Intestinal mucosa-associated bacteria modulate rat mast cell reactivity

Int J Immunopathol Pharmacol. Jan-Apr 1999;12(1):31-6.


It is well known that in some conditions bacteria of physiological flora of gastrointestinal tract may become pathogenic. Each complaint which causes injury of gastrointestinal wall integrity permits bacteria to penetrate the tissues and affect the tissue cells. Since mast cells represent one of very important and numerous cellular elements of the gastrointestinal tract walls, bacteria can exert the effects on them. Therefore, the aim of our study was to examine the influence of four strains of intestinal mucosa-associated bacteria--Bacteroides thetaiotaomicron, Bacteroides fragilis, Bifidobacterium adolescentis and Escherichia coli on the mast cell reactivity. Our experiments were performed in vitro on isolated rat peritoneal mast cells and the reactivity of these cells was estimated on the basis of histamine release. We used the suspensions of whole bacteria, killed by heating at 65 degrees C. We have noticed that the magnitude of bacteria-induced histamine release from mast cells was very low (up to 6.0%) when compared with histamine release induced with Con A, compound 48/80 and TNF-alpha. However, all studied bacteria changed the reactivity of mast cells in anaphylactic (with ConA) and anaphylactoid (with compound 48/80) reactions. After 40 min preincubation with B. thetaioataomicron, B. fragilis, B. adolescentis or E. coli ConA-induced histamine release was diminished up to 25%, 71%, 58% and and 68% of maximal histamine release, respectively. Preincubation of rat mast cells with B. thetaioataomicron, B. fragilis, B. adolescentis or E. coli also changed their reactivity in anaphylactoid reaction with compound 48/80 (histamine release was diminished up to 70%, 63%, 63% and 60%, respectively).