What can cause mixed-field agglutination?

There are multiple causes of mixed-field agglutination. They include:

  • blood transfusion
  • bone marrow transplantation
  • weak subgroups of A such as A3
  • polyagglutination due to T activation
  • altered expression of antigens due to disease (e.g., weakened A phenomenon)
  • anti-Lua
  • anti-Sda
  • twin chimerism (very rare)