What are mast cells & what is their role?
Resident cells which are involved in wound healing, defence, allergy & anaphylaxis. Contain granules of histamine and heparin
What is the role of dendritic cells and where are they found?
Initiate innate immune response - found in lymphoid tissue and in the blood stream. Capture and process antigens
What are macrophages and what is their role?
Antigen presenting cells which also phagocytose >1 pathogen at a time. Lyphokines stimulate.
What are NKCs?
Cells which kill tumour cells - antigen not needed here
Name the 3 granulocytes - what are their roles?
- Basophils contain granules of heparin and histamine. Degranulation of these in allergic response. Release IgE too
- Eosinophils - antihistamine role --> release histaminases. Kills nematodes
- Neutrophils --> diapedisis to site of inflammation/infection + phagocytosis of 1 or 2 pathogens at a time
Describe the classical pathway of the complement system
- Antibodies bind to antigens on a microbe, C1 then binds to AB and is activated to cleave C4 --> C4a and C4b.
- C4 b binds to surface receptor on microbe and C4a degranulates elsewhere.
- C1 then cleaves C2 into C2a and C2b (this binds to C4b to produce C3 convertase enzyme which cleaves C3 into a and b parts).
- C3b = opsinisation on microbe - immune system attacks
What are cytokines and what do they do?
Cellular signalling proteins which bind to receptors intra/extracellularly to initiate a signalling cascade e.g. to initiate transcription in the nucleus of a cell. Also inflammatory mediators
Name the gross parts of the spleen and explain their general function
Red pulp = removes/destroys damaged RBCs. White pulp = acts like lymph node --> macrophages here for phagocytosis of pathogens. Present antigens to T-helper cells which produce cytokine. B cell amplification to generate ABs against the pathogens
What is MAC and what is its role in immune response
Membrane attack complex - forms a transmembrane channel in the cell wall of a pathogen and causes influx of fluid = cell lysis and death
What can mitochondrial damage lead to?
ATP depletion --> cell death
What are the mediators of the vascular changes which happen in inflammation? What happens to the speed of the blood flow here - why?
- Histamine and NO cause vasodilation to increase the blood flow to the site of inflammation.
- Histamine and cytokines increase the permeability of the vessels (high protein exudate --> swelling)
- Blood flow slows to allow transmigration of the leukocytes
What are the 5 steps of leukocyte traveling to the site of inflammation?
- migration towards chemotactic signal
What affect do chemokines released from macrophages have on leukocytes during inflammation?
Chemokines activate the integrins on the leukocytes which make them 'sticky'
What are the systemic consequences of acute inflammation? (6 listed)
Name 3 causes of chronic inflammation
- persistent infection
- prolonged exposure to toxic agent
What are granulomas?
Collection of epithelial histocytes - specialised macrophages in a collection. Can have a necrotic core - dead cells and pathogens