THE SURVIVAL OF INGESTED LACTOFERRIN IN THE GASTROINTESTINAL-TRACT OFADULT MICE

Lactoferrin is an 80 kDa major protein component of mammalian colostra l whey. The antimicrobial active centre of lactoferrin, lactoferricin (Lfcin), may also be an important determinant of the interaction betwe en lactoferrin and specific receptors on lymphocytes, We have document ed the survival in vivo of ingested lactoferrin in the gastrointestina l tract of adult mice by surface-enhanced laser desorption/ionization affinity MS. Various kinds of degraded lactoferrin fragments were dete cted as molecular-ion peaks corresponding to Lfcin after being capture d by an affinity capture device, hydrolysis in situ and laser desorpti on/ionization. No evident molecular-ion peaks of Lfcin were observed u pon analysis of faeces from mice fed commercial milk, whereas lactofer rin fragments containing the Lfcin region were detected at concentrati ons in the order of at least pmol/g in the faeces of mice fed milk enr iched with lactoferrin at 40 mg/ml. These results suggest that ingeste d lactoferrin would survive transit through the gastrointestinal tract as partially degraded forms containing the receptor-binding region(s) as well as the antimicrobial active centre.