POLYCLONAL B-CELL ACTIVATION BY NEISSERIA-MENINGITIDIS CAPSULAR POLYSACCHARIDES ELICIT ANTIBODIES PROTECTIVE AGAINST TRYPANOSOMA-CRUZI INFECTION IN-VITRO

A hyperimmune rabbit antiserum against group C Neisseria meningitidis agglutinated and lysed Trypanosoma cruzi metacyclic trypomastigotes in a complement-mediated reaction. Immunization of rabbits with the puri fied polysaccharide C from N. meningitidis and of human volunteers wit h the AC-polysaccharide vaccine against meningitis also resulted in an tibody production cross-reactive with T. cruzi infective forms, The ra bbit antibodies bound to parasites, lysed metacyclic forms, and recogn ized several components from lysates of cell-derived trypomastigotes. The sera from six human volunteers reacted with cell-cultured trypomas tigotes in vitro, lysed these forms, and recognized glycoconjugates mi grating diffusely on the top of immunoblots. One serum also reacted wi th the isolated mucin-like glycoconjugate carrying the Ssp-3 epitope f rom cell-derived trypomastigotes, but treatment with sialidase did not abolish this reactivity. The anti-AC human antiserum also protected a gainst HeLa cell infection and markedly decreased the number of parasi tes liberated after cell burst. The polyclonal response that resulted from human immunization with N. meningitidis polysaccharides A and C c omprised trypanolytic antibodies that recognized nonsialylated epitope s expressed on infective forms of the parasite. It is suggested that h uman AC vaccination could be potentially helpful as an adjuvant to a s pecific immunotherapy of Chagas disease, developed with native or reco mbinant antigens of the parasite. (C) 1996 Wiley-Liss, Inc.