EARLY INCREASE OF GUT INTRAEPITHELIAL MAST-CELL PRECURSORS FOLLOWING STRONGYLOIDES VENEZUELENSIS INFECTION IN MICE

The time-course of differentiation/proliferation of mast cells in gut epithelium was investigated in mice infected with the nematode Strongy loides venezuelensis. After infection, expression of proliferating cel l nuclear antigen increased in gut intraepithelial mast cells on days 7 to 11, followed by an increase in the number of intraepithelial mast cells from days 11 to 14. Mast cell precursors were defined as cells that formed mast cell colonies in methylcellulose culture. After infec tion, the numbers of mast cell precursors in the population of gut int raepithelial mononuclear cells (IEMNC) increased significantly on day 3 and returned to the pre-infection level by day 7. Mast cell precurso rs in Peyer's patches, mesenteric lymph nodes (MLN), and spleen also i ncreased from day 7 p.i. Production of IL-3 and IL-4 in MLN and spleen were increased between 7 and 11 days p.i. These results show that mur ine intestinal mastocytosis is initiated by an early increase in mast cell precursor number in the gut epithelium followed by proliferation/ differentiation of mast cells. Mast cell precursor numbers increased e ven before the production of IL-3 and IL-4 in MLN and spleen, suggesti ng that some local factors might be involved in this phenomenon.