outcome of immune system recognition Flashcards
what is the take home message in cytokines influencing cell polarization?
cytokines modulate cell polarization, such that polarized cells (such as macrophages or T cells) express different genes and markers and their immunological functions vary accordingly
what immune response system are PRRs a part of?
the innate immune system
what are routes pathogens can enter the body through?
respiratory tract, mucosal surfaces, skin (wounds, insect bites)
how is the immune system able to recognize and respond appropriately?
PAMPs are recognized by specific PRRs, pathogens from different categories express different PAMPs as well as different toxins/virulence factors.
what are cellular responses in response to PAMPs binding to PRRs?
activation of cell signalling pathways, gene transcription and expression of new protein repertoires, activation of antimicrobial functions, and production of cytokines and chemokines (initial phase of the immune response: recognition/sensing of a pathogen)
what is an example of an immune recognition?
macrophage containing TLR4 PRR, which recognizes the PAMP LPS from gram-negative bacteria. the binding of this specifc PAMP to the specific PRR activates different cell signaling pathways
what does the sensor cell need to do, in order to mount an efficient immune response?
needs to communicate with other cells like cytokines, to modify phenotype and activity, as well as chemokines, to influence cellular migration and homing
how to chemokines participate in cell-to-cell communication?
they reach the site of infection where they recruit additional immune cell types, and home towards secondary lymphoid organs
what do recruited cells have to have in order to receive a cell signal?
must express the chemokine-specific receptor
what are the cascading effects of activated cells after recognizing their ligands?
inflammation, increased vasodilation, increased cell infiltration and capillary leakage, and heat/fever - leads to the 4 cardinal signs of inflammation
what does the activation of innate immune cells cause?
increased phagocytosis, phagolysosomal digestion of intracellular pathogens, oxidative burst, antigen processing and presentation, production of cytokines, etc.
what is the immunological synapse between the innate and adaptive immune response?
antigen presentation between an APC and a naive T-cell
what is the definition of an antigen?
any substance that binds specifically to an antibody or a T cell receptor
what are antigenic peptides bound to on an APC?
onto the major histocompatibility complex, which then form complexes and are presented to T cells harboring a specific TCR, and alone with co-stimulatory molecules, leading to T cell activation
what are the stages of antigen presentation?
- PAMP recognition through PRR
- DC activation and maturation
- antigen processing and co-stimulatory molecule expression
- migration to lymph node
- antigen presentation and activation of T cells
activated APCs can also produce cytokines which affects the type of T cell response, which is influenced by the nature of PAMPs/PRRs and cellular environment
what is T cell differentiation influenced by?
cytokines produced by APCs
what does T cell activation through antigen presentation cause?
cell division and expansion of T cells, eventually leading to contraction and memory
what happens when B cells are activated?
activated with the help of T cells, to become either plasma or memory B cells
what are the steps/signals of T cell and B cell division and expansion?
signal 1: antigen presentation
signal 2: co-stimulatory molecules
signal 3: cytokines
cell division and expansion
contraction and memory
what immune cells do B cells interact with before division and expansion?
follicular dendritic cells, then becoming primed B cells
what do B cells do once they are primed?
present antigens to T cells in the border zone. this causes T cells to activate B cells which leads to their proliferation
what occurs after B cell proliferation?
they differentiate into different types of B cells
