Increased agglutinability by anti-i of red cells in sideroblastic and megaloblastic anaemia.

Abstract

Agglutinin titres have been performed using anti‐I and anti‐i cold antibodies on red cells from patients with sideroblastic, iron deficiency and megaloblastic anaemias, as well as on normal adult and cord blood red cells.Raised i antigen titres were found using the red cells of 13 of 15 patients with sideroblastic anaemia and of seven of eight patients with megaloblastic anaemia but in none of eight patients with iron deficiency anaemia and in one of 17 patients with megaloblastic anaemia in remission. Those patients who had an elevated i antigen titre usually also had an elevated I antigen titre.The raised i and I antigen titres of the red cells of a patient with pernicious anaemia were shown to decrease markedly within 3 months of the onset of B12 therapy, indicating that the alteration probably persists for the life‐span of the red cell but that the cause of the alteration is reversible once the underlying blood disorder is corrected.It is believed that disordered erythropoiesis results in membrane alterations which lead to the increased agglutinability, but the cause is not known. It does not appear that a shortened red cell maturation time is a necessary factor.