Investigating antibody–antigen binding with atomic force microscopy

Adhesive interactions between antigen–antibody play a central role in immune system operation. The objective of this paper is to detect immune complexes without any label, by using atomic force microscopy (AFM). We have proceeded by imaging antibody (anti-rabbit IgG) or anti-rabbit IgG moieties adsorbed onto mica surface, before and after incubation of two kinds of antigens: a specific (rabbit IgG) and a non-pecific one (sheep IgG). The analysis using the height histograms reveals many interesting features. We propose a general framework for interpreting height histogram measurements, which enable the discrimination between specific and non-specific complexes.