Background: The contact hypersensitivity (CHS) murine model is a model used to investigate the role of the adaptive immune response following an epicutaneous application of small allergen mediating compounds called haptens. Although, studies have looked into the dynamic behaviour of immune cells during the elicitation phase of CHS, their behaviour during the sensitisation phase is not well-defined.
Aim: We aim to understand the spatiotemporal behaviour of dermal dendritic cells (dDCs), perivascular macrophages (PVM) and mast cells during the sensitisation phase.
Methods: Using intravital multiphoton microscopy, we have imaged changes in the behaviour of the above-mentioned immune cell subsets within the ear skin following sensitisation with the hapten 2,4-dinitro-1-fluorobenzene (DNFB).
Results: From our results we have observed that immediately following DNFB sensitisation dDCs exhibit predominantly stable interactions with sessile PVM. However, mast cell degranulation initiates a change in the behaviour of these immune cells resulting in the dissociation of stable dDCs. Further exploration into the mechanism behind this behavioural change signifies the important role of mast cell granules and mast cell-derived mediators in influencing DC migratory behaviour prior to their migration to the draining lymph nodes.
Conclusion: Our findings have identified a cellular complex consisting of DC-PVM-mast cells that is involved in mediating the sensitisation phase of CHS. Further investigation into the molecular mechanisms of this complex will give us an in-depth understanding of the role of these immune cells in mediating skin-related inflammation.