title: Mast cells and their microenvironment: the influence of fibronectin and fibroblasts on the functional repertoire of rat basophilic leukemia cells.
abstract: To determine how the microenvironment in which mast cells are located may influence their function, we explored the effects of fibronectin and fibroblasts on histamine secretion in vitro from a mast cell model, the rat basophilic leukemia (RBL-2H3) cell line. RBL-2H3 cells bound specifically to fibronectin-coated surfaces. Binding was maximal by 1 hour, was not detectable at 0 degrees C or in the absence of Ca++, and was inhibited by preincubating the cells with a synthetic peptide containing the RGD sequence. Adherence to fibronectin stimulated RBL-2H3 cell spreading with a concomitant reorganization of the cytoskeleton and a repositioning of the cytoplasmic granules to the cell periphery. Although adherence to fibronectin did not by itself induce histamine release, when stimulated by either immunologic or non-immunologic means, fibronectin-adherent cells released dramatically more histamine than cells plated in wells coated with BSA only. Thus, RBL-2H3 cells bind specifically to fibronectin, and in so doing are stimulated to undergo changes in morphology and enhanced responsiveness to secretory stimuli. RBL-2H3 cells grown in coculture with 3T3 fibroblasts, but not RBL-2H3 cells grown alone, became responsive to the polymeric synthetic secretagogue Compound 48/80 and the neuropeptide Substance P. Maximum sensitivity to Compound 48/80 was attained by the second week in coculture. Histamine release was dose-dependent, noncytotoxic and occurred even in the absence of extracellular Ca++. Contact between the 2 cell types appeared to be a critical factor. RBL-2H3 cells, separated from 3T3 cells by a 0.45 micron filter, failed to secrete histamine in response to Compound 48/80.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Laboratory of Immunology, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892.
authors.forename: M
authors.initials: M
authors.lastname: Swieter
authors.forename: M M
authors.initials: MM
authors.lastname: Hamawy
authors.forename: R P
authors.initials: RP
authors.lastname: Siraganian
authors.forename: S E
authors.initials: SE
authors.lastname: Mergenhagen
mesh_terms: D000818:Animals; D005347:Fibroblasts / Q000502:physiology*; D005353:Fibronectins / Q000502:physiology*; D006636:Histamine Release / Q000502:physiology*; D015471:Leukemia, Basophilic, Acute / Q000473:pathology*; D008407:Mast Cells / Q000502:physiology*; D051381:Rats; D014407:Tumor Cells, Cultured
chemical_list: D005353:Fibronectins