L1.13: Immunology: Different forms of pathogens and immunological response
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Today, more than ever, we
Today, more than ever, we are beginning to understand on a molecular and cellular level how a vaccine or infection leads to the development of immunity.
Historical studies revealed a complex system of cells and soluble compounds that have evolved to protect us against an enormous range of invaders of all shapes, sizes, and chemical structures.
Organisms causing disease are termed pathogens, and the process by which they induce illness in the host is called pathogenesis.
Human pathogens can be grouped into four major categories based on shared characteristics: viruses, fungi, parasites, and bacteria.
Some of the shared characteristics that are common to groups of pathogens, but not to the host, can be exploited by the immune system for recognition and destruction.
The microenvironment in which the immune response begins to emerge can also influence the outcome; the same pathogen may be treated differently depending on the context in which it is encountered.
Some areas of the body, such as the CNS, are virtually “off limits” for the immune system because the immune response could do more damage than the pathogen.
In other cases, the environment may come with inherent directional cues for immune cells. For instance, some foreign compounds that enter via the digestive tract, including the commensal microbes that help us digest food, are tolerated by the immune system.
However, when these same foreigners enter the bloodstream they are typically treated much more aggressively.
Each encounter with a pathogen thus engages a distinct set of strategies that depends on the nature of the invader and the microenvironment in which engagement occurs
The immune pathways do not become engaged until foreign organisms first breach the physical barriers of the body.
The skin and the mucous membranes
The acidity of the stomach contents, of the vagina, and of perspiration poses a barrier to many organisms, which are unable to grow in low pH
The importance of barriers becomes obvious when they are surmounted
Animal bites can communicate rabies or tetanus
Insects puncture wounds can transmit the causative agents of such diseases as malaria (mosquitoes), plague (fleas), and Lyme disease (ticks).
A dramatic example is seen in burn victims, who lose the protective skin at the burn site and must be treated aggressively with drugs to prevent the rampant bacterial and fungal infections that often follow.
The process of pathogen recognition involves an interaction between the foreign organism and a recognition molecule (or molecules) expressed by host cells.
Historical studies revealed a complex system of cells and soluble compounds that have evolved to protect us against an enormous range of invaders of all shapes, sizes, and chemical structures.
Organisms causing disease are termed pathogens, and the process by which they induce illness in the host is called pathogenesis.
Human pathogens can be grouped into four major categories based on shared characteristics: viruses, fungi, parasites, and bacteria.
Some of the shared characteristics that are common to groups of pathogens, but not to the host, can be exploited by the immune system for recognition and destruction.
The microenvironment in which the immune response begins to emerge can also influence the outcome; the same pathogen may be treated differently depending on the context in which it is encountered.
Some areas of the body, such as the CNS, are virtually “off limits” for the immune system because the immune response could do more damage than the pathogen.
In other cases, the environment may come with inherent directional cues for immune cells. For instance, some foreign compounds that enter via the digestive tract, including the commensal microbes that help us digest food, are tolerated by the immune system.
However, when these same foreigners enter the bloodstream they are typically treated much more aggressively.
Each encounter with a pathogen thus engages a distinct set of strategies that depends on the nature of the invader and the microenvironment in which engagement occurs
The immune pathways do not become engaged until foreign organisms first breach the physical barriers of the body.
The skin and the mucous membranes
The acidity of the stomach contents, of the vagina, and of perspiration poses a barrier to many organisms, which are unable to grow in low pH
The importance of barriers becomes obvious when they are surmounted
Animal bites can communicate rabies or tetanus
Insects puncture wounds can transmit the causative agents of such diseases as malaria (mosquitoes), plague (fleas), and Lyme disease (ticks).
A dramatic example is seen in burn victims, who lose the protective skin at the burn site and must be treated aggressively with drugs to prevent the rampant bacterial and fungal infections that often follow.
The process of pathogen recognition involves an interaction between the foreign organism and a recognition molecule (or molecules) expressed by host cells.
12 ماه پیش
در تاریخ 1402/05/03 منتشر شده
است.
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