IgG1 glycosylation profiles of a pregnant woman with anti-D. Tryptic IgG1 Fc glycopeptides of total IgG1 (A) and anti-D specific IgG1 (B), affinity-purified from the serum of a pregnant woman, were measured by positive-ion reflectron mode matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The profile shown represents specific antibodies with a low fucosylation of 16%, while the total IgG1 was highly fucosylated (94%). For the assignment and the definitions of the glycopeptides signals see Fig 1 . Pep, peptide moiety; *, contaminant.