The production of antibodies in new born is undeveloped; they are more prone towards infections and allergies. Environmental factors and hereditary history plays a vital role. The importance of vitamins and minerals in the mother’s diet will have a subsequent impact on the infant’s health. However, a new born acquires immunity from his/her mother against a few diseases like chicken pox and measles by birth. Breast feeding seemingly decreases the risk of allergic disorders and even reduces the rate of infant mortality. Prebiotics (non-digestible food ingredients) stimulate growth and improve antibody response to vaccination, while probiotics are effective in preventing antibiotic associated diarrhoea.
Immunity is a state of having sufficient biological defences to avoid infection, disease or other unwanted biological invasion. It’s a capability of body to resist harmful microbes from entering it. Immunity is of 2 types, innate (nonspecific) immunity and Acquired immunity. Innate (nonspecific) immunity is the natural resistance with which a person is born. It is provided by skin, respiratory and gastro-intestinal epithelia and other mucosa; it comprises of humeral factors such as cytokines and complement components. Acquired immunity is the immunity induced in the host itself after exposure to an antigen, which is active immunity, for example, after infection with measles, a child becomes immune it measles. Second type of acquired immunity, passive immunity is one which is passively transferred from an immune host for example, with immunoglobulin infusion for rabies or chicken pox.
The development of immune system occurs in an infant after birth, children emerge from sterile environment of uterus into a world teeming with bacteria. Within first day of life, the mucosal surfaces of Gl and respiratory tract are colonized with bacterial communities. Moreover, at birth, the lymphoid system is not yet mature. All T and B lymphocytes are naive, i.e., they have not yet encountered antigen. Therefore, the memory T and B lymphocytes have not yet developed. The neonate is able to mount an antibody response on encountering a primary infection. Neonates are however, unable to respond to polysaccharide antigens, making them vulnerable to infections with group B streptococci and pneumococci. Development of intestinal microflora also occurs after birth. At birth, the intestine of a neonate is sterile, but becomes rapidly colonized thereafter. Neonatal intestine contains large number of facultative anaerobes such as Streptococcus and coliforms. These decline in number during weaning as obligate anaerobes such as Bacteroides and Clostridium establish a foothold and eventually become predominant community residing in gut.
Neonatal immunity plays an important role in non-infectious conditions like Allergy. Immune system is tightly controlled by its own regulatory network to prevent inappropriate immune responses. Failure of this regulatory system results in development of allergy or autoimmunity. Presence of family history and environmental factors (feeding and nutritional composition) play important roles in development of allergic disease in children. Advantages of breast milk are due to bolstering up of host defines in infants due to presence of secretory IgA, which is directed specifically against enteric and respiratory pathogens from environment. Lactoferrin, a ferric iron-binding glycoprotein, inhibits growth of pathogens by competing with bacteria for ferric iron. Lactoferricin, a chelation-independent bactericidal activity Lysozyme, antimicrobial peptide cleaves peptidoglycans in cell walls of bacteria.