Macrophages, Cytokines & Inflammation Flashcards
What immune cells are involved in adaptive immunity?
B cells - Antibodies
T cells- CD4 and CD8 T cells
What immune cells are involved in both innate and adaptive immunity?
Natural killer T cells
Gamma delta T cells
Dendritic cells
What immune cells are involved in innate immunity?
All not yet mentioned, e.g:
Mast cells
Macrophages
Neutrophils
etc
What are the granulocytes?
Neutrophils, eosinophils and basophils
What are eosinophils?
Eosinophils are involved in parasitic infections and play a role in allergic reactions.
- release toxic granules to destroy parasites
- modulate inflammatory responses.
What are basophils?
- Rarest granulocyte
- Involved in allergic reactions and inflammation.
What are neutrophils?
First cells to arrive at site of injury or infection in response to chemokine produced in local tissue (e.g. by mast cells)
When do neutrophils produces NETs?
When the microorganism is too large to be ingested and phagocytosed, they can produce NETs formed by DNA fibres and proteins from the granules
What are the main functions of macrophages?
- Removal of apoptotic cells
- Production of inflammatory and repair mediators - resolution of inflammation
What is the main role of dendritic cells?
- Antigen presentation
- Phagocytose and digest microbes
- Transport antigenic fragments to lymphocytes (T and B cells) in the lymph node
What are the two different types of macrophages?
- Tissue-resident
- Infiltrative monocyte-derived
Monocyte derived can become tissue-resident over time
What 3 cells can monocytes differentiate into?
- Macrophages
- Inflammatory dendritic cells
- Osteoclasts
What turns a monocyte into a macrophage?
M-CSF and local signal
What are the 3 different specialisations of macrophages?
M1
M2a
M2b
What is the main role of M1 macrophages?
Type 1 inflammation
What is the main role of M2a macrophages?
Type 2 inflammation
Repair
What is the main role of M2b macrophages?
Immunosuppression- important in inflammation resolution
What are defensins?
Small cysteine-rich proteins that are antimicrobials active against bacteria, fungi and viruses. They are produced by innate cells
Why do defensins not harm host cell membranes?
Our own cell membranes are protected by abundant covering of siliac acid, which prevents defensin binding
What immune cells are primarily involved in acute inflammation?
Neutrophils dominate
Acute inflammation lasts a few minutes to a day
What immune cells are primarily involved in chronic inflammation?
Macrophages and lymphocytes
Chronic inflammation lasts weeks to years
What are some ways in which inflammation induces its own resolution?
- Short half-life of cytokines
- Some cytokines inhibit their own production
- Macrophages produce resolvins, which induce tissue repair
What is an example of a cytokine negative feedback?
IL-1 induces cortisol which feedback inhibits the production of further IL-1 (immune suppression/resolution)
Give an example of how cytokine production is regulated
Transcriptional regulation- controlled by transcription factors like AP-1 and STATs
