Phagocytic response to fully controlled plural stimulation of antigens on macrophage using on-chip microcultivation system

Phagocytosis as an effector mechanism of the innate immune response could be triggered by attachment of antigens to the surface of macrophages. The protein-based understanding of the signal processing pathways of innate immunity to microorganisms like Toll-like receptors (TLR), nucleotide-binding oligomerization domain (NOD) proteins, and myeloid differentiation primary-response protein 88 (MyD88) families for pathogen-associated molecular patterns (PAMs), has contributed to the development of therapeutics for human immune diseases [1,2]. However, it is still hard to explain the variability of responses caused by a lack of knowledge of the modulation mechanism of the immune response of single macrophages against multiple antigen stimulations. In other words, we still do not know whether signal processing can work simultaneously and independently against a plurality of antigen stimulations in different places on the surface of a single macrophage.To understand the mechanism of complex signal processing that occurs in phagocytosis when there are multiple stimulations to macrophages, we need to give a series of fully controlled stimulations to an isolated single macrophage step-by-step under isolated circumstances. This is because with conventional group-based cultivation in a dish, stimulation of antigens to the target macrophage is usually done in an uncontrolled probabilistic way. Moreover, the physical contact with other macrophages might also influence the phagocytic response of macrophages.In this paper, we report the time course of phagocytosis of an isolated single macrophage against a plurality of stimulations with antigens. In the experiment, to prevent the effects of unexpected factors, we used our on-chip single-cell cultivation system to give fully controlled stimulations to the isolated macrophage, and we then measured its response to those stimulations.Previously, we developed an on-chip single-cell cultivation system exploiting the microfabrication tech