What is the principle protective immune response against bacteria?
specific antibodies that opsonize bacteria for phagocytosis by macrophages and neutrophils
What can specific antibody and complement do to gram negative bacteria vs gram positive bacteria?What do specific antibodies do with toxins?
- gram negative bacteria=lyse
- ex. neisseria meningitidis
- antibody, complement, phagocytosis
- gram positive bacteria=opsonize
- ex. streptococcus pneumoniae (antibody to capsule) —require both antibody and complement
- ex. staphylococcus aureus - Neutralize toxins
ex tetanus toxin
-ex. streptococcus pyogenes
How do cells protect against intracellular bacteria?
cell mediated
-Th1–> CD4 cells that activate macrophages by the production of cytokines
What is a disease that uses the TMMI response?
Mycobacterium tuberculosis
What type of microbes are viruses? How does the immune system respond?
Intracellular
- Innate immunity against viruses: cytokines and NK cells
- Adaptive immunity: Specific Cytotoxic T cells
- Specific antibodies, synthesized prior to T cell mediated killing of infected cells
What cells are there at day 2,3,7?
2=neutrophils/mac
3=NK
7=T cell
When is IgM present?IgG
IgM-
3-4 days
peaks at 2-3 weeks
IgG
5-7 days
can persist longer
What mechanisms combat viral infections but not bacterial infections?
cytotoxic lymphocytes-
natural killer cells
interferons(non virally infected host cells-mechanism:cellular anti-viral state)
What happens in diseases caused by exotoxigenic organisms like *clostridium tetani) ?
Eliminate invading organism and neutralize toxin
-if does not block toxin-toxin-blocks inhibitory neuron leading to chronic muscle contraction
What are extracellular organisms?
Bacteria
Eukaryotes
-single celled (fungi)
-multicellular (parasites)
What are intracellular organisms?
Bacteria
protozoa
viruses
What does IgA protect from?
organisms that infect mucosal surfaces
-Neisseria gonorrhea
How are fungi taken care of? What is an example of a fungus?
phagocytic cells
-cytokine activated phagocytosis
-Candida albicans
Schistosoma mansoni causes infection of the gut, what is the response of the immune system to parasites?
- antibody directed complement attack
- Antibody dependent cellular cytotoxicity (ADCC)–>mediated by eosinophils
- innate immunity is generally ineffective
Viruses evoke every form of immunity? What are some ways?
- enveloped viruses can be damaged by complement
- phagocytes can take up and destroy antibody and complement coated viruses
- Infererons, NK cells, antibody, CTL
What produce the different interferons?
- INF-alpha=leukocytes
- INF-beta=any cell in the body
- INF-gamma-Th1 cells (type 2) -produced as a cytokine by T cells and activates macrophages to enhanced level of cytotoxicity
What type of INF does a leukocyte or fibroblast release?
Type 1 IFN (alpha or beta)
-infuse to the surrounding cell and produce proteins that prevent the synthesis of viral proteins
-antiviral proteins-a synthetase and a protein kinase
What two enzymes does interferon synthesize?
- synthetase
- catalyzes the polymerization of adenine
- activates ribonuclease to degrade viral mRNA - protein kinase
- transfers phosphate group to initial factor EIF-2 that is involved in protein synthesis
- viral mRNA remains untranslated
- viral mRNA attacked by ribonucleases and degraded
