Figure 2. Cell surface gated activation of the AND antibody.

(a) An in vitro AND-gated antibody can be directed to bind to a cell surface only in the presence of two inputs. (b,c) Flow cytometry traces and corresponding percentage of labelled cells for inhibited antibody added to HEK cells expressing different input combinations. A higher percentage of labelled cells is observed where inhibited antibody is added to cells expressing both cell surface lysozyme and secreted phosphatase as inputs (HEK-lys+-seap+ cells, dark blue). Positive control (shown in pink) is cAbLys3 wild type added to cells expressing cell surface lysozyme. The differences to other conditions can be seen clearly. (d,e) The AND-Ab also responds to indirect triggering of inputs. Relaying of an indirect TNF-α cytokine signal using HEK cells (HEK-Blue Null1 (NFκB-seap+) HEK293T cells stably expressing NF-κb-inducible SEAP reporter construct under IFN-β minimal promoter) generates the SEAP input only under the indirect control of stimulation by the IFN-β minimal promoter. In this more complex cellular system, the AND-Ab shows a similar trend in its significant response to the dual inputs. Error bars were calculated using the s.d. of measurements taken in triplicate.