Miniantibodies

Abstract

The usual motivation to create a multivalent molecule is to increase its functional affinity (avidity) to a corresponding multimeric antigen structure, which can be a
cell surface, a virus surface or a fibrous polymer. Obviously, no increase in affinity to a soluble monomeric antigen can be expected. However, an increased functional
affinity to a formally monovalent antigen will usually be observed when it is immobilized on a densely packed surface (e.g. on an ELISA plate or a BIAcore
chip). The increased size of the antibody fragment upon multimerization, in conjunction with higher functional affinity, can also lead to improved tumor localization
(Hu et al. 1996; Todorovska et al. 2001; Deyev et al. 2003; Kubetzko et al. 2006). Besides causing an avidity gain, bivalent binding might also result in
agonistic activity, which may or may not be desired in a particular application.