This may be because the surface antigens, A, B, and +, are dangle blobs on the surface of the blood cell, offering more surface area for antigens to attack: whereas O doesn't have A or B blobs, and the - groups don't have the + blob, therefore they have a smoother surface.
This may be because the surface antigens, A, B, and +, are dangle blobs on the surface of the blood cell, offering more surface area for antigens to attack: whereas O doesn't have A or B blobs, and the - groups don't have the + blob, therefore they have a smoother surface.