Humoral and cellular immune responses to Fasciola hepatica experimental primary and secondary infection in sheep.
Blood leukocyte changes, serum hepatic enzyme levels, lymphocyte proliferation in response to Concanavalin A (ConA) and to parasitic excretory-secretory products (FhESP), and antibody (IgG and IgM) responses (ELISA and Western blot) were studied in sheep, the natural susceptible host of F. hepatica, during the first 3 months of an experimental primary or secondary infection. The proportion of flukes established was similar in once- and twice-infected groups, but the flukes originating from the secondary infection migrated more rapidly to the bile ducts. Primary infection induced a marked peripheral eosinophilia from 3 to 13 weeks post-primary infection (PPIW). FhESP-specific IgM were produced from PPIW 2 with peaks in PPIW 3 and 9-10; FhESP-specific IgG increased from PPIW 2 to 6 and became stable afterwards. Western blotting revealed 12 major antigenic fractions in FhESP from 12, 15, 20, 24, 27, 28.5, 30, 41, 51, 56, 69 and 156 kDa; some non-specific ones have been characterized. A sequential recognition of higher then lower molecular weight antigens was observed. FhESP-specific lymphocyte proliferation was marked from PPIW 2 to 5. In contrast, ConA stimulation of lymphocytes was decreased. After secondary infection in PPIW 6, immune responses were modified. The ConA-induced lymphocyte proliferation was transitorily increased. In contrast, the humoral response, in particular against the early recognized antigens, and the level and the duration of the FhESP-specific lymphocyte proliferative response, were reduced.
Chauvin
A
A
Laboratoire de Parasitologie, Maladies Parasitaires, Ecole Nationale Vétérinaire, Nantes, France.
Bouvet
G
G
Boulard
C
C
D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood*; D015153:Blotting, Western; D003208:Concanavalin A / Q000494:pharmacology; D005211:Fascioliasis / Q000276:immunology*; D005260:Female; D005969:Glutamate Dehydrogenase / Q000097:blood; D005982:Glutathione Transferase / Q000097:blood; D007111:Immunity, Cellular; D007962:Leukocytes / Q000276:immunology; D008099:Liver / Q000469:parasitology / Q000503:physiopathology; D008297:Male; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology* / Q000469:parasitology
D000909:Antibodies, Helminth; D003208:Concanavalin A; D005969:Glutamate Dehydrogenase; D005982:Glutathione Transferase