EFFECT OF BOVINE-MILK ANTIGENS AND EGG LYSOZYME ON THE BINDING OF FE-59-LACTOFERRIN TO PLATELET PLASMA-MEMBRANES

1. Platelets bind specifically to lactoferrin. A significant similarit y between human lactoferrin and some bovine milk proteins has been est ablished. 2. Because of the structural homology of lactoferrin and cow s milk proteins they are able to influence lactoferrins regulatory fun ction on the level of its binding to membrane receptors on platelets. 3. An inhibitory effect of bovine alpha-lactalbumin and of beta-lactog lobulin on lactoferrin-receptor interaction was shown. 4. Bovine alpha -lactalbumin competes with lactoferrin for the binding sites. 5. Scatc hard plot analysis of data shows one binding site for lactoferrin in t he presence of alpha-lactalbumin with an affinity constant, Ka=0.46x10 (9) mol/l and 335 receptors/cell. 6. The inhibitory effect of beta-lac toglobulin reaches 62% and is different for the common fraction beta-l actoglobulin and the genetic variants beta-lactoglobulin A and B. 7. b eta-lactoglobulin does not compete with lactoferrin for the membrane r eceptors. 8. Bovine casein and egg lysozyme stimulate Fe-59-lactoferri n binding to the receptors. The mechanism of these effects is still un known. 9. Tested alimentary antigens are able to interact with lactofe rrin and also with some platelet membrane structures. 10. Established changes in lactoferrin binding to the platelet membrane might be in re lation to lactoferrins regulatory function and (or) eliminating mechan isms of these alimentary antigens.