Label-free real-time monitoring of the BCR-triggered activation of primary human B cells modulated by the simultaneous engagement of inhibitory receptors.

Today, there is an intense demand for lab-on-a-chip and tissue-on-a-chip applications in basic cell biological research and medical diagnostics. A particular challenge is the implementation of advanced biosensor techniques in point-of-care testing utilizing human primary cells. In this study, a resonant waveguide grating (RWG)-based label-free optical biosensor technique has been applied for real-time monitoring of the integrated responses of primary human tonsillar B cells initiated by B cell receptor (BCR) and modified by FcγRIIb and CR1 engagement. The BCR-triggered biosensor responses of resting and activated B cells were revealed to be specific and dose-dependent, in some cases with strong donor dependency. Targeted inhibition of Syk attenuated the label-free biosensor response upon BCR stimulation. Indifferent protein human serum albumin (HSA) did not interfere with the recorded signal to BCR stimulation. Simultaneous engagement of BCR and FcγRIIb modulated the kinetic signal of the cells. Activated and resting B cells exhibited different response profiles upon simultaneous engagement of BCR and CR1. This advanced approach has the potential to decipher interfering signaling events in human B cells, manage differences between activated and resting B cell states, helping to understand the actual integrated response of these immune cells, and could be useful in the point-of-care diagnostic testing on human primary cells.