Lecture 1: Part 2 Flashcards
Immune response all compountants
Immune response
1) Innate immunity
2) Adaptive immunity
- Humoral immunity
- Cell mediated immunity
Cells of the immune system name
Leukocytes
Innate immune response
- What barriers and cells and systems are used
- Gen mechanism
- How does it respond to repeated exposure
- Uses physical and chemical barriers
- Pahagocytic cells and complement system
- Pattern recognition of general strcutures common in pathogens
- responds the same way to repeated exposures with pathogen
Adaptive immune response
- Cells
- Specificity
- How does it respond the next time a same antigen is presnet
Lymphocytes and antibodies are used
Hiighly specific
Response increases in magnitude with successive exposure to antigen
Stem cells
Hematopoietic stem cell ( HSC):
- All leukocytes derive from them from bown marrow, They mature through a process called hematopoesis
Myeloid stem cells mainly make innate immunity
Lymphoid stem cells mainly make adaptive immunity cells
Major cells of the adaptive immune response
- What cells present antigens?
Dendritic cells bridge innate and immune. Present antigens to lymphocytes: B cells and T cells
Lymphoid progenitor to lymphocytes
self-antigen binding are eliminated
When a foreign antigen interacts with receptor on a mature lymphoyte, gives rise to identical progeny
Progeny go into effector cells and kill
Some lymphocytes are retained to mediate immunological memory
What are APC’S
antigen presenting cells
present antigens to T cell receptors via MHC
Provide signals that stimulate the proliferation and deferentiation of T cells
**Humoral immunity
- antibodies produced by B cells
- Defend and eliminate extracellular pathogens
- Antibodies bind and neutralise pathogens for phagocytocis
Cell-mediated immunity
- Tcells
- Defend and eliminate intracellular pathogens
- Some T-cells can activate macrophages to kill phagocytosed microbes or can destroy directly
Pathogenic bacteria are combated by different host mechanisms depending on where they reside
Extracellular:
- Mainly avoid immune destrcution by antibodies the complement system and antimicrobal peptides
Intracellular:
Mainly evade immune responses by seeking shelter in phagocytes
NK cells and T cells
PAMPS and PRR’s
Pattern recognition receptors (TLR’S)
Pathogen associated molecular pattern (LPS and peptidoglycane)
Some pathogenic bacteria avoid detectionby PRR on immunce cells by shielding PAMPs
Gram - containd LPS in their outer membrane which activate TLR-4
- Lipid A with less acylated forms have been reported to be poor stimulators of TLR 4’s so can now evade immunity
Gram + bacteria contain peptidoglycan in their cell wall which activates TLR-2
Blocking detection of these PAMPS can allow bacteria to evade being detected
What is antigenic variation?
- Explain
- Give example
Mechanism by which pathogens alter their antigenic surface proteins in order to evade the adaptive immune system
Results in a Heterogenic phenotype of a population (The nonconformists show an expression profile partially different from that of the remainder of the population)
In S. pneumonia, antibodies against one type wont rexognize another type cause different proteins in capsuels
pili use for evashion
Pili are major antigenic targets in Neisseria cell surface
Gene locus coding for pilus (PileE) undergoes DNA recombination with piliS (no promoter) to generate a constantly shifting pilus for display on the bacterial surface
