JAM-C is a member of the Ig-superfamily that localizes to cell-cell contacts and is specifically enriched at tight junctions. Originally detected on endothelial cells (ECs), JAM-C has since been reported to be expressed on numerous other cell types such as spermatids, epithelial cells, smooth muscle cells, fibroblasts and Schwann cells. As such JAM-C has been associated with numerous biological functions but most notably it has been studied in the context of vascular and inflammatory responses1. Despite a growing interest in this complex molecule there remain many unanswered questions with respect to the expression and functions of JAM-C. In the present study we sought to investigate the expression and regulation of expression of EC JAM-C under inflammatory scenarios. The expression of EC JAM-C was investigated in mouse ear skin and cremaster muscle by immunofluorescent staining and confocal microscopy using whole-mount tissues. With this approach JAM-C was found to be strongly expressed at junctions of ECs in capillaries and venules, but not arterioles. The venular expression of JAM-C was unaltered in ears stimulated with intradermal C5a (1µg), or the chemokines KC and MIP-2 (both at 500ng) but was significantly reduced in LTB4-stimulated tissues (300ng). The latter occurred in a dose and time-dependent manner with reduced expression of JAM-C being noted at 30 mins, peaking at 4 h and returning back to normal levels by 24 h post LTB4 administration. In addressing the mechanism of JAM-C cleavage, studies with neutrophil-depleted mice and neutrophil elastase (NE) KO mice demonstrated a role for neutrophil-derived NE in LTB4-induced loss of EC JAM-C. Local administration of LTB4 induced neutrophil reverse transmigration in mouse cremasteric venules (analysed by confocal intravital microscopy) and this was associated with lung inflammation. These results suggest that loss of local EC JAM-C can lead to disrupted modes of neutrophil transmigration which can in turn contribute to secondary organ inflammation2. Collectively, our data indicate that the expression and regulation of expression of EC JAM-C is vessel type and stimuli specific, respectively, and that JAM-C is shed from ECs after LTB4 stimulation in a neutrophil and NE dependent manner, a phenomenon that can contribute to turning a local inflammatory response to a systemic reaction.