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Schistosoma mansoni in Mice: the Pattern of Primary Cercarial Exposure Determines Whether a Secondary Infection Post‐chemotherapy Elicits a T Helper 1‐ or a T Helper 2‐Associated Immune Response
Author(s) -
Idle O. Farah,
MajBritt Johansson,
Karin Lovgren-Bengtson,
Jann Hau
Publication year - 2000
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1046/j.1365-3083.2000.00667.x
Subject(s) - schistosoma mansoni , biology , splenocyte , immunology , immune system , immunoglobulin e , schistosomiasis , antigen , praziquantel , antibody , cytokine , interleukin 4 , helminthiasis , helminths
Reinfection with Schistosoma mansoni following chemotherapy often results in an ameliorated granulomatous reaction and hence a mild disease. This study examined some of the immunological mechanisms that could be associated with this residual protection. BALB/c mice were infected with either a single dose (group A) of 100 S. mansoni cercariae or with 10 doses of 10 cercariae each (group B) given at 3‐day intervals. The mice were treated with praziquantel 8 weeks postinfection and, 2 weeks later, together with another group of naive mice (group C), they were infected with a single dose of 100 cercariae each. All the animals were killed 8 weeks later and schistosome egg antigen (SEA)‐ and soluble adult worm antigen preparation (SWAP)‐induced cytokine recall responses in splenocytes, as well as serum immunoglobulin levels, were quantified and hepatic granuloma sizes measured. Group A animals had higher levels of SEA‐induced interferon‐γ (IFN‐γ) but lower levels of interleukin (IL)‐5 than groups B and C ( P < 0.01). Group B animals had low SEA‐induced IFN‐γ levels and elevated IL‐5 levels, although these were lower than group C. SEA‐induced IL‐10 was low in both groups A and B as compared to group C ( P < 0.01). SWAP was less effective as an inducer of splenocyte cytokine production than SEA but both SWAP‐induced IFN‐γ and IL‐5 were detected in groups A and C. SEA‐ and SWAP‐specific immunoglobulin E (IgE) and immunoglobulin G (IgG) titres were not significantly different between the three groups. Granuloma diameters were larger in group C (mean 297 ± 51.3 μm) as compared to groups A (174 ± 49 μm, P < 0.01) and B (247.5 ± 44 μm, P < 0.05). Taken together, these results demonstrate that granuloma size is reduced during a reinfection exposure compared with a primary infection. This reduction is associated with a T helper 1 response in mice exposed to a single large dose of cercariae in the primary infection and with a predominantly T helper 2 response in those infected with multiple small doses.