<p>PBMCs from both GPA patients and healthy controls were cultured in the presence of 25 ng/ml M-CSF and 100 ng/ml RANKL, and stained for the presence of TRAP expression after 9 days in culture. Nuclei were counterstained with hematoxylin. MNGs with three or more nuclei and TRAP expression (purple cytoplasmic stain) were counted. Few MNGs were generated at day 9 from the PBMCs of healthy controls (A); in contrast, large MNG with numerous nuclei were formed from patients with GPA (representative field shown in B). Further, the generated cells were able to degrade bone matrix. Numerous large pits were formed by GPA PBMCs (D) as compared to the healthy control PBMCs after 9 days (C). C and D are representative of 3 independent experiments. Original magnification x 10.</p
