Mucosal T cells regulate Paneth and intermediate cell numbers in the smallintestine of T-spiralis-infected mice

Secretions of Paneth, intermediate and goblet cells have been implicated in innate intestinal host defense. We have investigated the role of T cells i n effecting alterations in small intestinal epithelial cell populations ind uced by infection with the nematode Trichinella spiralis. Small intestinal tissue sections from euthymic and athymic (nude) mice, and mice with combin ed deficiency in T-cell receptor beta and delta genes [TCR(beta/delta)(-/-) ] infected orally with T. spiralis larvae, were examined by electron micros copy and after histochemical and lineage-specific immunohistochemical stain ing. Compared with uninfected controls, Paneth and intermediate cell number s increased significantly in infected euthymic and nude mice but not infect ed TCR(beta/delta)(-/-) mice. Transfer of mesenteric lymph node cells befor e infection led to an increase in Paneth and intermediate cells in TCR(beta /delta)(-/-) mice. In infected euthymic mice, Paneth cells and intermediate cells expressed cryptdins (alpha -defensins) but not intestinal trefoil fa ctor (ITF), and goblet cells expressed ITF but not cryptdins. In conclusion , a unique, likely thymic-independent population of mucosal T cells modulat es innate small intestinal host defense in mice by increasing the number of Paneth and intermediate cells in response to T. spiralis infection.