Mast cell HMC-1 migration towards the lung type II epithelium cells, A549. Specimens stained with a mouse anti-human mast cell 229; kidney juxtaglomerular CE diluted 1/5000 show immunoreactivity for HMC-1 mast cells. A, HMC-1 are not detected among the lung carcinoma cells after 24 h of cell co-culture. B and C, Solitary cells and a large number of cells can be detected after 72 and 96 hours of cell co-culture, respectively. Original magnification × 200. Mast cell immunoreactivity indicated by arrow.