Lecture 6: Immune I Flashcards
Innate immune components
- Physical barriers (skin, mucus, hair, BBB)
- Chemical barriers (sweat, acid, urine, tears, etc.)
- Cellular + humoral innate immunity
Factors released by PMN phagolysosomes
- Myeloperoxidase (anti-bacterial toxin)
- Lysozyme (cell wall degradation)
- Defensins (cell memb. disruption)
Summary of immune response
- Microbe entry
- PRR detection
- DC/PMN/macrophage ingestion + cytokine production
- Microbes in blood are opsonized/killed by complement
- Adaptive response initiation
Functions of complement
- Cytolysis (MAC)
- Inflammation
- Opsonization
Antigens
Peptides, polysaccharides, lipids, nucleic acids that trigger immune responses; peptide Ag’s undergo processing + MHC presentation
5 important features of MHC
- Broad specificity (1 MHC binds many peptides)
- Only binds peptides (best for T cell responses)
- Only displays 1 peptide at a time
- V. slow dissociation rate (presentation lasts long enough to find matching T cell)
- Surface expression req. bound peptide
Dendritic cells
Pro APCs; messengers between innate/adaptive immunity. Migrate to lymph nodes on activation.
TCRs/BCRs
Highly diverse/specific receptors that must be able to :
1. Detect ext. Ags -> trigger cell response
2. Recognize large variety of Ags
3. Distinguish between closely related Ags
Generation of TCRs/BCRs
Somatic gene recombination, pos. + neg. selection
Good and bad of immune cytotoxicity
Good: destroy pathogen-infected cells, cancer cells
Bad: GvH disease, transplant rejection, autoimmunity
NK cells
- Don’t req. Ag presentation for effector function
- Release perforins, granzymes to induce apoptosis
NK cell methods of killing cells
- Perforin/granzyme release
- Fas binding to FasL (death receptor)
- Granulysin
- Ab Dependent Cellular Cytotoxicity (ADCC)
Serial killing cytotoxic cells
All cytotoxic cells move from 1 cell to the next; v. efficient
Cytokines
Immune messenger molecules produced transiently by many cells
Effects of cytokines are:
- Pleiotropic (1 cytokine -> diverse activities in many cell types)
- Redundant (multiple cytokines -> same activity)
Cytokine categories
Pro-inflam.: IL-1, IL-6, TNF
Anti-inflam.: IL-10, TGFβ
GF: IL-2 from CD4+ T
IFNs: IFNα/β = antiviral, IFNγ -> macrophages
Chemokines: IL-8
