or underlying health conditions.
HIV / Chemotherapy induced immunosuppression.
- Congenital – Caused by genetic mutations or defects
-Severe combined immunodeficiency (Affects B cells and T cells)
-X-Linked agammaglobulinemia (Affects B cells and immunoglobulins)
Primary immunodeficiency disorders are inherited conditions that impair the immune system’s ability to effectively fight infections and diseases.
Secondary immunodeficiency disorders are acquired conditions that weaken the immune system’s ability to protect the body.
What are the effects of immunodeficiency
immunodeficiency can leave them vulnerable to infections and more severe symptoms. They can be also vulnerable to certain cancers
What is secondary immunodeficiency
More common than primary forms
What are opportunistic infections
These are infections that occur in those with weakened immune systems and can be caused by a wide range of microorganisms.
Examples of opportunistic infections
- Candida
- Staphylococci
- Bacteria or Fungi
- Herpes
What are hypersensitivity reactions
Damaging immunological reactions
What are the types of hypersensitivity reactions
- Type I: immediate hypersensitivity “allergy” due to ↑ IgE (Type of antibody for allergies) on mast cells (Systemic anaphylaxis, Asthma)
- Type II: antibody against cell-bound antigen (B cells bind to the cell-bound antigen and activate the complement system.)(Graves disease)
- Type III: Result from the deposition and formation of immune complexes in tissue = Tissue damage and inflammation (Vasculitis)
- Type IV: delayed sensitivity mediated by T cells (corneal graft/other transplant rejection)
- Sensitised T cells react with antigen and secrete cytokines
-Cytokines attract and activate more T cells, macrophages form granulomas
What is auto immune disease
Immune system reacts against “self” antigens. It is usually specifically unreactive (tolerant) to these antigens
- Disease may be restricted to one organ (organ-specific autoimmune disease) e.g. myaesthenia gravis, autoimmune thyroiditis.
- or involve antigens distributed throughout the body (non-organ specific autoimmune disease) e.g. rheumatoid disease, systemic lupus erythematosus
Who are auto immune diseases more common in
They are more common in women than in men
Immunity in the eye
what barrier
its function
ocular space is…… …………..
Blood retinal barrier – Specialised barrier that prevents immunes cells from entering the retina
Very similar to the blood brain barrier as both are neural derived tissues
The ocular space is said to be immune privileged. (Tolerate presence of foreign substance)
What are the consequences of the immune privilege
-Risk of autoimmune reactions
-Offers “safe harbour” and chemo-resistance to infectious organisms that breach the barrier
-Delayed detection of cancers
-Intervention breaches privilege
