Distinct mechanisms of the newborn innate immunity

•Newborn immune-protection depends mainly on passive transfer of Immunoglobulin G from mother.•The innate and adaptive immunity in newborns is relatively naïve.•The immune responses in newborns can be improved using additional co-stimulatory agents.•Newborns are biased against the production of pro-inflammatory cytokines.•Understanding the immunological mechanisms in a newborn could help improve protection against infections.

The ontogeny of immunity during early life is of high importance as it shapes the immune system for the entire course of life. The microbiome and the environment contribute to the development of immunity in newborns. As immune responses in newborns are predominantly less experienced they are increasingly susceptible to infections. Though the immune cells in newborns are in ‘naïve’ state, they have been shown to mount adult-like responses in several circumstances. The innate immunity plays a vital role in providing protection during the neonatal period. Various stimulants have been shown to enhance the potential and functioning of the innate immune cells in newborns. They are biased against the production of pro-inflammatory cytokines and this makes them susceptible to wide variety of intracellular pathogens. The adaptive immunity requires prior antigenic experience which is very limited in newborns. This review discusses in detail the characteristics of innate immunity in newborns and the underlying developmental and functional mechanisms involved in the immune response. A better understanding of the immunological milieu in newborns could help the medical fraternity to find novel methods for prevention and treatment of infection in newborns.