Basophils preferentially express mouse mast cell protease 11 among the mast cell tryptase family in contrast to mast cells

Abstract

Tryptases and chymases are the major proteins stored and secreted by mast cells, and they have various biological functions. However, the nature of proteases produced by basophils has been poorly characterized, particularly in mice. mMCP-11 is the most recently discovered mast cell tryptase in mice and was originally identified as Prss34, which is transcribed in some mast cell-like cell lines and at the early stage in the culture of BMMC with IL-3. Curiously, Prss34 is preferentially expressed in the BM and spleen among normal tissues in contrast to other mast cell tryptases. Therefore, it remains elusive what types of cells express mMCP-11 in vivo. Here, we show that mMCP-11 is highly expressed by primary basophils and to a much lesser extent, by some mast cells. Prss34 transcripts were detected abundantly in primary and cultured basophils and very weakly in peritoneal mast cells or cultured BMMC. Conversely, transcripts for mMCP-6 and mMCP-7 tryptases were preferentially expressed by cultured and peritoneal mast cells but not basophils. We established a mMCP-11-specific mAb and showed that mMCP-11 proteins are indeed expressed by primary basophils and those infiltrating the affected tissues during allergic inflammation and parasitic infections. Some primary mast cells also expressed mMCP-11 proteins, albeit at a much lower level. Thus, basophils rather than mast cells are the major source of mMCP-11. This is the first study to demonstrate that mouse basophils produce a trypsin-like protease.

FcεRI, but Not FcγR, Signals Induce Prostaglandin D2 and E2 Production from Basophils

“…Our prior study showed that the number of infiltrative basophils in skin lesions of IgE-CAI was higher than that of dermal mast cells (19.4 cells/mm 2 versus 8.2 cells/mm 2 ). 31 Thus, basophils may be equally or even more important than mast cells as sources of PGD2 production in IgE-CAI. PGD2 is one of the important mediators responsible for the development of IgE-CAI as evidenced by unpublished observation (Y. Matsushima) that the administration of an antagonist against the PGD2 receptor CRTH2 ameliorated skin inflammation.…”

“…Furthermore, bone marrow cells expressing mMCP-8, a specific marker for basophils, 31 were positive for both H-PGDS and mPGES1 by immunohistochemical analysis ( Figure 6B). These results show that basophils express H-PGDS as well as PGES, thereby producing both PGD2 and PGE2.…”

“…Anti-mMCP-8 mAb 31 was conjugated with Alexa 488, and both anti-H-PGDS mAb and anti-mPGES mAb 30 were conjugated with Alexa 647 by using the Alexa Fluor Monoclonal Antibody Labeling kit (Invitrogen). …”

Basophil-associated OX40 Ligand Participates in the Initiation of Th2 Responses during Airway Inflammation

“…2, B and C). In addition, to confirm that the highly enriched cells were indeed basophils, cytospins were stained with mMCP-8, which has been reported as a specific marker for basophils, and Wright-Giemsa staining, respectively (31,36). Immunofluorescence analysis indicated that the population was ϳ100% positive for mMCP-8 (Fig.…”

“…To characterize the sorted BM-Bas, cytospins were made. A part of them were stained with Wright-Giemsa and the others were fixed with 4% (v/v) paraformaldehyde, then permeated with 0.1% (v/v) Triton 100 and blocked with 10% (w/v) bovine serum albumin, stained with purified antimMCP-8 antibody (Ab) (clone TUG8, Biolegend) and FITCconjugated rabbit polyclonal secondary Ab to rat, and counterstained with DAPI (4,6-diamidino-2-phenylindole) (30,31).…”