What is avidity?

Binding events between a T cell and its target tumor cell determine the initiation of immunological synapse formation and T-cell activation. Cell–cell interactions are, therefore, crucial parameters to consider when trying to comprehend T cell response processes.

Cell avidity defines the total intercellular force between multiple parallel interactions, including co-receptor binding, TCR clustering, cell adhesion proteins, and even orientations and valencies.

Compared with affinity, cell avidity provides a more complete and physiologically relevant picture that reflects the bona fide interaction between effector cells and tumor cells. These interactions serve to better predict cellular responses and outcomes during immunotherapy.

Why cell avidity? Filling the scientific gap

The field of immuno-oncology lacks a proper understanding of what defines a good therapy.
The approaches commonly used today to select the best immunotherapeutic effector cells include surface plasmon resonance (SPR) affinity studies, tetramer staining, and
functional assays.

Results from affinity and tetramer assays are inconsistent and do not correlate linearly with immune cell response. Functional assays, such as IFN-γ secretion and cell killing, are more predictive of effector response in vivo but are time-consuming and inconsistent between experiments or assays (Sibener et al., (2018) CellZhang et al., (2016) Science Translational Medicine).

Through avidity measurements, the z-Movi® can help researchers investigating cell interaction properties that correspond to immune cell response in a predictive, reproducible, and fast manner. All this at a high-throughput and single-cell level, without compromising cell viability.