Immunohistologic characterization of epitheloid cells in Crohn's granulomas.

Monoclonal antibodies reactive with monocyte/macrophages were used to characterize the nature of epitheloid cells in Crohn's granulomas. Six micron continuous frozen sections were studied in 12 specimens. A series of monoclonal antibodies was used to stain sections by the avidin-biotin complex method. Epitheloid cells in Crohn's granulomas reacted with anti-25F9 and anti-HLA-DR antibodies, but did not respond to anti-Leu M1, anti-Leu M2, anti-Leu M3 nor anti-Leu M5 antibodies. These results suggest that epitheloid cells in Crohn's granulomas may be activated macrophages.