Ferritin as a surface marker for immunoscanning electron microscopy. observation of individual ferritin particles on...

This paper comprises a part of our study to examine whether ferritin can be used as an immunological surface marker for high resolution scanning electron microscopy. In the first part of the study individual ferritin particles in a sample of purified ferritin were demonstrated as spheres with a diameter of about 170 A by use of fixation by glutaraldehyde and thin coating by ion sputtering. In the second part of this study, ferritin particles as indicating the antigen sites of blood group A were also recognized on the erythrocytes by the same techniques as in the first part. Ferritin deposition differed in amount among the erythrocytes, but without regard to the shape of the cells. On the individual erythrocytes, heavier depositions tended to occur in the concavity of the cell. In conclusion, ferritin is useful as a surface marker in immunoscanning electron microscopy. It has the benefit, in comparison with the other markers hitherto reported, of allowing us to observe the fine features of the cell surface under immunological reaction.