Ultrastructural changes in human erythrocytes caused by heat and the localization of ABO blood group activity

The ultrastructural changes in human erythrocytes caused by heat and the localization of ABO blood group activity have been studied electron microscopically. Osmotically hemolyzed cells were found to show varying degrees of cell matrix loss and a swelling of the membranes. By means of immunoferritin staining, ferritin particles, which indicate the localization of ABO group activity, were found to bind in clusters on small process-like structures on the membranes. Erythrocytes heated to 60 degrees C showed a hemolytic change; the cell matrix was released and small globular substances (ca. 50-100 nm in diameter) aggregated on the cytoplasmic side of the partially swollen cell membranes, a phenomenon that was not noted in erythrocytes that undergo a hypo-osmotic change. Erythrocytes heated to 100 degrees C underwent fragmentation, though the cell matrix was almost preserved and aggregated substances of varying size were noted inside the membranes. ABO group activity was demonstrated almost evenly on the sub-membrane aggregated substances and on the surface of the thermo-changed erythrocytes.