Coating in vitro of erythrocytes with Tamm Horsfall-protein

A method is described to coat isolated peripheral blood erythrocytes in vitro with Tamm-Horsfall Protein (THP, uromodulin). Coating of erythrocytes with THP was accomplished by incubation of the cells in the presence of THP, made monomeric by incubation in a high urea concentration. THP-coating of erythrocytes was dependent on the THP-concentration, maximal coating being obtained at a protein concentration > or = 250 mg/ml. The best coating results were obtained if, during the co-incubation of erythrocytes with THP, urea was removed while the sodium chloride concentration was increased up to a physiologic concentration by means of dialysis. This alteration in chemical conditions promotes THP-polymerisation. Erythrocytes coated in this way could be preserved for at least 5 weeks in preserving solution, making them an interesting source of testing and control material. Coating of erythrocytes with THP could also be accomplished under conditions in which THP was preserved in a monomeric form, which suggests that peripheral blood erythrocytes having binding-sites for THP.