Chapter 5, innate immunity Flashcards
Innate immunity can be broken up into 3 divisions, name and explain.
1) physical- skin/mucus
2) chemical- stomach acid, lysozymes, defensins, sebum
3) cellular- cells with TLRs or NOD like receptors
Give some general characteristics of antimicrobial peptides, in addition, give examples and also where they can be found
-specific to certain organisms, + charged because more bacterial cell surfaces are - charged, can penetrate bilayers & form pores and cause gradient dissolution inducing cell lysis.
found on skin, saliva, tears, mucus membranes
-eg: psoriasin–> on skin, inhibits E. Coli but not S. Aureus, prevents infection when skin is cut
sebum, etc.
What exactly is complement? How are some ways in which it becomes activated?
Activated by immunoglobins and PAMPs. It is a collection of proteins that aggregate and form the MAC (membrane activated complex), this in the end causes pores on cell surface and induces lysis. In addition it opsonizes phagocytes and induces inflammation.
Give the stepwise approach to phagocytosis.
bacteria grabbed by pseudopodia, ingested bacteria called a phagosome, phagosome fuses with lysosome and then digested, digested material released from cell and some epitopes are presented on cell surface.
What are ROS and RNS?
Reactive oxygen/nitrogen species that can also kill pathogen in phagocytes.
What are Toll like receptors? Where were they discovered from? Name 3 characteristics of them.
A type of PRR, recognize extracellular PAMPs, the Leucine rich domain binds to PAMPs, different subtypes recruit different adapter proteins which results in a different signalling cascade.
Discovered in Flies, crucial for development of dorsal and ventral axis, a mutation in it made it prone to fungal disease.
What are CLRs?
What do they recognize?
c-type lectin responses, recognizes cell wall components on bacteria and fungi.
What are RLR’s? What do they recognize?
RIG-like responses, recognize viral double stranded RNA, trigger antiviral interferon responses (cytosolic)
What are NLR’s? What do they recognize? What do they activate?
Nod like receptors, recognize intracellular PAMPs, activates Caspase-1 protease which induces apoptosis and Caspase 1 cleaves Interleukin 1 and 18 to active forms and causes their release.
PRR summary: name 5 things they activate
defensins, type 1 interferon, cytokines, chemokines, enzymes.
What are the hallmarks of inflammation and what are the physiological “steps”
swelling, redness, heat, pain, loss of function.
Steps are increased vasodilation to allow more blood to move into area, increased vascular permeability, increased accumulation of fluid that is full of cytokines and chemokines
What is extravastion and diapedesis?
What allows for weak binding to endothelium?
What allows for rolling and what stops the rolling?
When neutrophils and leukocytes adhere to endothelial cells and pass through capillaries into tissues. Rolling occurs using selectins and CAM (cell adhesion molecules) allow for loose connection to endothelial cells.
Integrins on the endothelial cells bind to CAMs and prevent anymore rolling when the cell reaches its destination.
What causes Acute Phase Responses? What is synthesized as a result?
induced by cytokines IL-1, TNF-alpha, IL-6 and releases AMP, Complement
What can Nk cells recognize and what are 2 things they do when activated?
recognize infected cells, cancer cells and other stressed cells. Upon activation, they may directly kill the altered cell or produce cytokines that induce the adaptive response.
What are some ways the innate immunity can be compromised?
defects in PRRs cause higher infection rate, or if they are activated for too long, lots of damage to healthy tissue. Pathogens have ways of avoiding detection by hiding PAMPs, blocking PRR’s signals, evading phagocytes , etc
