Immune diseases Flashcards
what cells produce mucus?
goblet cells
what cells secrete antimicrobial peptides?
Paneth cells
what are the components of MAC?
C5b, C6, C7, C8, C9
which complement component is recognized by phagocytes? (opsin)
C3b
which complement components act as chemotactic agents?
C3a, C4a, C5a
what is the link of complement with antibodies?
they can form functional complexes with antibodies to facilitate the clearance of antigens by phagocytes
name the types of innate immune cells
mast cells, neutrophils, macrophages, DCs
what do Fc receptors recognize?
antibodies
what is special about PAMPs?
they are essential for the viability of the microbes and cant be mutated
what other than PAMPs can PRRs recognize?
flagella on bacteria, nucleic acid on viruses, GPI anchor on parasites
where can PRRs be found?
innate immune cells and epithelial cells
what does activation of PRRs lead to?
production of cytokines and chemokines that help recruit other immune cells
what do mast cells recognize? with what receptor? leads to what?
IgE antibodies with Fc receptors; activation
2 ways how mast cells help immune response?
- degranulation -> release histamine, proteases, chemotactic factors
- metabolism of membrane phospholipids (arachidonic acids -> prostaglandins + leukotrienes) -> sm contraction and vasodilation
what are mast cells involved in?
type I hypersensitivity (allergic) reaction, neutrophils extravasation, vasodilation
what process do neutrophils go through to participate in the immune response?
extravasation
where can we find neutrophils?
in circulation
what type of agents do neutrophils produce?
antimicrobial agents: ROS, cathepsin G, defensins
what happens if NETs are not cleared up rapidly?
they persist and result in cell damage through enhanced inflammatory processes
where are innate cell macrophages found?
in tissue
where are tissue-resident vs monocyte-derived macrophages from?
tissue-resident macrophages are derived from yold sac or fetal liver.
monocyte-derived macrophages are derived from bone marrow.
what 6 different tasks can macrophages perform?
antimicrobial actions through ROS.
antigen presentation.
antigen/antibody uptake.
wound healing through GF production.
phagocytosis.
bone resorption through osteoclasts.
what are DCs cell called in the skin?
Langerhans cells
what cells do DCs arise from?
monocytes
what is the most efficient APC?
dendritic cell
what are the structure of MHC class 1 and II molecules?
MHc class I = alpha chain + variant beta macroglobulin chain
MHC class II = alpha + beta chain
what are MHC called in humans? where is the gene located?
HLA;
chromosome 6
everyone has different HLA genes except?
except identical twins
what is the only cell that can activate naive T cells?
dendritic cell
where do innate lymphoid cells originate from?
hematopoietic stem cells in bone marrow
name the innate and adaptive immune cells from each lineage
innate myeloid lineage: neutrophil, eosinophil, basophil, monocyte, macrophage, dendritic cells, mast cells, platelets
adaptive lymphoid lineage: t cells and b cells
what is special about NK cells origin
derived from lymphoid progenitor but are innate immune cells
what are the 2 ways how NK cells kill?
- induce apoptosis by producing perforins and granzyme proteins.
- Fas ligand triggers cell death
what can tumor cells downregulate to evade immune regulation? what does this downregulation trigger regarding NK cells?
downregulate MHC class I. decreases the inhibitory signal that the NK cells recives -> activates NK cell -> kill
what does each of the 3 classes of innate lymphoid cells respond to?
ILC1: intracellular pathogens
ILC2: parasites
ILC3: extracellular bacteria and fungi
how is the variable regions of TCR generated? what does this allow for?
from VDJ recombination.
allows for specificity
where do t and b cells differentiate and mature?
both differentiate in bone marrow.
T cells mature in the thymus (become CD4/8 +)
B cells finishes maturation in lymph nodes
name the different subtypes into which CD4+ t cells can further differentiate in peripheral tissue, and their associated cytokine
TH2 cells: produce IL-4. involved in allergies
TH1 cells: produce IFNy
TH17 cells: produce IL-17 (TH1 and TH17 are involved in type IV hypersensitivity and autoimmune diseases)
Treg: TGFB
what happens in the lymph node to complete the maturation of B cells?
b cells enter through afferent lymphatic vessels, proliferate in primary follicles, become germinal centers when in contact with antigen. they fully mature and become plasma cells and exit through efferent lymphatic vessels
2 ways how B cell can activate
- T cell-independent: recognize antigen and BCRs aggregate
- T cell-dependent: through cytokines
antibody receptor produced by naive B cells
IgM receptors
what enzyme helps with variable region hypermutation of IgM receptors?
AID enzyme (activation-induced cytidine deaminase)
what antibodies do plasma cells secrete at a distance?
IgM or IgG
what are antibodies effector functions?
Neutralization of microbes and toxins.
Opsonization and phagocytosis of microbes recognized through Fc or C3b receptors.
Antibody-dependent cellular toxicity: activation of NK cells.
Complement activation to facilitate inflammation and lysis of microbes.
3 types of immune system failures
hypersensitivity, autoimmunity, immunodeficiency
what are the 4 types of hypersensitivity reactions? describe
type I: immediate T cell dependent allergic reaction
type II: antibody specifically recognizes a receptor on cell surface
type III: antibody driven: immune complexes trigger neutrophils activation and inflammation
type IV: delayed t cell dependent reaction involving TH1 and TH17
which cells and cytokines are involved in type I hypersensitivity?
Th2 cells and IL4, IL5, IL13, IGe production
what are the 2 steps of type I hypersensitivity reaction (during secondary exposure)?
- initial response within minutes & mast cells activation
- late phase reaction: cytokines infiltration other cell types
what do mast cells do after the second exposure to allergen (Type I hypersensitivity)
degranulate and release histamine
features of the secondary exposure of type I hypersensitivity?
mast cells, vasodilation, pain, eosinophils recruitment, hyperactive mucous production, platelets activation