Variable generation of specific acquired resistance in CBA/Ca mice chronically infected with schistosomiasis mansoni.
Naive CBA/Ca mice and CBA/Ca mice infected 12 weeks previously with 20 normal cercariae of Schistosoma mansoni were challenged percutaneously with isotopically labelled parasites. Challenge worm migration was followed, in 5 separate experiments, by means of compressed organ autoradiography. In three experiments, 43.1% of challenge parasites did not arrive in the lungs of infected mice on day 6 as compared to 7.7% in naive controls, thereby indicating that pre-lung sites constitute the first barrier in resistance to reinfection. A further 15% of the challenge worm burden was lost in the lungs or en route to the liver in the immune animals, and portal perfusion revealed that 25.4% of the challenge was lost in the liver. Two other experiments revealed no comparable phases of pre-liver attrition however; instead resistance was only evident at final perfusion on days 28 or 35. These data reveal the variable generation of specific acquired immunity in mice harbouring a chronic schistosome infection and thus clarify current discrepancies in the literature. The results are discussed in relation to documented evidence for the nature of specific and non-specific immune mechanisms reported to operate at different sites in the infection model of schistosomiasis mansoni.
Delgado
V S
VS
Division of Parasitology, National Institute for Medical Research, Mill Hill, London.
McLaren
D J
DJ
D000818:Animals; D002908:Chronic Disease; D005260:Female; D008099:Liver / Q000469:parasitology; D008168:Lung / Q000469:parasitology; D051379:Mice; D008808:Mice, Inbred CBA; D012555:Schistosomiasis mansoni / Q000276:immunology*