ABSTRACT
The Syrian hamster embryo (SHE) cell transformation assay is widely used to screen chemicals for carcinogenic potential. However, the biochemical mechanisms of transformation in SHE cells are incompletely understood relative to other rodent systems. Thus identification of proteins which change during transformation can provide clues to biochemical mechanisms. Previously, we published a map of SHE cell proteins based on comparisons to other maps. In this report we provide direct sequence analysis of numerous proteins which were previously identified solely by electrophoretic mobility. Protein sequencing verified original spot identifications and extended the range of identified proteins. The updated map will assist in evaluating biochemical mechanisms of morphological transformation in hamster cells.
Subject(s)
Electrophoresis, Gel, Two-Dimensional/methods , Embryo, Mammalian/chemistry , Peptide Mapping/methods , Proteins/analysis , Sequence Analysis/methods , Animals , Cell Line , Cricetinae , Databases, Factual , Mesocricetus , Mice , RatsABSTRACT
Assessment of the allergenic potency of enzymes involves the use of a guinea pig model in which specific IgG1 antibody titers are used as the endpoint. The in vivo passive cutaneous anaphylaxis (PCA) assay is used to measure specific IgG1 antibody. This report describes the development and validation of an enzyme-linked immunosorbent assay (ELISA) to measure guinea pig specific IgG1 antibody as an in vitro alternative to the PCA assay. Cross reactivity of various rabbit and mouse (monoclonal) anti-guinea pig IgG1 preparations were evaluated using purified IgG1 and IgG2 from serum of guinea pigs immunized with ovalbumin. The two subclasses of guinea pig IgG were purified by first using Protein A affinity chromatography, followed by anion exchange chromatography and fluid phase isoelectric focusing. Affinity-purified rabbit anti-guinea pig IgG1 was shown to have minimal cross reactivity toward IgG2, while providing a strong signal with IgG1. The ELISA was designed as an antigen capture system in which the following are added in sequence: (1) enzyme antigen (passively adsorbed to the plate), (2) diluted serum samples from guinea pigs immunized with enzyme, (3) affinity-purified rabbit anti-guinea pig IgG1, (4) alkaline phosphatase-conjugated donkey anti-rabbit IgG, and (5) p-nitrophenyl phosphate substrate. Three replicate ELISA and PCA analyses were conducted on sera samples of varying titers from guinea pigs immunized with either Alcalase (protease), BPN' (protease), and Termamyl (amylase) enzyme. The correlation coefficients (r2) between the ELISA and PCA assay for Alcalase, BPN', and Termamyl were 0.826, 0.945, and 0.755, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Immunoglobulin G/analysis , Passive Cutaneous Anaphylaxis , Animals , Antibodies, Monoclonal/immunology , Antibody Specificity , Cross Reactions , Electrophoresis, Polyacrylamide Gel , Enzyme-Linked Immunosorbent Assay , Female , Guinea Pigs , Immunoglobulin G/isolation & purification , Isoelectric Focusing , Ovalbumin/immunologyABSTRACT
Allergic asthma can result when reactive low-molecular-weight chemicals (LMWCs) haptenate carrier proteins to form immunogenic conjugates, which then induce specific allergic antibodies. As part of an overall assessment process for evaluating the allergenic potential of LMWCs, an in vitro test for detecting the covalent derivatization of proteins by LMWCs was developed. In the assay, globulin-free serum albumins were incubated with increasing concentrations of a given LMWC and the mixtures separated via reversed-phase high-performance liquid chromatography (HPLC). Derivatization was monitored by shifts in the retention time of native versus modified protein. Retention time shifts were seen for most haptens when incubated with human serum albumin at a 50:1 (hapten:protein) starting molar ratio. Some haptens changed the retention time of the protein at a 5:1 initial ratio. Almost all chemicals that non-covalently bind to proteins did not change the protein retention time, even when incubated at 1500:1 molar ratios. The screen correctly identified 12/14 known human allergenic haptens and 23/24 non-allergenic LMWCs. It cannot detect sensitizers which must be metabolized into reactive haptens. This screen can be incorporated into an overall risk assessment approach for evaluating chemicals as respiratory allergens.
