Adptive &Innate Immunity

Natural & Adaptive Immune Mechanishmes
Dr.Baha,Hamdi.AI-amiedi
The main function of the immune system is to prevent or
limit infections by pathogenic microorganisms, such as bacteria,viruses,parasites, and fungi. The recognition of microorganisms and foreign
substances is the first event in immune responses.
of a host The body’s defense mechanisms can be divided into:
(a) innate(natural) immunity
(b) acquired (adaptive) immunity Factors influencing innate immunity 1-Age 2-Nutrition status 3-Hormonal level
The factors that may influence innate immunity of the host include age and nutritional status of the host.
1-Age: Extremes of age make an individual highly susceptible to various infections. This is explained
in part by the immature immune system in very young children and waning immunity in older individuals. The fetus-in-utero is usually protected
from maternal infections by the placental barrier
2-Nutritional status: Nutritional status of the host plays an important role in innate immunity. Both humoral and cell mediated immunities are lowered in mal nutrition. Examples are:
? Neutrophil activity is reduced, interferon response is
decreased, and C3 and factor B of the complement are
decreased in protein–calorie malnutrition.
? Deficiency of vitamin A, vitamin C, and folic acid makes an individual highly susceptible to infection by many microbial