Immunoaffinity extraction of a peptide modified by a small molecule

Comprehensive analysis of MHC ligands in clinical material by immunoaffinity-mass spectrometry

Major histocompatibility complexes (MHC) are expressed on antigen-presenting cells (APC) that display peptide antigens. This is a crucial step to activate a T-cell response. Since immunogenic ligand of MHC is closely related with autoimmunity, inflammatory diseases, and cancer, comprehensive analysis of MHC ligands (the so-called Ligandome) is essential to unveil disease pathogenesis. Recently, immunotherapies such as vaccination have been focused on as new therapies of cancer, HIV, and infectious diseases. Therefore, the importance of comprehensive analysis of MHC ligands is increasing. Mass spectrometry has been the core technology of ligand identification since the 1990s. The sensitivity of mass spectrometers has been improved dramatically in recent years; thus, it enables to identify MHC ligands in clinical materials. This chapter lays out the workflow of MHC ligand identification in clinical materials, especially human bronchoalveolar (BAL) cells. MHC-ligand complexes are enriched by immunoaffinity extraction and captured ligand peptides are identified by LC-MS/MS. MHC class II ligand in BAL cells is described in this text; however, this approach is applicable to MHC class I and other clinical materials such as tissues.

Quantitative analysis of biomarkers, drugs and toxins in biological samples by immunoaffinity chromatography coupled to mass spectrometry or tandem mass spectrometry: A focused review of recent applications

Immunoaffinity chromatography (IAC), mass spectrometry and especially tandem mass spectrometry (MS/MS) represent the most efficient and reliable analytical techniques for specific isolation, unequivocal identification and accurate quantification of numerous natural and synthetic substances in biological samples. This review article focuses on the combined use of these outstanding methodologies in basic and clinical research and in life sciences for the quantitative analysis of low- and high-molecular mass biomarkers, drugs and toxins in urine, plasma or serum samples, in tissue and other biologicals systems published in the last decade. The analytes discussed in some detail include the biomarkers of oxidative stress 15(S)-8-iso-prostaglandin F(2alpha) {15(S)-8-iso-PGF(2alpha)} and 3-nitrotyrosine, the major urinary metabolite of the lipid mediators cysteinyl leukotrienes, i.e., the leukotriene E(4) (LTE(4)), melatonin, and the major collagen type II neoepitope peptide in human urine.

Development of immunoaffinity restricted access media for rapid extractions of low-mass analytes

Restricted access media using antibodies as immobilized ligands were developed for the rapid and selective capture of small analytes by immunoextraction, giving rise to materials referred to as immunoaffinity restricted access media (IA-RAM). To make such a material, intact antibodies for the desired target were first immobilized onto porous silica, with antibodies at or near the outer surface of the support then being treated with papain (or a related agent) to release and remove their binding domains. The result was a support in which only antibodies deep within the pores remained intact and able to bind to the target. Items evaluated in the development of such media included the immobilization method used for the antibodies, the pore size of the support, and the amount of papain and time that were used for support treatment. A theoretical model was also developed to describe the extent of binding domain removal based on the measured polypeptide content of the IA-RAM support before and after treatment with papain. The final optimized conditions for making the IA-RAM supports were used to prepare columns that contained antifluorescein antibodies. Injections of fluorescein and fluorescein-labeled bovine serum albumin onto these IA-RAM columns gave selective and quantitative extraction of fluorescein in 1-2 s. This approach can be used with other antibodies and low-mass targets and should be valuable for such applications as the rapid separation of drugs from drug-protein complexes or the isolation of labeled/modified peptides from intact proteins that contain the same modification or label.