Investigation of the Relationship between in Vitro ELISA Measures of Immunoreactive Soy Globulins and in Vivo Effects of Soy Products

Concentrations of glycinin and β-conglycinin were determined in 15 soy products using various enzyme-linked immunosorbent assay (ELISA) formats with specific polyclonal antisera (Pabs) and (or) monoclonal antibodies (Mabs). Nine of these products were evaluated in vivo for apparent digestibility of nitrogen and plasma anti-soy antibody titers in preruminant calves. In inhibition ELISAs, Mabs led to much higher values for antigen concentrations than Pabs. Compared to inhibition ELISAs with Pabs, two-site ELISAs associating Mabs and Pabs gave similar values for glycinin and higher values for β-conglycinin. However, in vitro tests which best predicted in vivo responses to soy were those using inhibition with Pabs, particularly against native β-conglycinin: with antigen concentrations correlation coefficients were negative for apparent digestibility of nitrogen and positive for anti-soy antibody titers. However, Mabs were more powerful tools for studying effects of treatments on soy immunoreactivity.