Acquired immunity to Fasciola hepatica in splenectomised rats.

Significant resistance to a second infection with Fasciola hepatica was obtained in splenectomised and sham operated rats (P less than 0.001, 78 and 76 per cent respectively) when compared with singly infected splenectomised or sham operated control groups. For both the stimulating and challenge infections, there were no significant differences in the number of flukes recovered from rats that had been splenectomised as compared to those receiving the sham operation. Thus, splenectomy did not significantly affect the ability of rats to develop an acquired immunity to F hepatica, nor were fluke recoveries from a particular schedule of infection significantly affected by the presence of absence of a spleen. It is concluded that the presence of a spleen is not necessary for the development of acquired immunity to F hepatica in the rat.