Adhesion of mouse mast cells to fibroblasts: Adverse effects of steel (SI) mutation

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Abstract
Mouse bone marrow-derived cultured mast cells proliferate on +/+ mouse embryo-derived 3T3 fibroblasts, but not on SI/SId mouse embryo-derived 3T3 fibroblasts, in the absence of IL-3 and IL-4 (Fujita et al: Proc. Natl. Acad. Sci. U.S.A. 86:2888–2891, 1989). To further characterize the mast cell-fibrpblast interactions and the effects cf SI mutation, we tried to analyze the adhesion of cultured mast cells to 3T3 fibroblasts in vitro. Mast cells plated onto NIH/3T3 fibroblasts showed marked adhesion within 30 min, which reached a plateau after 3 h. The numbers of adhered mast cells were linear over the range of 103 to 5 × 105 cells inoculated into each (2 cm2) of 24 multiwells. Adhesion required active energy production and the presence of divalent cations. It was not inhibited byan RGD-containingpeptide, an anti-LFA-1 antibody, or asialofetuin. Mast cells adhered efficiently to the eight 3T3 cell lines derived from +/+ mouse embryos, but not to the eight 3T3 cell lines derived from SI/SId mouse embryos. Adhesion to mouse spleen-derived fibroblasts lacking mast cell-supporting activitywas comparable to that to SI/SId/3T3 cells. The failure of mast cells to adhere to fibroblasts with the SI mutations was not due to a production of a diffusible inhibitor by the latter. These results indicate that production of wild type SI gene product by fibroblasts is mandatory for adhesion/migration, as well as for proliferation of mast cells on them, and that the coculture system should be useful for the biochemical and molecular analysis of these interactions.