I&D Flashcards
What are the 4 main immune compartments? Which ones use cytokines and chemokines?
Innate: complement, phagocytes
Adaptive: B cells and T cells
Phagocytes and T cells use cytokines and chemokines.
What is the end result of complement? How does it happen?
It’s the landmines of the innate system. After triggering several activation events –> end up in “explosion”. Major role is opsonization (coating of bacteria for phagocytosis) and formation of membrane attack complex (MAC)
What happens if the complement doest work?
Since complements creates opsonization, when it’s defective lots of encapsulated bacteria due to inefficient opsonization and phagocytosis. So we get lots of infection by encapsulated bacteria (like strep)
What are some unique features of phagocytes? How are they related to T-cells?
- They move to the site of infection through tissue like marines and they are first deployed to the battle
- They eat, digest and present antigens to T-cells, T cells in turn required to have MHC to actually recognize peptides presented
What happens if phagocytes doesnt work? What disease can it cause?
Lots of infections by catalase + organisms, soft tissue abscesses, lymphadenitis and poor wound healing. Causes Chronic Granulomatous Disease ( defective NADPH oxidase -important for innate immunity) and unable to kill catalase + bacteria
What is the of of B cells?
B cells are like air force: the main role is to deploy a/b(immunoglobulins) that are like cruise missiles. Can deploy at or near site of inflammation or can be distant
What happens if B cells and A/B dont work?
Recurrent bacterial sinopulmonary infections
What is the role of T cells? What are the roles of three different types?
Known as generals, assassins and psychologists of the immune system
- CD4 - helper T cell: directs immune system where to go
- CD8 - cytotoxic T cells kill cells infected with intracellular pathogens like viruses, fungi, etc
- regulatory T cells control and modulate immune responses - modulates autoimmune and immune system, have to keep cells under control
What if T cells don’t work?
- cant generate effective a/b response
- severe viral infections (Herpes Simplex virus type 5(CMV) and type 4 (EBV))
- severe fungal infection
- autoimmunity
What do we mostly have issues with during one of the compartments absent?
Complement - encapsulated bacteria
Phagocytes - Bacteria, Fungi, Molds
B cells - bacteria
T cells - viruses, fungi, bacteria
What are the two goals of micro?
see
bacterial envelope: difference for G+ and G- bacteria? Why is this difference in cell wall assembly important?
One cell membrane surrounded by a thick cell wall: G+
Additional outer membrane: G-
Important because its an antibiotic target
What does cell envelope structure determine?
cell envelope structure Determines the gram stain
What are bacterial appendages and capsules important for?
colonization, attachment, movement. Its a part of pathogen factor
What are the 4 appendages in bacteria?
- flagella -colonize
- Pili/fimbriae - attachment are virulence factors
- specialized secretion systems-syringes to inject substances into the host
- capsules - external mucoid polysaccharide layer avoids immune recognition and phagocytosis
How does mucosal clearance happens? What are some barrier in mucosa?
tight junctions and mucus barrier forms a barrier
movement happens with cilia and peristalsis
What are the ways pathogens evade mucus clearance?
- Viruses have specialized molecules that attach to specific host-cell receptors (our body has receptors that help virus-ligand interaction, like sialic acid (for influenza) is a receptor our body has) Note! The physical barrier isn’t compromised. Its just a normal receptor
Whats is the other way other than receptors that pathogens can enter?
defective epithelia barrier!
skin defects, anatomic defect (Tracheoesophageal fistula), mucosal defects (chemotherapy causes mucositis)
how do pathogens cross the epithelial barrier?
Via target cells involved in immune surveillance
- dendritic cells - HIV (macrophages and DC on the surface of the membranes bind viruses and shuttle into lymph nodes
- Intestinal M cells - Salmonella
Does infection have to involve invasion?
NO. they can attach to cilia and use toxins to cause damage or they can attach and just steal nutrients
what are the 5 ways to avoid immune detection and
- intracellular invasion
- capsules to avoid phagocytosis
- antigenic variation
- immune modulation (go through)
- residence in immune privileged sites (VZV in sensory neurons in dorsal root ganglia and trigeminal ganglia)
How do bacteria and fungi steal nutrients? Whst do thry acquire?
using toxins. Micronutrients: iron (essential metal nutrient), sidephores (high-affinity iron chelating compounds), digestive enzymes
What are the three complement systems? What are they activated by?
- Classical pathway - activated by immune complexes
- Lectin pathway - activated by Pathogen Oligosaccharides -they recognize specific oligosaccharides
- Alternative pathway - activated by pathogen surfaces
