Immunology 2 Flashcards
antigen
any substance that can induce an immune response (B or T cell immune response)
2 main categories of antigens
infectious (multiply) and non infectious
size of antigens and strength of immune response
- large antigen: strong immune response (bacterial toxins, viruses, protazoal membranes, hormones, venoms)
- small: poor response
- very small: no response
antigen complexity and antigens and strength of immune response
most complex = good immune response
* proteins
simple substances = poor antigens (do not induce strong immune response
* lipids, polymers
antigen stability and strength of immune response
more stable/less flexibility= stronger immune response
ex: flagellin are flexible
antigen degradibility and strength of immune response
high degradability = poor immune response
non degradable = also poor antige (steel pins, plastic heart valve implants)
needs medium degradibility to be good antigen
antigen foreigness and immune response
more foreign = stronger response
remember immune system differentiates self vs non self
antigen concentration and immune response
low concentration = T cells unresponsive = tolerance
moderate = good immune response
excessive concentration = T and B cells unresponsive = tolerance
epitope (antigenic determinant)
region of the antigen where the immune system (antibody) acts (binds) on it
hapten
- small molecule that by itself cannot induce an immune response
- can induce strong response when bound to protein
binding of hapten to a large molecule (eg protein) = immune response
cross reactive epitopes
common epitope found on different antigens
ex: brucella and yersenia
ex: molecular mimicry: share epitope between microbe and “self”
which part of the immune system deals first with antigens and handles >95% of them?
innate immune system (non specific)
physical barriers (1st line of defense)
- skin
- GI system
- respiratory
- urogenital
- mammary gland
chemical barriers (first line of defense)
- lysozyme
- complement-C
- lysins
- chemokines
- opsonins
- acute phase proteins
skin as an physical and chemical barrier
- sebum from sebaceous glands (low pH, toxic to pathogens)
- natural desquamation (sloughing off)
- non pathogenic bacteria occupy surface of skin
mouth as a barrier
has saliva
flushing action (spitting out)
stomach and intestine as a barrier
- low pH
- lysozyme
- normal bacterial flora (secrete acids, aid in digestion, compete for space, regulate health/disease)
urogenital tract as a barrier
urine:
* flushing action (urination)
* low pH
vagina:
* epithelium rich in glycogen: promotes growth of lactobacillus- makes lactic acid
urogenital tract as a barrier
urine:
* flushing action (urination)
* low pH
vagina:
* epithelium rich in glycogen: promotes growth of lactobacillus- makes lactic acid
respiratory tract as a barrier
- suspended particles cleared by tubulence (bumps pathogens against mucus)
- walls of upper resp tract has mucus (produced by goblet cells, has lysozymes and slgA)
- alveolar macrophages
- ciliary action
mammary glands as a barrier
flushing action
lacteins
* lactoperoxidase
* lysozyme
* lactoferrin
Complement (C’)
- complex series of proteins (many are enzymes/proteases)
- can bind to antibody or work independently
- consists of ~30 proteins starting with C (ex C1)
C3 and C5
very important in inflammation and eliminating antigen
Where are complement components produced?
- liver (parenchyma)
- marcophages
- monocytes
- GI, urinary tracts
- neutrophils store complements
main functions of complement
- complement mediated chemotaxis
- complement mediated oponization
- complement mediated inflammation
- removal of immune complexes
- regulation of immune system
complement mediated oponization
- complement binds to bacteria
- macrophages with receptor for the complement bind to complement-bacteria complex
- macrophage eats complement and bacteria (more efficient)
