IF was performed on RA, OA, and NL ST sections: A) For IF histology, samples were incubated with mouse anti-human Id1 antibody then followed with a fluorescent conjugated secondary antibody. Samples were stained with DAPI (blue) and images merged. Id1 expression is clearly shown in green (images were taken at 400×). IHC was also performed on RA, OA, and NL ST sections as described. As shown, Id1 could be seen up-regulated in RA vascular tissue by IF staining and IHC. B) The percentage of cells expressing Id1 were analyzed on ECs with a significantly higher percentage of Id1 expressing ECs in RA compared to NL and OA ST (n = number of patients). C) For merged IF histology, samples were incubated with mouse anti-human Id1 and rabbit anti-human vWF antibodies. This was followed by fluorescent conjugated secondary antibodies and images were merged. Id1 expression is clearly shown in red and vessels as defined by vWF expression are shown in green (images taken at 400×). Merged vessel regions shown in yellow are due to Id1 expressing EPCs. D) The percentages of Id1 positive tubes in each of the tissues were calculated and graphed. Id1 containing vasculature was significantly higher in RA compared to NL and OA ST (400×, n = number of patients).
Isozaki et al. Arthritis Research & Therapy 2014 16:R68 doi:10.1186/ar4507