Factors influencing innate immunity

Factors influencing innate immunity

The factors that may influence innate immunity of the host include age and nutritional status of the host.

Age: Extremes of age make an individual highly susceptible tovarious 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. However, human immunodeficiency virus (HIV), rubella virus, cytomeg-alovirus, and Toxoplasma gondii cross the placental barrier and cause congenital infections.

Very old people are susceptible to suffer more than young people from a disease (e.g., pneumonia) and have high mortal-ity. Measles, mumps, poliomyelitis, and chicken pox are few examples of the diseases that cause more severe clinical illness in adults than in young children. This may be due to more active immune response in an adult causing greater tissue damage.

Nutritional status: Nutritional status of the host plays animportant role in innate immunity. Both humoral and cell-mediated immunities are lowered in malnutrition. 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 pathogens.

Hormonal levels: Individuals with certain hormonal disordersbecome increasingly susceptible to infection. For example, indi-viduals suffering from diabetes mellitus, hypothyroidism, and adrenal dysfunction are increasingly susceptible to staphylococ-cal infection, streptococcal infection, candidiasis, aspergillosis, zygomycosis and many other microbial infections. Similarly, pregnant women are more susceptible to many infections due to higher level of steroid during pregnancy.