Reduced red cell filtrability due to red cell plasma protein interactions

The adsorption of protein on red cell surface was studied by the measurement of protein in plasma and incubation of blood with 131I-albumin. The protein concentration of the moderately hypertonic plasma clearly decreased by the addition of red cells. The decay counts of 131I-albumin increased in the centrifuged red cell segment as the ionic strength in the plasma increased. For the interpretation of these results it was assumed that the human red cells suspended in plasma are covered with albumin under the normal ionic strength and adsorb more albumin molecules when the ionic strength in the plasma is elevated by the addition of NaCl. A multilayer adsorption of albumin is suggested at the ionic strength of 450 mOsmol. The excess adsorption of albumin on red cells reduces the filtrability of red cells through the nuclepore filter.