The prolactin-inducible-protein (PIP): A regulatory molecule in adaptive and innate immunity

摘要

The Prolactin-inducible-protein (PIP)/Gross Cystic Disease Fluid Protein-15 (GCDFP-15) gene is highly expressed in salivary, lacrimal and sweat glands and the protein abundantly found in the secretions that originate from these glands;saliva, tears and sweat. PIP is thus considered to be strategically located at sites viewed as the first port of entry for invading organisms. PIP is also found over-expressed under abnormal and pathological conditions of the breast and prostate. The function of PIP has yet to be defined but it has been implicated to play a role in immunity, with respect to bacterial and viral infection, cancer and fertility. Despite such predictive functions, there is still no clear demonstration of an immunoregulatory role for PIP. In this review we will focus on accumulating evidence that suggests a role for PIP in both innate and adaptive immunity. Moreover, we will discuss recent evidence that defines a modulatory role for PIP with regards to a CD4+ T cell immune response, identifying for the first time, a critical role for PIP in effective cell-mediated immunity against an intracellular pathogen.