Mast Cells and Macromolecular Leak in Intestinal Immunological Reactions.

The onset of the exponential expulsion of Nippostrongylus brasiliensis worms in the rat is associated with a sharp burst of intestinal mast cell activity and increased permeability of the bowel wall. It was found that the onset of maximum velocity of worm expulsion occurred earlier in female rats than in male rats and proceeded at a faster rate. There was a corresponding difference in the timing of the mast cell rise and macromolecular leak between the sexes. This suggested that there is a relationship between these events. Cortisone, a drug known to stop worm expulsion and to suppress the mast cell response, also prevented the macromolecular leak. Electron microscopy showed that during the period of increased permeability a pathway for protein tracers had opened up between the epithelial cells and it is suggested that this is the route for enhanced antibody transfer across mucous membranes. We suggest that a stimulus or stimuli from the parasite cause synchronous development of new populations of mast cells, IgE-producing plasma cells and plasma cells synthesizing antibodies of other classes possessing an anti-worm effect. It is also suggested that these mast cells discharge their pharmacological mediators by an allergen-reaginic antibody mediated system and that these mediators create a pathway through the intestinal mucosa for the translocation of antibody. [ABSTRACT FROM AUTHOR]