MCs and DCs are found in close proximity in human tissue. (A) Representative immunohistochemical labeling of MCs (tryptase, brown) and DCs (DC-SIGN, pink) in 5-µm-thick tissue sections from human donors for normal colon, small intestine, lung, and skin. Boxed regions are enlarged to demonstrate where cells are likely in contact (brown and pink pixels are immediately adjacent, indicated by arrows). Images are brightness and contrast enhanced. Bars, 50 µm. (B) Bar graph indicating the percentage of MCs in contact with DCs within each type of tissue from each donor tested. Values are means from 10 fields of view for each tissue from each donor. Total numbers of MCs counted for each donor—used to calculate the percentages—are immediately below the bar they represent. Error bars are SEM.