Preliminary characterization of anticomplementary components of hydatid cyst fluid

Sheep hydatid cyst fluid (SHCF) was fractionated on Sephacryl HR S-200 and the anticomplementary activity (alpha-C activity) determined in the fractions obtained; 67% of total alpha-C activity of SHCF was recovered in the void volume fraction (SHCF-I) which contained 61% of SHCF carbohydrates. The bulk of the activity of SHCF-I was eluted by FPLC chromatofocusing on Mono P HR at pH 5.9. After heating at 100 degrees C for 15 min, SHCF and SHCF-I conserved 74 and 54%, respectively of their alpha-C activity. In addition, 37 and 11% of SHCF and SHCF-I alpha-C activity, respectively bound to Protein A. Components not bound to Protein A (SHCFPA and SHCF-IPA) were fractionated on Con A-Sepharose; 71 and 65%, respectively of their total alpha-C activity was retained by this lectin indicating the presence of alpha-D mannoside and alpha-D glucoside residues in the active molecules. Our results suggest that SHCF could contain two classes of alpha-C components: immune complexes and thermoresistant molecules with high carbohydrate content.