ALTERATION OF PROTEASE EXPRESSION PHENOTYPE OF MOUSE PERITONEAL MAST-CELLS BY CHANGING THE MICROENVIRONMENT AS DEMONSTRATED BY IN-SITU HYBRIDIZATION HISTOCHEMISTRY

Mouse mast cell protease (MMCP) mRNA expression was examined by in sit u hybridization histochemistry. Peritoneal mast cells (PMCs) of WBBGF( 1)-+/+ mice expressed MMCP-2, MMCP-4, MMCP-5, and MMCP-6 mRNAs, but di d not express MMCP-1 mRNA, When proliferation of PMCs was induced by c ulturing them in methylcellulose with T cell-derived cytokines, cells in mast cell colonies expressed MMCP-1 mRNA. These mast cells were tra nsferred to a suspension culture to induce further proliferation. The phenotype of the resulting PMC-derived cultured mast cells was similar to that of bone marrow-derived cultured mast cells. When 10(5) PMC-de rived cultured mast cells or 105 bone marrow-derived cultured mast cel ls were injected into the stomach wall of mast cell-deficient WBBGF(1) -W/W-v mice, mast cells that appeared in the mucosa and muscularis pro pria were similar to mast cells in the stomach of intact WBBGF(1)-+/mice, indicating the injected cells adapted to a new tissue environmen t. In contrast, when 105 PMCs were injected into the stomach wall of W BBGF(1)-W/W-v mice, the injected PMCs did not adapt to the mucosa. Whe n 20 PMCs were injected, they proliferated and adapted to the mucosal environment. The present results suggest that PMCs adapt to new enviro nments when proliferation occurs before redifferentiation.