IMMUNOLOGICAL CROSS-REACTIVITY BETWEEN SCHISTOSOMA-MANSONI AND CHOLERA-TOXIN

Intranasal administration of schistosome antigens in combination with appropriate adjuvant may be an effective route for immunization agains t schistosomes, since the lungs represent an important site of elimina tion of schistosomulae. Our previous studies have shown that in mice i ntranasal administration of cholera toxin (CT) before infection with S chistosoma mansoni results in an enhancement of the worm burden in com parison to nontreated infected animals. In the present study, it was s hown that mice treated intranasally with CT displayed high numbers of schistosome-reactive IgM-secreting cells in the spleen as well as high levels of schistosome-reactive serum IgM antibodies, whereas no signi ficant immunological response against two other antigens, ovalbumin (O VA) or keyhole limpet haemocyanin (KLH) was noted. Sera from mice trea ted intranasally with CT recognized a 22 kDa antigen on SWAP blots. Th is band was not demonstrable after absorption of the sera with SWAP. T hese findings indicate a possible cross reactivity between cholera tox in and schistosome antigens. Further analysis by Western blot revealed that a 22 kDa antigen was detected on CT blots by sera from mice and humans infected with S. mansoni. This band was not demonstrable after absorption of the mouse or the human sera with CT. The 22 kDa cross re active antigen was heat-stable. The antibodies against the 22 kDa anti gen were only found within the IgM class but not within other Ig isoty pes. Our findings also indicate that the 22 kDa antigen detected by an ti-S. mansoni antibodies represents the A1 fragment of the cholera tox in.