IMMUNOSUPPRESSIVE PROTEINS SECRETED BY THE GASTROINTESTINAL NEMATODE PARASITE HELIGMOSOMOIDES-POLYGYRUS

Experiments are described in which the conditions for the production, assay and isolation of immunomodulatory factors from the excretory-sec retory (ES) products of Heligmosomoides polygyrus have been standardiz ed. For the inhibition of an in vitro antibody response to keyhole lim pet haemocyanin, immunosuppressive activity was most reproducibly prod uced by 10-20-day-old adult worms maintained in culture for 24 h. This activity was relatively stable at room temperature, at 50-degrees-C a nd pH 2, but was destroyed by boiling. Immunosuppressive activity was eluted from Sephadex G-100 in fractions preceding those containing the bulk of ES proteins, and resolved on sodium dodecyl sulphate-polyacry lamide gel electrophoresis with molecular masses of 67, 54 and 20 kDa. The relative purity of these factors was confirmed by iso-electric fo cusing, where immunosuppressive activity was associated with proteins of pI values of approximately 4.2 and 4.35.