How to fight infection and the body's response Flashcards
Describe the barriers the body has to infection
Antimicrobial factors in salive Mucus and cilia Skin pH Acid Flushing urinary tract
What is phagocytosis?
Cell recognizes and binds to pathogen. This activates the cell to ingest the bacteria (the leading edge and pseudopodium engulf bacterium). Inside the cell, oxidative burst kills it
How does the body respond to bacterial infection?
- Bacteria enter tissue
- Innate cells have PRRs on surface to bind to PAMPS on bacteria
- Bacteria phagocytosed
- At the same time, macrophages release pro-inflammatory cytokines and chemokines
- Cytokines IL-1 and TNF-alpha and chemokine CXCL-8 are released by macrophage
- Mast cells have PRRs on surface and can be activated by proteins
- When activated, mast cells degranulate and release contents into tissue
- Causes blood vessels to swell and become leaky
- Tight junctions between endothelial cells separate - allows contents of blood to get into tissue and immune cells to enter site of infection
- Neutrophils first cell to enter site of infection - engulf and phagocytose bacteria (oxidative bursts and enzymes)
- Complement and c-reactive protein drawn into wound
- Proteins enter area to make bacteria clearer for phagocytes
- Dendrites engulf pathogens and then move to lymph vessel, taking pathogen to lymph node - macrophages can do this too
- In lymph, t-helper cells are waiting to be activated. Dendritic cell enters and breaks down microbe, presenting a portion of in MHC II
- Recognized by T-cell receptor on CD4 helper cell
- In combination with co-signaling process, activates T-helper cell
- Effector T-helper cell replicates and clonally expands
- Activates B-cells to produce antibodies
- IgM enters wound
Which cytokines are released by macrophages?
IL-1 and TNF-alpha
Which chemokine are released by macrophages?
CXCL-8
What happens to mast cells when they are activated?
Degranulate
What do cytokines do?
Communication between cells - can be pro/anti inflammatory
What are interleukins?
Target leukocytes
What are interferons?
Antiviral response
What are chemokine?
Mediate chemotaxis
What are the three mechanisms that can activate complement proteins?
Alternative, classical and Mannose-binding lectin pathway
What is the alternative pathway to activate complement proteins?
Complement protein binds to microbe itself
What is the classical pathway to activate complement proteins?
Antibodies bind to bacteria which activates the pathway
What is the MBL pathway to activate complement proteins?
MBL binds to microbe initially to initiate pathway
What is the common result of activating complement proteins?
C3a is produced to instigate the inflammatory process
What does C3b do?
Opsonize and phagocytose microbes
Where are acute phase proteins produced?
Liver
Which chemicals signals the liver to produce acute phase proteins?
IL-6
What doe acute phase proteins do?
Opsonize
Activate complement cascade
What do TH2 cells do?
Activate B-cells to produce plasma cells to produce antibodies
How are B-cells activated?
- Activated when antigen presented to T-helper cell
- When T-cell activated, B-cell is activated too
- Co-stimulatory signals and cytokines enables B-cells to become active
- B-cells clonally expand
- B-cells can differentiate into plasma cells or memory cells which reside in lymph
What is isotope switching?
Producing different types of anitbody
What is the first antibody to be produced?
IgM
What is opsonisation?
Highlights pathogen to phagocyte
Helps phagocytosis
Important for encapsulated bacteria and viruses
