Radioimmunoassay of cationic trypsin-like immunoreactivity in man.

The present paper describes the preparation of human cationic trypsin and of a stable and fully immunoreactive 125I-labelled tosyl-lysine chloromethyl ketone (TLCK) cationic trypsin by a modified chloramine-T method with a high specific radioactivity; the production of an avid and specific rabbit cationic trypsin antiserum; and a sensitive, precise, and specific radioimmunoassay method enabling measurements of fasting serum trypsin-like immunoreactivity (CTLI) in the low ng/ml range in normals; the significant rise in serum CTLI in patients with normal pancreatic exocrine secretion; and the absence of any rise in patients with severely reduced pancreatic exocrine secretion after intravenous injection of secretion; a markedly elevated fasting serum CTLI level in patients with acute pancreatitis; fasting CTLI in duodenal juice; and separation of CTLI in one minor and one major molecular component in fasting serum.