Immunological memory Flashcards
phases from entry of microorganism to clearance of pathogen
- establishment of infection
- inductive phase
- effector phase
- memory phase
*duration of infection is from phases 1 to 3
stages of a response to an infection
penetration of epithelium
local infection of tissues
lymphatic spread
adaptive immunity
response to infection mechanism: penetration of epithelium
wound healing induced antimicrobial peptides, phagocytes and complement destroy invading microorganisms
response to infection mechanism: local infection of tissues
complement activation
dendritic cells migrate to lymph nodes
phagocyte action
NK cells activated
cytokines and chemokines produced
response to infection mechanism: lymphatic spread
pathogens trapped and phagocytosed in lymphoid tissue
adaptive immunity initiated by migrating dendritic cells
response to infection mechanism: adaptive immunity
infection cleared by specific antibody
T-cell dependent macrophage activation and cytotoxic T cells
types of ILC’s and the type of pathogen they respond to
cytotoxic ILC (NK): viruses
group 1 ILC: intracellular bacteria
group 2 ILC: helminths (parasites)
group 3 ILC: extracellular bacteria
types of ILC’s and the innate sensor cell that releases cytokines and chemokines to activate each of them
cytotoxic ILC (NK): DCs
group 1 ILC: macrophages
group 2 ILC: Tuft cells
group 3 ILC: macrophages and DCs
cytokines and chemokines produced by innate sensor cells activate…
Innate lymphoid cells
types of innate sensor cells
dendritic cells
macrophages
tuft cells
what makes up immune effector modules
integration of ILC’s, T-cell subsets and innate effector cells
what is the role of T-helper 1 cells
coordinate and amplify host response to intracellular pathogens through classical activation of macrophages
what is the role of T-helper 2 cells
coordinate type 2 responses to expel intestinal helminths and repair tissue injury
what Is the role of T-helper 17 cells
coordinate type 3 responses to enhance the clearance of extracellular bacteria and fungi
IL17 and IL22 induce the production of AMPs by epithelial cells
what processes are included in the primary immune response
T and B cell activation
differentiation
proliferation
properties of the primary immune response
type of B cell: naive
lag time: 4-7 days
time of peak response: 7-10 days
magnitude of peak response: antigen-dependent
isotype: IgM
antibody affinity: low
properties of the secondary immune response
type of B cell: memory
lag time: 1-3 days
time of peak response: 3-5 days
magnitude of peak response: 1000x higher than primary
isotype: IgG
antibody affinity: high
immunological memory is long-lived after…
infection or vaccination
what are the 2 general models for memory T cell development
- linear model: memory T cells arise from effector T cells as the primary immune response subsides
- branching model: an activated naive T cell gives rise to daughter cells that commit to either effector OR memory cell program
what are the types of memory T cells
central memory (Tcm)
effector memory (Tem)
tissue-resident subsets (Trm)
Protein = CCR7
what T cells is it present in and what are its functions
naive T cell, central mem. T cell
chemokine receptor for getting into the lymph node
protein = CD45RA (or CD45R0)
what T cells is it present in and what are its functions
all naive, effector and memory T cells
modulates T cell receptor signalling
protein = Bcl-2
what T cells is it present in and what are its functions
naive, all memory T cells and some effector T cells
prevents intrinsic apoptosis, promotes cell survival
what alters when naive T cells become memory T cells
the expression of certain proteins
where do each type of memory T cell reside within our tissues
central memory T cell: recirculate between blood, T cell zones of SLO and lymph
effector memory T cells: recirculate between non-lymphoid tissues lymph, lymph nodes, and blood. some remain in circulation and migrate only though spleen
resident memory T cells: do not recirculate, confined to a single tissue
circulating memory T cells acquire heightened sensitivity to which cytokines
IL7 and IL15
how do memory T cells survive long-term
they undergo metabolic reprogramming
what are the requirements for naive T cell survival
require signals from contact with self peptide:MHC complexes and the cytokine IL-7
what are the requirements for memory T cell survival
need contact with cognate peptide:MHC complexes but reduced co-stimulation to undergo clonal expansion
related to antibodies, what increases with repeated immunization
the affinity and amount of antibody
what happens to lymphocytes with repeated immunization
- memory B cells can re-enter germinal centres and undergo additional somatic hypermutation and affinity maturation during secondary immune responses
- in immune individuals, secondary subsequent responses are mainly attributable to memory lymphocytes
what is Fcy-RIIB1
- an inhibitory receptor on the surface of naive B cells - blocks their activation in secondary response
- interacts with Fc component of IgG
what is RHoGAM
an anti-Rh Ig
it binds to the FcyRIIB1 inhibitory receptor on naive B cells that recognize Rh
what is the original antigenic sin
- individuals who have been infected with one variant of a virus are infected with a different variant, they make antibodies only agains epitopes that are present on the initial virus
- benefits host through rapid response
- pattern breaks only when exposure to completely novel virus variants lacking original epitopes
