Radiolabeling, extraction and characterization of surface antigens as illustrated by studies on Schistosoma mansoni

The most commonly used method for studying surface antigens involves direct radiolabelling with 125I. Several methods of iodination exploit a very simple chemical reaction, halogen substitution. The radiolabelling of Schistosoma mansoni adult worms serves as a prime example. Initial attempts to radiolabel surface antigens of adult worms by lactoperoxidase catalyzed iodination yielded equivocal results. Attempts to label living adult schistosomes with chloramine-T or diazotized iodosulfanilic acid yielded similar results. Satisfactory and reproducible radioiodination of tegumental proteins of living adult worms was finally achieved using the Bolton-Hunter reagent. Isolation of schistosome tegumental antigens has included extraction by freeze-thaw, saponin, saline, sodium dodecyl sulfate, deoxycholate, the non-ionic detergent Nonidet P-40, treatment with trypsin and incubation in phosphate buffered saline. The isolated fractions were membrane material