PGE₂-receptor subtype EP4-dependent adherence of mastocytoma P-815 cells to matrix components in subcutaneous tissues overlaying inside surface of air pouch cavity in CDF1 mouse

Objectives: It remains to be fully clarified how adhesion of mast cells is regulated in vivo. We previously reported that PGE₂-receptor EP4 stimulated the adhesion of mouse mastocytoma P-815 cells to plate-bound fibronectin. Our purpose in this study is to evaluate the adhesion using a system, which can mimic the in vivo adhesion. Methods: P-815 cells were transplanted in an air pouch produced in the transplantable mice, CDF1. The number of cells that adhere to the subcutaneous tissues overlaying the inside cavity surface was determined. Results: The number of adhered cells was decreased in mice administered with ibuprofen or an EP4 antagonist, ONO AE3-208. A local administration of PGE₂ or a phorbol ester, PMA, increased the number of adhered cells, which was also suppressed in the mice treated with ONO AE3-208. Conclusion: Our results suggest that PGE₂-mediated adhesion of P-815 cells in the subcutaneous tissues of the air pouch is mediated by the EP4 subtype.