Mast cells and dendritic cells form synapses that facilitate antigen transfer for T cell activation.
Bottom Line: Direct cellular contact differentially regulates the secreted cytokine profile, indicating that MC modulation of DC populations is influenced by the nature of their interaction.Synapse formation requires integrin engagement and facilitates the transfer of internalized MC-specific antigen from MCs to DCs.The transferred material is ultimately processed and presented by DCs and can activate T cells.
Affiliation: Department of Pathology, The University of New Mexico School of Medicine, Albuquerque, NM 87131.Show MeSH
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Mentions: MCs and DCs are known to localize to the same tissues. We used immunohistochemistry (IHC) to assess whether MCs and DCs are found within close proximity in human tissue. 5-µm sections of normal human colon, intestine, lung, skin, and tonsil were each obtained from five different donors and labeled to detect MCs (Fig. 1 A, tryptase, brown; Walls et al., 1990) and DCs (Fig. 1 A, DC-SIGN, pink; Bergman et al., 2004; van Gisbergen et al., 2005a,c). Labeling of tonsil tissue served as the control, and negative controls were run with all IHC reactions (Fig. S1). IHC revealed that it is common to find MCs and DCs in close proximity (Fig. 1 A, arrows). To quantify the potential for cell–cell contacts, we determined the percentage of MCs that were immediately adjacent to a DC and found this value to be consistently high across all donors and tissue types (Fig. 1 B). It should be noted that in addition to DCs, there are other cells that express DC-SIGN, such as alveolar macrophages (Soilleux et al., 2002). However, within the multiple subsets of DCs, DC-SIGN+ DCs have been detected in the dermal layer of the skin (Geijtenbeek et al., 2000), intestine (Jameson et al., 2002), colon (Soilleux et al., 2002), and lung (de Witte et al., 2008), thus motivating the use of this marker in the IHC experiments. These results confirm that MCs and DCs are found within close proximity and suggest that direct MC–DC interactions could occur in vivo.
Affiliation: Department of Pathology, The University of New Mexico School of Medicine, Albuquerque, NM 87131.