Developmental aspects of splenic function in sickle cell diseases

Abstract

In order to study developmental aspects of splenic function and dysfunction in children with Hb SS disease and other Hb S syndromes, red cells were examined by interference phase-contrast microscopy. In the youngest children studied (<1yr) the number of red blood cells bearing 'pocks' was low (<1%), the same as in normal eusplenic controls. In most children over 8 yr of age, >12% of the red blood cells were pocked, in similarity to what is observed in surgically asplenic individuals. Between 1 and 8 yr of age, many Hb SS children had intermediate numbers of pocked red blood cells, and that suggested hyposplenism. Young children with Hb As, S-ß thalassemia, and S-HPFH were found to have normal splenic function by this technique. Children with Hb SC disease had a moderate degree of splenic dysfunction. This technique correlates with Howell-Jolly body enumeration and99mTc spleen scans, but it is semiquantitative, and it appears to differentiate the transfusion-reversible 'functional' hyposplenism of childhood and the anatomic asplenia secondary to autosplenectomy of later life. Interference phase microscopic enumeration of red cell pocks is a useful and accurate way to assess the onset of splenic dysfunction, which identifies the time of increased susceptibility to overwhelming bacterial infections.