Iodinated soluble adult worm protein preparations of Schistosoma mansoni do not induce immediate hypersensitivity reactions but retain other immunogenic properties.

Samples of Schistosoma mansoni soluble adult worm proteins (SWAP) were iodinated with 4-15 mumol I/mg protein using iodine monochloride. The capacity to elicit immediate hypersensitivity reactions of the iodinated derivatives was compared to that of the native SWAP preparations. The degranulation of mast cells from infected mice decreased with increasing iodine incorporation and was absent in fully iodinated samples containing 15 mumol I/mg protein. The response of guinea pigs and humans to the intradermal test with iodinated SWAP also decreased in proportion to iodine incorporation, and no responses were obtained with fully iodinated samples. No false-positive tests were observed. Antibodies to the fully iodinated extracts generated in C57BL/10 mice reacted by ELISA with the unmodified proteins and by immunoprecipitation on agar gel. The immunoprecipitation pattern suggested that some epitopes were altered by iodination.