Evaluation of an immunoaffinity extraction column for enrichment of adducts between human serum albumin and hexahydrophthalic anhydride in plasma

Abstract

An immunoaffinity extraction (IAE) column was prepared for extraction of adducts between human serum albumin (HSA) and hexahydrophthalic anhydride (HHPA). HHPA is a strong sensitizer inducing immunoglobulin E antibodies in vivo. Polyclonal antibodies from a rabbit immunized with keyhole limpet hemocyananin-HHPA conjugate were purified using a Protein A Sepharose gel. To obtain antibodies with optimal affinity towards HHPA-protein adducts, HHPA-specific antibodies were selected using an N-hydroxysuccinimide-Sepharose column coupled with albumin-HHPA conjugate. Antibodies eluted from this column at pH 2.2 were selected to prepare the IAE column. The column was evaluated using 2 mL plasma spiked with HSA-HHPA conjugate. The column was eluted with glycine buffer at pH 2.0. The conjugates in the eluate were hydrolyzed to the corresponding HHP acid and quantified by mass spectrometry. The average recovery of HHPA adducts in 11 experiments was 68% with a coefficient of variation (CV) of 7%. The column's capacity to bind protein-HHPA adducts was found to be linear in the range of 0.15-1.2 nmol conjugate. The evaluation showed that the IAE column had adequate affinity towards the HHPA adducts and that the adducts could be extracted with good recovery and precision from a large volume of plasma.

Identification of Covalent Binding Sites of Phthalic Anhydride in Human Hemoglobin

“…In such instances, the matrix effects may interfere in the analysis, and a sample purification step would be necessary. Johannesson et al (27) have shown that HHPA-adducted human serum albumin can be purified with immunoaffinity chromatography from plasma. This could be applied to the PA adducts as well, but for this procedure, more work has to be performed to obtain a final biological monitoring method.…”

Identification of covalent binding sites of ethyl 2-cyanoacrylate, methyl methacrylate and 2-hydroxyethyl methacrylate in human hemoglobin using LC/MS/MS techniques

“…In addition, Hb from exposed workers should be analyzed to determine the levels of adducts in these subjects. If the adduct levels are found to be too low to be detected, there are ways to solve this problem; e.g., Georgieva et al [31] and Johannesson et al [32] have shown that adducted peptide can be purified using immunoaffinity chromatography. It is also possible worth evaluating if peptides from human serum albumin or other high abundant plasma proteins can be analyzed.…”