antibacterial immunity Flashcards
pathogens can directly harm host tissue, but in some cases _____ can cause damage and disease in host
aggressive immune responses
examples of extracellular bacteria
e. coli
staph aureus
strep pyogenes
p. aeruginosa
steps for immune response against extracellular bacteria
- phagocytosis of extracellular bacteria (neutrophils and macrophages)
- recognition of microbe by phagocyte
- engulfment and formation of phagosome
- lysosome fusion and phagolysosome formation
- killing of microbes by lysosomal enzymes in phagolysosomes
binds mannose on microbial cell wall mediating cell-microbe binding and initiating phagocytosis
mannose receptor
Binds microbes opsonized with complement proteins
mac-1 integrin
binds microbes in a non-mannose specific manner
scavenger receptor
opsonization of a microbe occurs when it is coated/bound by an opsonin to target it for _____
phagocytosis (mediates binding to phagocyte receptors)
activated macrophages and neutrophils convert molecular oxygen to ROS (reactive oxygen species). This process is called _____
respiratory burst
macrophage role in immunity against extracellular microbes
- remove antigen by phagocytosis
- process and present antigen to T cells
- secrete pro-inflammatory cytokines and chemokines
role of neutrophils in immunity against extracellular microbes
- migrate toward inflammation site in response to chemotactic factors (IL-8, IFN-gamma, C5a)
- effectively phagocytose microbes or kill by oxygen independent mechanism
oxygen independent mechanism of neutrophils
degranulation (release of granuoles)
Role of COMPLEMENT in Immunity against Extracellular Microbes
- serves as opsonin, enhances phagocytosis by phagocytes
- serves as chemokine, recruits and activates leukocytes to site of inflammation
- forms membrane attack complex (MAC) and mediates lysis of microbe
B cell role in immunity against extracellular microbes
neutralization of microbes and microbial toxins by antibodies (has other roles too)
Which Th response is more important during extracellular defense?
Th2
T cell role in immunity against extracellular microbes
- make inflammatory cytokines which activate macrophages to promote phagocytosis, bacterial killing, and inflammation
- produce cytokines which are B cell growth factors which activate B cells and promote antibody production
CD4+ T cells are called ____ when they make inflammatory cytokines and ____ when they make B cell promoting cytokines
Th1 cells ; Th2 cells
examples of intracellular pathogens
mycobacteria
listeria monocytogenes
salmonella species
can survive inside host cells to evade the immune system
facultative intracellular pathogens
MUST INFECT HOST to survive
obligate intracellular pathogen
what immune responses are involved in immunity to intracellular pathogens?
both innate and adaptive
____ immune response is dominant rather than antibody response
cell mediated immune response
Disease and resulting pathology from immunity to intracellular pathogens are a consequence of:
the host’s immune response to the infectious agent
innate immune system cells in response to intracellular pathogens
dendritic cells
NK cells
macrophages/neutrophils
adaptive immune cells in response to intracellular pathogens
CD4+ T cells (helper T cells)
CD8+ T cells (cytotoxic T cells)
dendritic cells carry antigen from site of infection to ____ where they will present antigen to naive T cells
lymph node
NK cell role against intracellular microbes
main function is to kill virus infected cells and tumor cells
how do T cells recognize infected cells?
Class I MHC-expressing cell and integrins
CD4+ T cells recognize antigen in ____ restricted manner; they then differentiate into ____ subsets producing distinct cytokines with distinct biological activity
MHC II; Th1 and Th2
Th1 CD4+ T cells produce IFN-γ and TNF-α and promote:
cell mediated immunity
Th2 CD4+ T cells produce IL-4 and promote:
antibody mediated immunity
Which Th cell would be needed against intracellular infections?
Th1
CD8+ T cells recognize antigen in a ____ restricted manner
MHC I
CD8+ T cells are _____ as they secrete perforin and granzymes which will directly lyse/kill infected cells; they are very important for _____ immunity
cytotoxic T cells; antiviral
