Immune reactions in mucous membranes. I. Intestinal mast cell response during helminth expulsion in the rat.

Measurement of the mast cell response in the jejunal mucosae of rats infected with was carried out at the time of worm expulsion (self-cure). Just prior to the start of self-cure, a new mast cell population differentiated from cells with large nuclei and prominent nucleoli. Beginning on the 10th day of infection, mast cell numbers increased in an exponential fashion and reached a peak in the middle of the self-cure reaction 14 days after infection. At first the cells had few granules but their granule content subsequently increased and by day 14 some of them appeared to be mature. Mitoses were observed in granulated cells at all stages of the population expansion. Differential counts showed that an increasing proportion of the mast cell population migrated intraepithelially to become globule leucocytes so that by day 14 the ratio of globule leucocytes to mast cells was 1/1. On subsequent days of infection, this ratio and the total population of granulated cells gradually diminished. The results suggest that cell differentiation and division are responsible for the population increase. The high globule leucocyte/mast cell ratio points to an extensive release of amines from the granules during self-cure. The significance of this reaction in relation to antibody release from the mucosa and to worm expulsion is discussed.