Novel polyol-responsive monoclonal antibodies against extracellular β-D-glucans from Pleurotus ostreatus.

Abstract

β-D-glucans from mushroom strains play a major role as biological response modifiers in several clinical disorders. Therefore, a specific assay method is of critical importance to find useful and novel sources of β-d-glucans with anti-tumor activity. Hybridoma technology was used to raise monoclonal antibodies (Mabs) against extracellular β-d-glucans (EBG) from Pleurotus ostreatus. Two of these hybridoma clones (3F8_3H7 and 1E6_1E8_B3) secreting Mabs against EBG from P. ostreatus were selected and 3F8_3H7 was used to investigate if they are polyol-responsive Mabs (PR-Mabs) by using ELlSA-elution assay. This hybridoma cell line secreted Mab of IgM class, which was purified in a single step by gel filtration chromatography on Sephacryl S-300HR, which revealed a protein band on native PAGE with Mr of 917 kDa. Specificity studies of Mab 3F8_3H7 revealed that it recognized a common epitope on several β-d-glucans from different basidiomycete strains as determined by indirect ELlSA and Western blotting under native conditions. This Mab exhibited high apparent affinity constant (KApp) for β-d-glucans from several mushroom strains. However, it revealed differential reactivity to some heat-treated β-d-glucans compared with the native forms suggesting that it binds to a conformation-sensitive epitope on β-d-glucan molecule. Epitope analysis of Mab 3F8_3H7 and 1E6_1E8_B3 was investigated by additivity index parameter, which revealed that they bound to the same epitope on some β-d-glucans and to different epitopes in other antigens. Therefore, these Mab can be used to assay for β-d-glucans as well as to act as powerful probes to detect conformational changes in these biopolymers.