Development and validation of a simple antigen–antibody model

Document Type


Publication Date



Department of Physics


A theoretical model for investigating physical phenomena underlying immune complex formation was developed, based on the statistical mechanical theory of associating fluids that identifies each molecule as a hard sphere with a nested point charge and vector dipole. The interaction between binding molecules (epitope–paratope binding) is represented as a cone truncated by two concentric spheres in which the potential energy is a modified square well with respect to particle separation and a square well with respect to mutual molecular orientation. Equilibrium binding results predicted by the model show good agreement with results obtained experimentally for a model system containing a single antigen and a single monoclonal antibody [bovine serum albumin (BSA) – anti‐BSA antibody]. Moreover, values obtained for the system isothermal compressibility and the second virial coefficient by both the model and light scattering experiments also show good agreement with one another.

Publication Title

AIChE Journal