Reduced Hexose Transport by Enterocytes Associated with Rapid, Noninjurious Rejection of Trichinella spiralis from Immune Rats

Abstract

Rats immunized against Trichinella spiralis rejected larvae from a challenge infection within minutes. Infectivity of these once-rejected larvae for nonimmune rats following intestine-to-intestine transfer, infectivity for nonimmune mice following oral inoculation, and normal development in these mice indicated that the parasite did not sustain immediate or long term damage as a result of the host's immune response. Associated with rapid worm rejection was a change in host intestinal function - altered absorption. Uptake of a hexose, 14C-beta-methyl-D-glucoside, was studied in intestinal segments isolated from rats before and 30 min after primary and secondary infections. Larvae were administered intraintestinally. Absorption was measured using a tissue accumulation method, under conditions of substrate saturation (30 mMolar) and over a 5-min period. 3H-mannitol was used as a marker to measure extracellular water, hence, extracellular sugar. Following challenge infection of previously infected (immunized) hosts, there was a significant reduction (22%; P less than 0.05) in hexose absorption as compared to the uptake rate before challenge. In contrast, cellular uptake before and 30 min after primary infection was similar. These findings are presented in support of the hypothesis that the failure of T. spiralis larvae to infect immune hosts is the result, not of direct worm damage, but of functional changes in gut epithelium, the habitat of the parasite.