Tippett and Sanger1, in their investigation of 18 anti-D sera produced by D-positive individuals, commented as follows with respect to the sera of two white CDe/cde (R1r) patients: “Two ‘anti-D’ stand apart for they do not react by the anti-globulin method, and more strange, they can be absorbed by dd cells. This latter peculiarity is somewhat reminiscent of the ‘anti-D’ made by guinea pigs injected with heat extracts of dd cells”. No elution investigations were reported.