Tissue-dependent alteration of protease expression phenotype in murine peritoneal mast cells that were genetically labeled with green fluorescent protein

The changing process of protease expression phenomast type was studied after transplantation of peritoneal cells (PMCs). To pursue the fate of the transplanted PMCs, we obtained PMCs from WBB6F₁-ckit⁺/c-kit⁺ mice with a transgene encoding green fluorescent protein (GFP). A large (n = 10⁴) or small (n = 500) number of PMCs was injected into the stomach wall of genetically mast cell-deficient WBB6F₁-c-kit^w/ c-kit^wv mice without the GFP transgene. The original PMCs expressed messenger (m) RNAs of both mast cell carboxypeptidase A (MC-CPA) and mouse mast cell protease (mMCP)-2. The MC-CPA⁺/mMCP-2⁺ phenotype did not change in both the muscularis propria and mucosa when 10⁴ PMCs were injected. In contrast, when 500 PMCs were injected, the mast cells that developed in the muscularis propria showed MCCPA⁺/mMCP-2^- phenotype and those that appeared in the mucosa showed MC-CPA^-/mMCP-2⁺ phenotype. On day 1 after the injection of 500 PMCs, only ∼20 GFP⁺ cells were detected in the muscularis propria and no GFP⁺ cells in the mucosa. The proportion of Alcian blue⁺ cells decreased until day 7 and increased thereafter. The GFP⁺ but Alcian blue^- cells were considered as degranulated PMCs. The remarkable decrease or degranulation seemed to be necessary for the alteration of protease expression phenotype.