Lactoferrin binding to human platelets.

1. Platelets bind specifically lactoferrin. 2. The lactoferrin binding to the platelets depends on the concentration of labelled lactoferrin, the number of platelets, the time of incubation and pH. 3. The binding was characterized by two types of binding site: one with high affinity and low capacity, and another with low affinity and high capacity (respectively Kaff1 = 13.6 x 10(9) l/mol and about 40 binding sites, and Kaff2 = 1.23 x 10(9) l/mol and about 135 binding sites per platelet). 4. Both human transferrin and bovine lactoferrin compete with human lactoferrin for the receptors. 5. The presence of lactoferrin receptors on the platelet membrane surface is connected most probably with the effect(s) on the cell function(s) of these cells.