Lecture 2 - Cells & Tissues of the Immune System I Flashcards
What is a major difference between the lymphatic system and the circulatory system?
Lymphatic is an open circuit, unlike the circulatory system
Where do most infections occur? Why is this important?
In the tissue
The tissue fluid is drained into lymphatics, so that the immune system can respond accordingly
Describe lymph circulation
- Tissue fluid drains into lymphatic capillaries
- Travels through lymphatics
- Passes through at least one lymph node
- Draining into subclavian veins
Where are T cells produced?
In the bone marrow, but they develop in the thymus
Which cell is very important for representing what is happening in the periphery in lymph nodes?
Dendritic cells
Describe the structure of a lymph node
- Capsule
- Cortex
- Medulla
- Follicles w/ Germinal centres : B cells
- Paracortex : T cells
- Afferent & efferent lymphatics
Where are B cells found in lymph nodes & white pulp?
Follicle, Germinal centre
Which organs receive lymph?
Lymph nodes
NOT spleen
Which fluids does the spleen receive?
Blood
Describe the structure of the spleen
Trabecular artery & vein
Red pulp: Erythrocytes
White pulp: • PALS: peri-arteriolar lymphatic sheath : T cells • Germinal centre: B cells • B cell corona • Marginal zone • Perifollicular zone
Describe in general the role of the white pulp
Basically like a lymph node; immune response
What is the role of the spleen?
Collects up old, dying red blood cells
What is the rationale for the naming of eosinophils, basophils and neutrophils?
What is the collective name for these cells?
Eosinophils: stain with eosin
Basophils: stain with a basic dye
Neutrophils: don’t stain
These are the granulocytes
What is the general function of the granulocytes?
Phagocytosis
Describe how neutrophils can kill bacteria
- Phagocytosis
- Degranulation
- NETs
Where are neutrophils normally found?
In the blood
They are rarely found in healthy tissue
Where are eosinophils found?
Majority found in the tissues (opposite of neutrophils)
Describe the function of eosinophils
Releases toxic granules that kill parasites Two types of granule: 1. Microbicidal: • Radicals • Toxic proteins
- Immunomodulatory
• Leukotrienes
• Protaglandins
• Cytokines
What are the two types of granules released by eosinophils?
- Microbicial
* Immunomodulatory
What is the function of basophils?
Where are they found?
Granule release:
• Release of histamine from cytoplasmic granules (similar to Mast cells)
• Cytokines
- Role in parasitic infection & allergy (similar to eosinophils)
- Have IgER (similar to Mast cells)
- Role in T cell development
Location
• Recruited out of the blood to the site of infection (similar to neutrophils)
• Are also found in tissue
What is the difference between macrophages and monocytes?
Monocytes: in the blood
Macrophages: in the tissues
What are some features of Mast cells?
- Contain granules; release of histamine (also cytokines)
- Release in response to Fc receptor cross linking
• Have FcER; binds IgE
Where are DCs normally found?
In tissues
What is very important about DCs?
They are innate cells, but they activate the adaptive immune system
