Immunology Flashcards
Innate immunity
cellular and biochemical defense mechanism that are in place before infection and are poised to respond rapidly to infection
Principal Components of the Innate Immunity
1) physical and chemical barriers, such as epithelia and antimicrobial
chemicals produced at epithelial surfaces;
(2) phagocytic cells (neutrophils, macrophages), dendritic cells, and natural
killer (NK) cells and other innate lymphoid cells; and
(3) blood proteins, including members of the complement system and other
mediators of inflammation.
Functions of innate immunity
-is the initial response to microbes that prevents, controls, or eliminates
infection of the host by many pathogens
* Eliminates damaged cells and initiate the process of tissue repair. It uses
mechanisms that recognize and respond to host molecules produced by,
released from, or accumulate in stressed, damaged, and dead host cells.
* Innate immunity stimulates adaptive immune responses and can influence the
nature of the adaptive responses to make them optimally effective against
different types of microbes.
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PAMPs
-microbial substances that stimulate innate system
-Ex: dsRNA, ssRNA, pilens, LPS, etc.
Toll-like receptors (TLRs)
-are an evolutionarily conserved family of pattern
recognition receptors expressed on many cell types that recognize products of a
wide variety of microbes as well as molecules expressed or released by stressed
and dying cells.
What recognizes PAMPs?
a series of receptors expressed by phagocytes usually(macrophages and neutrophils), dendritic cells, epithelial cells that form
the barrier interface between the body and the external environment, and many
other types of cells that occupy tissues and organs.
Adaptive immunity
Immune defenses that are stimulated by exposure to infectious agents and increase in magnitude and defensive capabilities with each exposure
Defining characteristics of adaptive immunity are
-the ability to distinguish different substances called specificity
- the ability to respond more vigorously to repeated exposures to the same microbe, known as memory
Two components of adaptive immunity
-humoral response mediated by antibodies produced by B lymphocytes.
Antibodies recognize, neutralize and target microbes for elimination by
various effector mechanisms. Antibodies themselves are specialized and may
activate different mechanisms to combat microbes (effector mechanisms).
-Cellular responses: mediated by T lymphocytes. Defense against
intracellular pathogens is a function of cell-mediated immunity, which
promotes the destruction of microbes residing in phagocytes or the killing of
infected cells to eliminate reservoirs of infection.
B lymphocytes
Block infections and eliminate extracellular microbes
Helper T lymphocyte
activate macrophages to kill phagocytosed microbes
-inflammation
Cytotoxic T lymphocytes
Kill infected cells and eliminate reservoirs of infection
Regulatory T lymphocytes
suppression of other lymphocytes
Does innate or adaptive immunity have non reactivity to self?
Both
Minutes-Hours innate immunity response
-recognition of leukocytes
-non specific phagocytosis(macrophages and neutrophils)
-cytokine release
-release of toxic chemicals
-complement activation
