Updated project metadata. Alzheimer’s disease (AD) is the most prevalent neurodegenerative disease in the elderly, characterized by the accumulation in the brain of misfolded proteins, inflammation, and oxidative damage leading to neuronal cell death. The necessity of searching for new non-invasive biomarkers in tissues or body fluids easy and painless to collect has been evidenced. In this context, saliva has been chosen to investigate new possible biomarkers using a proteomics-based approach. Previous results obtained on the acid-soluble fraction of saliva from AD patients by a Top-Down proteomic approach revealed the potential role of cystatin B in the disease, a protein capable of interacting with other proteins, including amyloid beta, and to homo-polymerize. Thus, the first aim of the present project has been to demonstrate the existence of a multiprotein complex with cystatin B in whole saliva samples and to characterize it, secondly, we further studied the cystatin B interactome to individuate any qualitative-quantitative difference between AD patients and healthy subjects age and sex matched. To these aims, we performed some preliminary tests mainly by western blot to look for high molecular weight positive signals related to cystatin B in saliva, and, then, in order to characterize the presence of potential multiprotein complexes, we performed Co-IP assays followed by in gel tryptic digestion and RP-nanoHPLC-HR-ESI-MS/MS analysis (reverse-phase nano-high-performance liquid chromatography separation coupled to electrospray-ion trap tandem mass spectrometry).