An antibody preparation suitable for intravenous administration in humans includes IgG, IgA and at least 5% IgM antibodies by weight of the total amount of antibodies. The preparation is prepared from human plasma, has specific complement activating activity, and, in an in vitro assay with human serum suitable to determine the ability of the antibody preparation to activate complement unspecifically, the antibody preparation generates substantially no C5a and/or substantially no C3a. The antibody preparation can have medical uses.

An Fc-binding polypeptide of improved alkali stability, comprising a mutant of an Fc-binding domain of Staphylococcus Protein A (SpA), as defined by SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO:3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:22, SEQ ID NO 51 or SEQ ID NO 52 wherein at least the asparagine or serine residue at the position corresponding to position 11 in SEQ ID NO:4-7 has been mutated to an amino acid selected from the group consisting of glutamic acid, lysine, tyrosine, threonine, phenylalanine, leucine, isoleucine, tryptophan, methionine, valine, alanine, histidine and arginine.

The present invention is directed to a method of inactivating virus that is present during production of a polypeptide of interest. In particular, the present invention is directed to a method of on-column virus inactivation using a low pH and high salt wash solution that effectively inactivates viruses with minimum recovery loss of the polypeptide.

A specific antibody for detecting the blood brain barrier early injury of cerebral ischemic stroke is characterized by specifically identifying KTRRKMDRYDKSNIL in degradation fragments of an occludin protein, but not identifying the full-length occludin protein. Therefore, the antibody can be used for specifically detecting the blood brain barrier early injury of the cerebral ischemic stroke, and can eliminate the influence of the full-length occludin protein in serum on a detection result, so that the specificity and accuracy of detecting the blood brain barrier early injury of the cerebral ischemic stroke are obviously improved.

The present invention relates to a signal peptide for reducing the end heterogeneity of a heterologous polypeptide. Specifically, the present invention relates to a signal peptide for protein expression. The present invention further relates to a recombinant polypeptide, a preparation method therefor, and a composition containing a recombinant polypeptide.

Antibodies that specifically bind PD-1 or antigen binding fragments thereof, polynucleotides encoding the antibodies or fragments, and methods of making and using the foregoing are useful in the treatment of an inflammatory or immune disorder.

The present invention provide novel immunofiber compositions for protein or peptide purification and simple and cost-efficient methods and systems using these compositions. In some embodiments, the immunofibers comprise a customized Z-33 peptide derived from Staphylococcus aureus Protein A which is used to construct immuno-amphiphile molecules that assemble into immunofibers in aqueous solution with bioactive epitopes on the surface and have peptide or protein binding ability.

The invention relates to a separation matrix comprising at least 11 mg/ml Fc-binding ligands covalently coupled to a porous support, wherein: a) the ligands comprise multimers of alkali-stabilized Protein A domains, and b) the porous support comprises cross-linked polymer particles having a volume-weighted median diameter (d50,v) of 56-70 micrometers and a dry solids weight of 55-80 mg/ml.

The present invention concerns a method of cleaning and/or sanitizing a separation matrix comprising multimers of immunoglobulin-binding alkali-stabilized Protein A domains covalently coupled to a porous support. The method comprises the steps of: a) optionally purifying a mixture comprising a first immunoglobulin using the separation matrix; b) providing a cleaning liquid comprising at least 50% by volume of an aqueous alkali metal hydroxide solution; and c) cleaning and/or sanitizing the separation matrix by contacting the cleaning liquid with the separation matrix for a predetermined contact time. The alkali-stabilized Protein A domains comprise mutants of a parental Fc-binding domain of Staphylococcus Protein A (SpA), as defined by SEQ ID NO 51 or SEQ ID NO 52, wherein the amino acid residues at positions 13 and 44 of SEQ ID NO 51 or 52 are asparagines and wherein at least the asparagine residue at position 3 of SEQ ID NO 51 or 52 has been mutated to an amino acid selected from the group consisting of glutamic acid, lysine, tyrosine, threonine, phenylalanine, leucine, isoleucine, tryptophan, methionine, valine, alanine, histidine and arginine.

The present invention generally pertains to methods of identifying and characterizing host cell proteins. In particular, the present invention pertains to the use of size exclusion chromatography in non-denaturing or denaturing conditions to enrich a sample for host cell proteins and characterize the binding of host cell proteins to a protein of interest.