Recombinant human intelectin binds bovine lactoferrin and its peptides

Intelectin (IntL), a lectin that exists on the brush border membrane of the small intestine, plays a role in the innate immune response and also acts as a receptor for lactoferrin (LF), an iron-binding glycoprotein found in milk and other secretions. Similar to human LF (hLF), bovine LF (bLF) has been shown to induce proliferation and differentiation of human enterocytes and to modulate their cytokine productions. To evaluate the interaction between human IntL (hIntL) and bLF, recombinant hIntL (rhIntL) conjugated with a tag sequence was examined for its ligand-binding capacity by using microtiter plates coated with LF or other proteins. Interestingly, rhIntL showed higher binding for bLF than hLF. It also bound pepsin hydrolysate of bLF, but to a lower degree than native bLF. A very low binding of rhIntL was observed for bovine serum albumin or transferrin. These findings suggest that hIntL acts as a receptor for bLF and its digested fragments.