Abstract
When mice were orally administered with mature eggs of Toxocara canis (T. canis) (100 eggs/mouse), unique populations of hepatic T cells were induced during infection. On day 1 after administration, double-positive (DP) CD4=8= cells were transiently demonstrated in the liver. These DP cells were raely seen in the liver of control mice. Detailed characterization showed that they contained a unique population carrying the CD4+8a+b- phenotype. This raised the possiblity that they were generated extrathymically in the liver. On day 3 and day 7, the propotion and absolute number of extrathymic T cells expressing IL-2 receptor b-chain and CD3 of intermedicate levels (i.e., intermediate CD33 cells) were also elevated. During this early phase of infection, the thymus tended to become atrophic while the spleen remained unchaged in term of the number and the surface phenotype. The early phase of T. canis infeciton is known to be the time when hatched larvae go to the liver; they thereafter stay in liver or migrate to tissue. Therefore, these results suggest that a unique interaction between T. canis and host defence system occur in the liver during this intial time-period.
Key words: hepatic T cells; T. canis infection; double-positive cells; extrathymic T cells; liver; int TCR cells.