intro to immunology Flashcards
functions of immunity
immune defense: how human/animal respond to pathogens
immune homeostasis: how immune system balances
immune surveillance: monitoring immune system => activated if something happens
innate immunity aka active
immunity from birth
- very broad defense
- patter recognition, but no specificity
- no memory
- temperature: increase temperature, pathogens can’t survive
- pH: pathogen has pH 7 but our stomach is acidic
- barriers (skin, feathers)
- microflora: on any surface on skin, mouth, nose etc.
- cilia: microorganisms provide physical layer of protection and environment is hostile to pathogen
- cells (neutrophils, macrophages)
- complement
- serum proteins (in blood that immediately take action)
adaptive immunity aka acquired immunity, also passive immunity
acquired, takes time
- developing certain response to pathogens
- mediated by lymphocytes
- memory
- specificity
- specialization
ex: immunity from vaccine
- B cells (from bursa of Fabricius or bone marrow) => generate antibody IgM, IgG, IgE, IgA
- T cells (from thymus)
- killer and helper T cells
what is the most abundant cell type in the blood
neutrophil
mechanisms of immunity
barriers (innate)
- physical: skin and mucosa
- chemical: antimicrobial substances in secretion of skin and mucosa
- biotic barrier: normal flora existing on the surface of skin and mucosa
- anatomic: blood brain barrier, blood placental barrier (protect fetus), blood thymus barrier (where T cells are)
humoral factors (innate)
- complement
- lysozyme
- interferons
- C-reactive protein
cells participating in innate immunity
phagocyte: endocytosis and phagocytosis mononuclear phagocytes
- monocytes
- neutrophils, eosinophils: phagocytes that identify and kill pathogens
- natural killer cells (NK)
- dendritic cells
- basophils
- mast cells
myeloid cells of immune system
neutrophil
function: phagocytosis and activation of bactericidal mechanisms
- polymorphonuclear
- phagocytosis: specialize in the capture, engulfment, and killing
- short life span (hours)
- work in anaerobic conditions (damaged tissues)
- massive migration to site of infection => first responder once they receive signal
monocytes (blood)/macrophage (tissue)
- phagocytosis and the killing of microorganisms => activation of T cells and initiation of immune response
- there are tissue-specific macrophages => “resident macrophage”
- antigen-presenting cells
macrophage
function: phagocytosis and activation of bactericidal mechanisms, antigen presentation
- Elie Metchnikoff coined the term macrophages and first described phagocytosis in starfish embryos
- long lived
-first cell to sense invading microorganism - secrete the cytokines that recruit neutrophils and other leukocytes
dendritic cell
function: antigen uptake in peripheral sites, antigen presentation
- in the blood and tissues - mature and migrate to lymph nodes
-distinctive star shaped- act as cellular messengers that call up an adaptive immune response
- antigen presentation in lymphoid organs
immature dendritic cells reside in peripheral tissues -> migrate via lymphatic vessels to regional lymph nodes -> mature dendritic cells activate naive T cells in lymphoid organs such as lymph nodes
an innate lymphocyte
- B lymphocyte is antigen-presenting cell
- NK cells do not require prior immunization or activation
- attach to target cells
- cytotoxic granules are released onto surface of cell
- effector proteins penetrate cell membrane and induce programmed cell death
- 2 functions: kill virus infected cells, impede viral replication by secreting cytokines
once virus gets into cell => has to kill whole cell
pathogen associated molecular patterns (PAMP)
allows the immune cell to recognize the pathogen as infectious agent
pattern recognition receptors (PRR)
define the responsiveness of the host cell (receptor from host recognize different types of pathogen)
TH1 activation of macrophage
activates infected macrophage to make it more powerful to fight the antigen
