Intro + Viruses Flashcards
What are the barriers to infections?
-Stratum corneum: Microbiome barrier, chemical barrier (pH, antimicrobial peptides, lipids, electrolytes, urea, amino ac., lactate)
-Epidermis: Tight junction, adherens junctions, Langerhans and CD8 T cells
-Dermis: Macrophages, Mast cells, ILC, CD4 T cell, DC, NKT cells
What is the Microbiome and how does it effect the immune system?
Collection of microbes living in and on our body
-> Commensal: microbes living in and on us and cause no harm (we benefit bc they provide protection against pathogens)
-> Provide homeostasis (metabolic and immune balance)
-> Imbalance or dysbiosis can lead to immune overstimulation and inflammation (dysbiosis due to dietary change, stress, and environmental factors)
What is the first barrier against pathogens?
Barrier immunity: physical (Skin), chemical (low pH, antimicrob. agent, lipids, AAs) , biological (microbiome)
Innate immune responses: Phagocytes
How do phagocytes fight pathogens?
Engulf and degrade, they use germ-line-encoded recognition molecules
(the adaptive immune system uses gene arrangement of receptors, to identify different pathogens)
What parts of pathogens are different from humans?
(Bacteria, fungi, viruses, parasites)
Virus: ds RNA
(ss/ds) DNA in cytoplasm means our nucleus is damaged or there is a virus, but they use our machinery (polymerase, ribosomes)
Bacteria: flagella, peptidoglycan, and LPS for gram neg. bacteria
Fungi: they are commensal fungi in the body
once the microbiota is damaged, they can take over and cause problems
parasites: membrane, proteins, parasitic pathways looks human
What is the adaptive immune system and what are its advantages and disadvantages?
Humoral (B-cells), Cell-mediated (primarily T lymphocytes)
Advantage: very specific
Disadvantage: it takes some time to build up the cell number (5-6 days)
How does Cell-mediated immunity respond?
-Cytotoxic T cells (T cells) kill infected cells to eliminate pathogens
-Helper T cells (Th cells) produce cytokines to regulate both Tc-cells and B cells
How can adaptive immunity respond to pathogens they have never seen before?
Random recombination of the binding site of B and T cell receptors
What is the problem with random recombination?
The receptors eventually target to self antigens
Difference between B cell receptors and antibodies?
Not a lot of difference, once the B cell gets activated it will generate the same version of B cell receptor but without the transmembrane domain
B cell receptors and antibodies can also be called immunoglobins
How are antibodies produced?
Once B-cells are activated they turn into plasma cells, they loose their B cell receptors, they have a lot of ER and ribosome to produce and secrete a lot of antibodies
How are T cell receptors different from B cell receptors?
B cell receptors are scanning for small protein pieces that move around in the area
T-cell receptors are binding to even smaller pieces presented by phagocytic cells, so they use MHC-1 (cytotoxic T cells), MHC-2 (T helper cells)
What does Tolerance mean?
Early deletion (lymphoid organ) of B and T cells that target self antigens
How is immune memory created?
After the primary (first) response the adaptive immune system will leave behind some memory lymphocytes
-> memory lymphocytes are stimulated with the secondary response, resulting in an even greater adaptive immune response
How does the innate and adaptive immune system work together?
-innate systems produce signals (often cytokines) -> stimulate and direct adaptive immune system
-Phagocytes present antigens to the adaptive immune system, to stimulate differentation
