BPIFB1, also known as LPLUNC1, belongs to the BPI/LBP/Plunc superfamily, plunc family. BPIFB1 may be involved in the innate immune response to bacterial exposure in the mouth, nasal cavities, and lungs. BPIFB1 is expressed in the upper respiratory tract and oral cavity, which may function in host defence. The expression of BPIF proteins is associated with CF lung disease in humans and mice. It is unclear if this elevation of protein production, which results from phenotypic alteration of the cells within the diseased epithelium, plays a role in the pathogenesis of the disease. BPIFB1 is an abundant, secreted product of goblet cells and minor mucosal glands of the respiratory tract and oral cavity and suggest that the protein functions in the complex milieu that protects the mucosal surfaces in these locations.