Quantitative analysis of multiple V-region interactions among normal human IgG

There is to dale no quantitative method for scoring putative V-region interactions among serum antibodies, and the available qualitative techniques are not amenable to routine utilization. This deficit may explain the paucity of observations on the characteristics of the immune network, in contrast with the multiplicity of phenomenological descriptions on idiotype regulation. We describe here a novel methodology that uses isoelectric focusing (IEF) to resolve human F(ab')(2) preparations from large pools of normal serum IgG into multiple bands, and computer-aided data processing to analyze interactions between the resulting blotted proteins and normal serum IgG from individual donors. Our results show that in all normal human sera rested, there are IgG-mediated interactions with a large number of IEF fractions of human F(ab')(2). These interactions are V region specific, as assessed by inhibition experiments and by the lack of binding of IgG monoclonal antibodies, and are characterized by average affinities that are in the micromolar range, as measured by surface plasmon resonance.