The new process gives pure and stable IgG solution with an average yield of 4.8 g of IgG per kg of recovered plasma and has a very high capacity to remove even physico-chemically resistant viruses.

No abstract

We have previously isolated and partially characterised the components of a highly purified interferon-A (IFN-A) preparation produced by Sendai-virus-induced human peripheral blood leukocytes. Nine IFN-A species were identified, and two of these were found to be glycosylated [Nyman, T. A., Tölö, H., Parkkinen, J. & Kalkkinen, N. (1998) Identification of nine interferon-A subtypes produced by Sendaivirus-induced human peripheral blood leukocytes, Biochem. J. 329, 295Ϫ302]. Here, we isolated the Nlinked oligosaccharides of IFN-A14c and the O-linked chains of IFN-A2b, and the glycans were characterised by electrospray tandem mass spectrometry and by specific glycosidase digestions monitored by matrix-assisted laser desorption ionisation time of flight mass spectrometry. The IFN-A14c N-glycans were shown to exhibit core-fucosylated biantennary glycans, with about 10% carrying an additional A1,3-linked fucose unit at the antennae. The IFN-A2b was shown to carry about 50% core type-1 disialyltetrasaccharides, 30% core type-1 monosialyltrisaccharides and 20% core type-2 monosialylpentasaccharides.Keywords : interferon-A; glycosylation; matrix-assisted-laser-desorption ionisation time of flight; electrospray-ionisation collision-induced dissociation; glycosidase. The oligosaccharide structures in a glycoprotein can have profound effects on its biological properties [12]. However, the the mRNA level in leukocytes induced by Sendai virus [2], and it has previously been shown [3] that at least nine different sub-structural characterisation of glycoprotein glycans has been hampered by the microheterogeneity usually present in a given types are also produced at the protein level. The biological significance of the expression of several closely similar IFN-A pro-glycosylation site, and by the lack of efficient chromatographic means to isolate pure oligosaccharide species for enzymatic and teins is not known, but several reports suggest that they have quantitatively distinct patterns of antiviral, growth inhibitory and spectrometric analyses. Mass spectrometry has been widely used for structural analyses of glycoprotein glycans. Extensive studies killer-cell-stimulatory activities [4Ϫ9]. Two IFN-A variants, IFN-A2a and IFN-A2b, are mass produced in Escherichia coli by of oligosaccharides with fast-atom bombardment and liquid-secondary-ion mass spectrometry provided the basis of the straterecombinant technology and marketed as drugs. Unlike natural IFN-A, these recombinant IFN-A products have proved immuno-gies for obtaining sequence and linkage information [13Ϫ16], and more recently, matrix-assisted laser desorption/ionisation genic in some patients [10, 11], which could be due to unnatural (MALDI) and electrospray ionisation (ESI) mass spectrometry forms of IFN-A proteins. Therefore, it may be important for the have been successfully employed in glycan analyses [17Ϫ19]. development of IFN-A drugs to not only identify the IFN-A subBy complementing MS analyses with specific glycosidase treattypes and variants expressed in no...

The human interferon-alpha (IFN-alpha) family is encoded by 13 different functional genes, and including all cloned sequence variants there are 28 potential IFN-alpha proteins. To find out which of the described sequences are expressed in normal human leucocytes, we have isolated and partly characterized the components of a highly purified IFN-alpha preparation produced by Sendai virus-induced human peripheral blood leucocytes. The identification protocol consisted of N-terminal sequencing and mass mapping of the proteins separated by reverse-phase HPLC and/or SDS/PAGE. The highly purified leucocyte IFN-alpha preparation was found to contain at least nine different IFN-alpha species: IFN-alpha1a, IFN-alpha2b, IFN-alpha4b, IFN-alpha7a, IFN-alpha8b, IFN-alpha10a, IFN-alpha14c, IFN-alpha17b and IFN-alpha21b. IFN-alpha1a was the major subtype, comprising approx. 30% of total leucocyte IFN-alpha. IFN-alpha14c, the only subtype containing potential N-glycosylation sites, was shown to be glycosylated at Asn-72. Molecular mass determination of the intact proteins by electrospray ionization MS showed that there are no other post-translational modifications in the IFN-alpha subtypes than the glycosylation of IFN-alpha2b and IFN-alpha14c. Only one sequence variant was found for each subtype, suggesting that the other described gene sequences represent allelic variants or mutations that are more rarely found in the general population.