Studies on the Mechanism of Phagocytosis Ii. Analysis of the Adhesion Phase E-iti Yokomura*, Yoriko Shimizu and Satimaru Seno

To clarify whether electrostatic interaction contributes, the adhesion of red blood cells to monocytes, the first phase of phagocytosis, was studied in vitro in ion-deficient environments comparing with that in ionic environments. Monocytes from mouse tumor ascites and chicken and mouse red cells were used. In isotonic sucrose aqueous solution, glutaraldehyde-fixed red cells did not adhere to monocytes, whereas in Hanks' solution, they did so. In •g Hanks•h solution adjusted to pH 5.8 or 6.95, the fixed red cells adhered to monocytes to the same degree as in Hanks' solution, but not in sucrose solution of pH 5.8, 6.95 or 7.4. Addition of calcium and magnesium ions to the isotonic sucrose solution to the same concentration as those in Hanks' solution did not induce adhesion of the red cells to monocytes. The percentage of monocytes being adhered to the fixed red cells to the total increased in direct proportion to the logarithm of the ionic strength in mixtures of Hanks' solution and isotonic sucrose aqueous solution at various ratios. The red cells fixed with glutaraldehyde and further methylated adhered to monocytes even in ion-free sucrose solution, but the fixed, deaminated red cells did not. From these results the mechanism of the adhesion was discussed from the viewpoint of lyophobic mechanism. In adhesion of the glutaraldehyde-fixed red cells to monocytes, Van der Waals' interaction may act between the cell surfaces in a short range and electrostatic interaction in a long range. On the other hand, the fixed, methylated red cells may adhere to monocytes by electrostatic interaction in ion-free sucrose solution.