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Interleukin‐12 modulates T‐cell responses to microfilariae but fails to abrogate interleukin‐5‐dependent immunity in a mouse model of onchocerciasis
Author(s) -
Hogarth P. J.,
Bianco A. E.
Publication year - 1999
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.1999.00891.x
Subject(s) - immunology , biology , priming (agriculture) , immunity , eosinophil , immune system , onchocerciasis , interleukin 5 , interleukin 4 , antigen , interleukin , antibody , cytokine , germination , asthma , botany
Summary Infection of mice with microfilariae of Onchocerca lienalis induces high levels of protective immunity to reinfection, which is dependent on interleukin (IL)‐5 but not IL‐4. Here, we have investigated the effect of exogenous IL‐12 administration during either the priming or effector phases of the immune response. When administered during priming, IL‐12 induced down‐regulation of parasite‐specific serum immunoglobulin (Ig)E and up‐regulation of IgG2a. Antigen‐specific IL‐4 responses were strongly suppressed, whilst blood eosinophil levels were partially reduced. When administered during a challenge infection, IL‐12 did not significantly influence the balance of antibody isotypes, but partially reduced eosinophil production. Antigen‐specific IL‐4 responses were again completely ablated. Unusually, interferon‐γ (IFN‐γ) responses were not significantly affected following IL‐12 administration, either during priming or after challenge infections. Moreover, despite a fall in antigen‐specific IL‐5 production, the expression of IL‐5‐dependent immunity, as determined by reduction in worm recoveries, was fully maintained. These data demonstrate that parasite‐induced IL‐4 can be abrogated without affecting protective immunity to Onchocerca microfilariae in mice. In view of the established role of IL‐4 in pathogenesis, this may have important implications for the development of immunoprophylaxis aimed at microfilariae and the alleviation of pathology in onchocerciasis.