Idiotypic modulation oftheantibody response ofmicetoEchinococcus granulosus antigens

SUMMARY Inthis workwe analysed themodulation oftheantibody responsetoEchinococcus granulosus antigens viaanti-idiotype (Ab2)administration. Ina first setofexperiments, we determined the antibody responsetohydatid cystfluid antigen (HCFA)ofmiceimmunized withAb2.Results showedthat Ab2elicited anti-HCFA antibodies inmicethathadneverbeenexposed toHCFA before. Moreover, that responsewas characterized bybooster effect, avidity maturation andan inverse correlation between avidity andAb2dose. Weinfected these miceandmeasured thetitre andavidity ofanti-HCFA antibodies during 250daysofinfection. Lackofavidity maturation was themostimportant feature observed, suggesting that theparasite (either protoscolex orcyst) could modulate theantibody responseofitshost. Ina second setofexperiments, we investigated the presenceofregulatory anti-idiotypes intheAb2preparation. Inthis context we treated neonates withdifferent doses ofAb2,immunized themwithHCFA 12weeks later anddetermined their antiHCFA titres. A specific andAb2dose-dependent suppression oftheresponsetoHCFA was observed, suggesting theexistence ofregulatory anti-idiotypes intheAb2preparation. Although this Ab2could beinvolved intheregulation oftheanti-HCFA response,other anti-idiotypes could also beinvolved. Ourresults showthat itmay bepossible toimprove theavidity oftheanti-HCFA responseviatheadministration oftheanti-idiotype Ab.However, theliveparasite could successfully revert this effect bymechanisms notyetcharacterized.