Blood group A antigen site distribution and immunoglobulin binding in relation to red cell age

Heterogeneity of alpha antigen site density was demonstrated on individual human A1 and A2 type red cells by immunoelectronmicroscopy using haemocyanin-conjugated antiglobulin. Examination of red cells fractionated on a Percoll density gradient showed that the heterogeneity was not age-related. The presence of autologous immunoglobulin on senescent red cells was also confirmed by the same technique.