Differential expression of integrin subunits on adherent and nonadherent mast cells

Abstract

Mast cell progenitors arise in bone marrow and then migrate to peripheral tissues where they mature. It is presumed that integrin receptors are involved in their migration and homing. In the present study, the expression of various integrin subunits was investigated in three systems of adherent and nonadherent mast cells. Mesentery mast cells, freshly isolated bone marrow-derived mast cells (BMMC) and RBL-2H3 cells grown attached to tissue culture flasks are all adherent mast cells and peritoneal mast cells, and cultured BMMC and RBL-2H3 cells grown in suspension represent nonadherent mast cell populations. Pure populations of mast cells were immunomagnetically isolated from bone marrow, mesentery and peritoneal lavage using the mast cell-specific monoclonal antibody AA4. By immunomicroscopy, we could demonstrate that all of these mast cells expressed α4, α5, α6, ß1 and ß7 integrin subunits. The expression of the α4 integrin subunit was 25% higher in freshly isolated mesentery mast cells and BMMC. Consistent with the results obtained by immunomicroscopy, mesentery mast cells expressed 65% more mRNA for the α4 integrin subunit than peritoneal mast cells. In vitro studies were also conducted using the rat mast cell line RBL-2H3. RBL-2H3 cells grown attached to the tissue culture flasks or as suspension cultures expressed the same integrin subunits identified in bone marrow, mesenteric and peritoneal mast cells ex vivo. Similarly, the expression of α4 integrin was higher in adherent cells. Therefore, α4 integrins may play a critical role in the anchorage of mast cells to the extracellular matrix in bone marrow and in peripheral tissues.

Mast cell repopulation of the peritoneal cavity: contribution of mast cell progenitors versus bone marrow derived committed mast cell precursors

“…A previous investigation from our laboratory has shown that while mast cells freshly isolated from rat bone marrow express the integrin subunits α4, α5, α6, β1 and β7 on their surface, the more mature, adherent mast cells expressed significantly more α4 integrin [41]. This change in expression of α4 integrin may be related to the release of MCp from the bone marrow to populate peripheral sites.…”

Mechanical loading promotes mast cell degranulation via RGD-integrin dependent pathways

“…Although a typical consequence of compromised cell-ECM interactions is cell death, RBL cells have been shown to be viable in non-adherent conditions (Grodzki et al, 2003). This is a result that is consistent with our findings.…”

A Pathogenetic Role for Mast Cells in Experimental Crescentic Glomerulonephritis

“…Their major role in disease was originally described as the major effector cell in the pathogenesis of allergic reactions (2). Mast cells derive from committed bone marrow precursors that migrate to peripheral tissues, where they fully mature into phenotypically distinct mast cells (3). Two phenotypically distinct mast cell populations have been described in humans on the basis of their neutral protease composition: The MC T (containing tryptase) and the MC TC (containing tryptase and chymase).…”