Separation and analysis of charged isomers of monoclonal immunoglobulin G by ceramic hydroxyapatite chromatography.

Analysis of monoclonal antibody (MAb) heterogeneity caused by posttranslational modifications is important for pharmaceutical quality assurance of antibody drugs. In this study, by employing small ceramic hydroxyapatite (HAp) particles that were self-manufactured to have a 2.5-µm diameter, we attempted to separate and analyze MAb isomers. The MAb without N-linked oligosaccharides could be separated by 2.5-µm HAp chromatography as well as MAb with N-linked oligosaccharides. Hence, a variety of N-linked oligosaccharides do not appear to be involved in the separation mechanism of HAp chromatography. However, there is a difference in retention time between MAb with and without N-linked oligosaccharides, meaning that the presence of N-glycan could influence the retention time of HAp chromatography. Subsequently, the MAb fractions separated by 2.5-µm HAp chromatography were analyzed by isoelectric focusing, and seven isomers of the MAb having different isoelectric points (pI) were identified. The MAb isomers were eluted in order of lower pI isomers with sodium phosphate buffer, and enzyme-linked immunosorbent assay indicated the immunoreactivity of the fraction including the lowest pI isomers to be remarkably reduced. This study yielded details of the separation behavior of HAp chromatography owing to 2.5-µm HAp particles.

Development of fluoroapatite chromatography for the purification of monoclonal antibody.

Monoclonal antibody was purified from tissue culture fluid using ceramic fluoroapatite chromatography. Efficiency of the capture step was shown to be sensitive to pH and phosphate concentration. More than 90% of host cell proteins were removed by ceramic fluoroapatite chromatography. Studies regarding pH control and metal adsorption are presented.

Purification of lactoferrin using hydroxyapatite.

Lactoferrin is an important nutriceutical with various physiological functions. It is present in whey at very low concentrations. This work describes a mixed-mode (hydroxyapatite) chromatography method for one-column fractionation of lactoferrin from whey. Lactoperoxidase, a protein with similar molecular weight and isoelectric point, was initially desorbed from the matrix under isocratic conditions. Lactoferrin was obtained in homogeneity without lactoperoxidase activity and free from other major whey proteins such as alpha lactoalbumin and beta lactoglobulin.

Single-step purification of pepsin-derived monoclonal antibody fragments from crude murine ascitic fluids by ceramic hydroxyapatite high-performance liquid chromatography.

Ceramic hydroxyapatite (CHT) high-performance liquid chromatography (HPLC) is used to purify a variety of classes of monoclonal antibodies (mAbs) from crude murine ascites fluids. We report here that this method is also applicable for simple and efficient purification of many mAb fragments that are generated by pepsin treatment of crude ascites. F(ab')(2) fragments were quantitatively generated from IgG(1) mAbs in ascitic fluids by incubation with pepsin for 6 h at pH 3.9-4.1. Under the same conditions, pepsin also cleaved unwanted ascites components, such as albumin and transferrin to very low molecular weight polypeptides. The F(ab')(2) fragments, but not the low molecular weight products, selectively bound to and were eluted from the CHT column using a linear gradient of phosphate ion concentration over 15 min. The recovery of the F(ab')(2) fragments by CHT-HPLC was >90%. This method also allowed single-step purification of mAb fragments from distinct IgG subclasses (IgG(2a) and IgG(2b)) and IgM directly from crude digested ascitic samples. This CHT-HPLC method combined with direct pepsinolysis of murine ascites is a useful strategy for rapid purification and characterization of many types of mAb fragments.