Respiratory infections: Role of Vitamin D and surfactant proteins A and D.

Respiratory tract infection is the common viral infection and the principal cause of death among children under 5 years of age. It damages lung epithelium and increases mucus production and inflammation, leading to dyspnea. The sunshine vitamin (Vitamin D) and surfactant protein (SP) A and D along with their usual function play an important role in host defense. This article reviews with immune role of Vitamin D and SP A and D which aids excessive cytokines production, boosts phagocytosis, hinders inflammatory activity, and thus acts as a first-line defense against lung pathogens.