Anaphylactic release of mucosal mast cell granule proteases: role of serpins in the differential clearance of mouse mast cell proteases-1 and -2.
The granule-derived mouse mast cell proteases-1 and -2 (mMCP-1 and -2) colocalize in similar quantities in mucosal mast cells but micrograms of mMCP-1 compared with nanograms of mMCP-2 are detected in peripheral blood during intestinal nematode infection. This differential systemic response was investigated both in vitro and in vivo. Bone marrow-derived mucosal mast cell homologs released similar quantities of mMCP-1 and-2 concomitantly with beta-hexosaminidase in response to calcium ionophore ( approximately 60% release) or IgE/DNP (25% release). In contrast, serum from mice sensitized by infection with Nippostrongylus brasiliensis 10 days earlier contained >1500-fold more mMCP-1 (10,130 +/- 1,609 ng/ml) than mMCP-2 (6.4 +/- 1 ng/ml), but, in gut lumen, the difference was approximately 8-fold. After OVA sensitization, >600-fold more mMCP-1 (7,861 +/- 2,209 ng/ml) than mMCP-2 (12.8 +/- 4.7 ng/ml) was present in blood 1 h after challenge, but, in gut lumen, there were relatively comparable levels of mMCP-1 and -2. To estimate the rates of systemic accumulation and clearance, 10 microg of mMCP-1 or -2 was injected i.p. Plasma levels of injected mMCP-2 peaked (1%) at 15 min then declined, whereas levels of mMCP-1 were maximal (approximately 25%) at 3 h. Inactivation of mMCP-1 with PMSF before injection resulted in mMCP-2-like kinetics, but inhibition of mMCP-1 by serum gave kinetics similar to that of native mMCP-1. mMCP-1 isolated from serum is complexed with serpins and we conclude that both the accumulation and the longevity of mMCP-1 in blood is due to complex formation, protecting it from a pathway that rapidly clears mMCP-2, which is unable to form complexes with serpins.
Pemberton
Alan D
AD
Division of Veterinary Clinical Studies, University of Edinburgh, Easter Bush Veterinary Centre, Roslin, Midlothian, United Kingdom.
Wright
Steven H
SH
Knight
Pamela A
PA
Miller
Hugh R P
HR
D000707:Anaphylaxis / Q000201:enzymology* / Q000276:immunology* / Q000503:physiopathology; D000818:Animals; D015550:Cell Degranulation / Q000276:immunology; D002478:Cells, Cultured; D053818:Chymases; D007114:Immunization; D007413:Intestinal Mucosa / Q000166:cytology / Q000276:immunology; D007700:Kinetics; D008407:Mast Cells / Q000201:enzymology* / Q000276:immunology* / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D046912:Multiprotein Complexes; D009559:Nippostrongylus / Q000276:immunology / Q000472:pathogenicity; D010047:Ovalbumin / Q000276:immunology; D012697:Serine Endopeptidases / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D015843:Serpins / Q000378:metabolism*; D017206:Strongylida Infections / Q000201:enzymology / Q000276:immunology
D046912:Multiprotein Complexes; D015843:Serpins; D010047:Ovalbumin; D012697:Serine Endopeptidases; C083294:chymase 2; D053818:Chymases; C509229:Cma2 protein, mouse