(FE) Week 8 Intro to Immunology Flashcards
Self vs non-self?
Self:
- Particles made by body
- Should not be targeted by the immune system
~ Non-reactivity known as tolerance
Non-self:
- Particles/foreign bodies not made by body
- Potentially harmful
- Makes proteins known as antigens
What are antigens?
- Any molecule that triggers an immune response
- Can be entire pathogens or smaller proteins expressed by them
What are the phases in immunity?
1) Recognition
- Pathogens and host breakdown products
2) Activation
- Inflammation and recruitment of immune cells
3) Effector
- Removal of infectious agent
What are the pros and cons of the immune system?
Pros:
1) Defence against pathogens and cancer
2) Vaccines
Cons:
1) Inappropriate reaction against allergens or self
2) Reaction against transplant tissue
What are the classifications of immune cells?
1) Phagocytes
- Part of innate immunity
- Recognizes and ingests microbes
- Neutrophils, Monocytes, Macrophages, Dendritic Cells
2) Lymphocytes
- Part of adaptive immunity
- Recognizes antigens before differentiating into cells with defense functions
- T, B lymphocytes
3) Antigen-presenting cells
- Captures antigens and displays them to lymphocytes
- Dendritic cells, Macrophages, B lymphocytes
4) Effector cells
- WBC that eliminate microbes
- Lymphocytes, NK Cells
What are the characteristics and MOA of Neutrophils?
- Granulocyte
- Polymorphonuclear
- Innate immune cell
- Against bacteria and fungi
- Ingests microbes, then discharges granules containing microbicidal substances
What are the characteristics and MOA of Basophils?
- Granulocyte
- Circulates the body
- Activated in allergic responses
- Releases active mediators from granules
What are the characteristics and MOA of Eosinophils?
- Granulocyte
- Bilobed nucleus (owl eyes)
- Against helminth infx
- Pathological in asthma
- Releases active mediators from granules
What are the characteristics and MOA of Mast cells?
- Granulocyte
- Innate immune cell
- Activated in allergies, helminth infx and inflammation
- Releases factors from granules
~ eg histamine and lipids
What are the characteristics and MOA of NK cells?
- Large granular lymphocyte
- Innate immune cell
- Early protection against viruses and tumor cells
What are the characteristics and MOA of Monocytes and Macrophages?
- Innate immune cells
- APC
- Monocytes found in blood circulation
~ Can develop into macrophages and dendritic cells when they migrate to tissues - Kills or destroys ingested pathogens
What are the characteristics and MOA of dendritic cells?
- Innate immune cells
- APC
- Found in most tissues
- Captures material in the tissues and processes the material to induce immune response
What are the cells that target viruses, extracellular and intracellular bacteria, and helminths?
Viruses:
- T cells, Antibodies, NK cells
Intracellular bacteria:
- Macrophages, T cells
Extracellular bacteria:
- Neutrophils, Macrophages, Antibodies
Helminths:
- Antibodies, Eosinophils, Mast cells
Where does haematopoiesis occur?
Primary lymphoid organs:
- Fetal liver first
- Bone marrow
- Thymus (for lymphocytes)
What are the 3 major stages of haematopoeisis?
1) Hematopoietic stem cells
- Self- renewing
- Pluripotent
~ Gives rise to all blood cell types
2) Progenitor cells
- Lymphoid or myeloid progenitor cells
~ (L) -> Dendritic cells, NK cells, lymphocytes
~ (M) -> Granulocytes, mast cells, macrophages, dendritic cells
3) Mature cells
- Differentiated from progenitor cells
What happens at the thymus?
- T cell development
- Precursor cells from the bone marrow migrates to the thymus for maturation
Where are the secondary lymphoid organs?
- Lymph nodes
- Spleen
- Mucosal lymphoid tissues
How does lymph flow?
- Concentrated at portals of entry
- Immune cells enter through afferent lymphatics and high endothelial venules
- Exits the LN through efferent lymph
- Flow of lymph from tissues to LN ferries material for processing and recognition
When can lymphadenopathy occur?
- Proliferation of immune cells on infection
- Proliferation of tumor cells
- LN that drain the site of pathology become enlarged
What happens at the spleen?
- Filters blood of old and damaged RBC and foreign material
Anatomy of spleen:
- Capsule
- Red pulp (where RBC are destroyed(
- White pulp (where lymphoid follicles and lymphocytes are found)
What are the immune complications of a splenectomy?
- More vulnerable to illnesses caused by bacteria
~ Step pneumonia, H influenzae, malaria
What is the intercellular communication in the immune system?
1) Soluble factors (ie cytokines)
- Has widespread effects on susceptible cells
2) Cell-cell contact
- Targeted effects on specific cells
What are cytokines?
- Immunological hormone that change the function of the same or another cell
- Chemokines attract cells along a gradient from low to high concentration
What are the actions of cytokines on cells?
1) Autocrine
- Acts on itself
2) Paracrine
- Acts on nearby cells
3) Endocrine
- Enters circulation to act on distant cells
How are WBC analysed?
Fluorescence flow cytometry (FFC):
- Forward scatter (more scatter intensity, more cell volume)
- Side scatter (provides info about the internal cell structure, eg nucleus and granules)
- Side fluorescence (amount of nucleic acids i the cells)
Serum vs plasma?
Plasma - w/ clotting factors, achieved if anticoagulant is added to blood
Serum - no clotting factors
What are some possible reasons of a low WBC count?
- Viral infection
- Severe bacterial infection
- Bone marrow suppression caused by treatments
