Qualitative and quantitative analysis of erythrocyte surface membrane sialyl residues using affinity cytochemistry with special reference to diabetic patients.

Erythrocyte surface membrane sialyl residues were investigated by means of affinity cytochemistry using the avidin-biotin complex technique. Mild oxidation with the periodate (MO)-biotin hydrazide (BHZ)-ferritin avidin conjugate (FAv) sequence revealed numerous ferritin particles on erythrocytes from healthy donors. The ferritin particles attached on the perpendicularly sectioned membrane were seen at an average distance of 10 to 12 nm from the outer dense leaflet of the cell membrane. Pretreatment with neuraminidase followed by the MO-BHZ-FAv sequence almost eliminated erythrocyte ferritin labeling. Erythrocytes from diabetic patients showed less dense ferritin labeling compared with those from healthy donors. Quantiative analysis of sialyl residues demonstrated a marked reduction in ferritin labeling of erythrocytes from diabetic patients which was significantly less (p less than 0.01) than that of erythrocytes from healthy donors. This observation supports previous biochemical data demonstrating lower levels of surface membrane negative charge and sialyl residues on erythrocytes from patients with diabetes mellitus.