Overview of Innate/Adaptive Immune System Flashcards
Innate Immune System
- Epithelial Barriers
- Phagocytes
- NK Cells
- Complement
Epithelial barriers
Produce natureal antibiotics
i.e. defensin
Phagocytes
Macrophages, PMNs, Dendritic Cells
Neutrophils DO NOT communicate to adaptive immune system.
These cells do not need to be activated; always available
Complement
Major humoral effector mechanisms
Family of proteins that exist in body fluids
Consists of
* Classical Pathway (uses peices of adaptive)
* Alternative Pathway
*Mannose Binding Lectin pathway
NK Cells
Bone marrow derived cells Involved in viral infection Derived from lymphoid progenitor cells Dont need series of activation Recognize immuno comprimised cells that are not expressing MHC I
PRR and DAMP/PAMP
PRR = Patern Recognizing Receptor PAMP = pathogen associated molecular pattern DAMP = Damage associated molecular patter
PRR recognize PAMPs/ DAMPs
Clonal Selection
When T-helper cell gets activated by MHC II the cell rapidly divides
Each cell has SAME specificity for antigen
B cells need _____ to undergo clonal expansion
recognition of antigen via surface MHC II by T-helper cell
Extracellular Pathway
B cell and their products are hummeral immunity
Intracellular pathway
Internal pathogens like virus
Cytotoxic T-cell recognizes MHC I
Cytotoxic T-cell expresses CD8+
Cytotoxic T-cell kills infected INTRACELLULAR cell
HIV mechanism
HIV docs on CD4+ T-helper cells
HIV infects Th and inhibits production of cytotoxic T cells and Plasma cells from producing antibodies
Examples of PRRs
TLR: toll like receptors 3: Recognizes DS RNA (endosomal) 5: Recognizes Flagella 4: Recognizes LPS TLRs are upregulated by NFk-B
NOD: (Cytosolic) Nuclootide-binding oligomerizing domain
Activated by stress proteins within the cell
Mannose Receptor: only recognizes mannose as terminal sugar (bacteria put manose on terminal sugar
Activates manose binding lectin domain
Activation of NK cells
KAR: killer activating receptor
recognizes stress proteins due to viral, tumor transformations
binding of receptor activates NK cell and kills target
i.e. NKG2D
CD16 of NK cell binds to Fc Portion of antibody on virus
CD16 is antibody dependent!!
Inhibition of NK cells
Killer Inhibiting Receptor (KIR)
Receptor engages MHC I and inhibits activation
T or F
PMNs are professional APCs
FALSE
PMNs ARE NOT ANTIGEN PRESENTING CELLS
Professional APCs
Macrophages, Dendritic Cells - phagocytic
B cells- pinocytic and then present antigen
MHC II
Made in ER
Made up of 2 polypeptide chains alpha & beta
embedded in membrane
multi-geneic complex
alpha1, beta 1 domain binds to bacterial peptide
anchor site binds 15-20 AA of bacterial peptide
In ER MHC II is inactivated by Invariant chain
Activation of MHC II
In ER MHC II is covered by invariant chain
As MHC II migrates to late endosome invariant chain gets digested to small fragment that remains on MHC II called CLIP (CLass II Invariant chain associated Protein)
HLA-DM removes CLIP from MHC II to interact with digested bacterial polypeps in late endosome
Genese of MCH II
HLA Genes (Human Leukocyte Antigen)
DP, DQ, DR
get two sets (one mom, one dad)
each gene is codominantly expressed
each loci has two genes one for alpha portion and one for beta portion
genes are constitutively expressed in APCs
Cell mediated
Intracellular Pathway
Utilizes MHC I / CD8+ cells
Activation of MHC I
Viral poly-peps (pp) get ubiquinated and taken to proteosome for degredation
Degraded viral pp get transported into RER via TAP (transporter associated-antigen presentation) (ATP Dependent transporter)
MHC I binds to viral PP and expresses on cell surface to get destroyed
MHC I binds to up to 9AA of viral PP
cells make MHC I constitutively
Genetics of MHC I
HLA-A, HLA-B, HLA-C
On chromosome goes B, C, A
Multigeneic, multi-allelic and codominant
genes code for alpha 1, 2, 3 portion
Beta 2 microglobulin
Attached to alpha1 portion
Coded for on another chromosome but REQURED for transport of MHC I to outside of cell
Ternary Complex
Complex that contains alpha1, alpha2, alpha3 from HLA-A, HLA-B, or HLA-C with beta2 Microglobulin
(MHC I)
The MHC I is also bound to viral PP
Bacterial Poly Peptides that create response are called ________
immunodominant
Why is it difficult to find a donor/ recipient in regards to MHC I?
Each person expresses at least 6 different MHC I genes
i.e. HLA-B26, HLA-C3, HLA-A2 from mom
HLA-B3, HLA-C16, HLA-A9 from dad
Who expresses MHC I?
Cells that are infected with viral pp express MHC I with viral pp bound
Other HEALTHY cells express MHC I with self pp and are not destroyed
Cytotoxic T cells with CD8+ recognize infected target cell with MHC I and KILL
