Mast cells and their microenvironment: the influence of fibronectin and fibroblasts on the functional repertoire of rat basophilic leukemia cells.
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)
Swieter
M
M
Laboratory of Immunology, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892.
Hamawy
M M
MM
Siraganian
R P
RP
Mergenhagen
S E
SE
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
D005353:Fibronectins