Isolation of a Mast Cell Degranulating Polypeptide from Ascaris suis

Ascaris suis was extracted with 60% ethanolin dilute formic acid after previous removal of fat with organic solvents. After dialysis, the extract was further purified by ammonium sulphate precipitation, treatment with Amberlite IRC‐50 (XE‐64), chromatography on CM‐ cellulose and gel filtration on Sephadex G‐25. The purified product with a molecular weight probably within the range 2000–3000, had basic character with an isoelectric point ca 12.3 in 0.05 M borate buffer. It behaved as a nearly homogeneous compound on paper electrophoresis and on gel filtration. Nitrogen content: 16.7%. Fifteen amino acids were identified by paper chromatography after acid hydrolysis: alanine, arginine, cystine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tyrosine and valine. The purified product was degradrd and inactivated by the proteolytic enzymes papain, pronase, trypsin, α‐chymotrypsin and partially by pepsin. The polypeptide caused degranulation of rat mesentery mast cells, even such cells from germ free animals, indicating that the mast cell respome was the result of a direct action of the Ascaris principle on the mast cell and not due to an antigen antibody reaction.