Updated project metadata. In the HPLC high-resolution ESI-MS profiles of both multiple sclerosis subjects and healthy controls saliva samples three proteins, with exp. monoisotopic ion [M+H]+ at 13493.9 ± 0.2 m/z, 13696.9 ± 0.2 m/z (+203 Da, with respect to 13493.9), and 13843.1 ± 0.2 m/z (+147 Da, with respect to 13696.9) eluting between 37.8-38.2 minutes, were detected. The mass difference of 203 Da suggested that the protein with exp. monoisotopic [M+H]+ at 13696.9 ± 0.2 m/z could correspond to the N-acetylhexosamine (theor. monoisotopic ion at 203.1 m/z) derivative of the 13493.9 ± 0.2 m/z protein. On the other hand, the mass difference of 146 Da between the proteins with exp. monoisotopic [M+H]+ at 13843.1 ± 0.2 m/z and 13696.9 ± 0.2 m/z was in agreement with an additional deoxyhesose moiety (theor. monoisotopic ion at 146.1 m/z). Manual inspection of the high-resolution MS/MS spectra of the [M+10H]+10 ions at 1351.00, 1371.32 and 1386.11 m/z allowed to establish that the three proteins were different proteoforms of PIP with the N-terminal glutamine residue converted to pyro-glutamic acid and with two disulfide bonds, but not to assign the glycosylation site. The presence in the MS/MS spectra of low-molecular weight saccharide oxoniun ions at 204.087 and 138.106 m/z confirmed the presence of an N-acetylhexosamine moiety in the protein with [M+H]+ at 13696.9 ± 0.2 m/z.