STRAIN-SPECIFIC AND TISSUE-SPECIFIC EXPRESSION OF MOUSE MAST-CELL SECRETORY GRANULE PROTEASES

As assessed by RNA blot analyses with gene-specific probes, we report that the perivascular connective tissue mast cells (CTMCs) in the ear and skin of BALB/cJ mice contain abundant levels of the mouse mast cel l protease (mMCP) 7 transcript, in addition to those protease transcri pts present in their serosal mast cells (SMCs). High levels of the mMC P-7 transcript also were detected in the ears of WBB6F1/J-+/+, WCB6F1/ J-+/+, WB/ReJ-+/+, and WC/ReJ-+/+ mice. However, the ears of these fou r strains and the SMCs from the WCB6F1/J-+/+ strain but not the BALB/c j strain also contained high steady-state levels of the mMCP-2 transcr ipt. The mMCP-2, mMCP-4, mMCP-5, mMCP-6, and mMCP-7 transcripts were n ot detected in the ears of mast-cell-deficient WBB6F,/J-W/W(v) and WCB 6F1/J-Sl/Sl(d) Sl/Sl(d) mice, indicating that mast cells were the sour ce of these protease transcripts in the +/+ animals. When immunohistoc hemical analyses of serial sections of ear and skin from WBB6F1/J-+/mice were performed with anti-mMCP-2 IgG and anti-mMCP-5 IgG, the peri vascular CTMCs in these tissues were found to express both mMCP-2 and mMCP-5 in their granules. The prominent expression of mMCP-7 in consti tutive perivascular CTMCs indicates that this mast cell has an extende d protease phenotype relative to the SMCs of the same strains. Further , the perivascular CTMCs and SMCs of the +/+ strains differ from those in BALB/cJ mice in their prominent expression of mMCP-2.