15免疫缺陷eng v.ppt

15 免疫缺陷immunodeficiency
The immune system is work of interacting cellular and ponents. Its function is to distinguish entities within the body as "self" or "nonself" and to eliminate those that are nonself.
anisms are the principal nonself entities, but neoplasms, transplants, and certain foreign substances (eg, some toxins) are also important. To plish its tasks, the immune system has evolved two mechanisms: nonspecific immunity and specific immunity, which are linked to and influence each other.
Nonspecific (Innate) Immunity
This type of immunity is older ically, is present at birth, does not require a previous encounter with the offending substance, and does not develop memory. Innate immunity includes barriers, such as the skin, and chemical protection, such as gastric acid.
There are two ponents:
the phagocytic system, whose function is to ingest and digest invading anisms, and
(2) natural killer (NK) cells, whose function is to kill some tumors, anisms, and virally infected cells. The ponents consist plement proteins, acute phase reactants, and cytokines.
Specific (Adaptive) Immunity
Specific immunity has the hallmarks of learning, adaptability, and memory. The ponent is the lymphocyte, and immunoglobulins (Igs) are the ponent.
Immunodeficiency diseases: A group of diverse conditions caused by one or more immune system defects and characterized clinically by increased susceptibility to infections with consequent severe, acute, recurrent, or chronic disease.
An immunodeficiency disorder should be considered in anyone with infections that are unusually frequent, severe, and resistant; without a symptom-free interval; from an anism; or with unexpected or plications.
Since immunodeficiency disorders are relatively mon, other disorders leading to recurrent infection should be considered first. If these disorders can be excluded, a defect in host defense should be suspected.
DISORDERS WITH INCREASED SUSCEPTIBILITY TO UNUSUAL INFECTIONS