1. Studies of splenic function were carried out on patients with sickle-cell diseases by the measurement of the clearance of autologous heat-damaged 99mTc-labelled erythrocytes from circulation and into the spleen, the spleen area by a scintillation scanning, the enumeration of pitted erythrocytes by direct-interference microscopy, and the percentage of irreversibly sickled cells (ISC) and of cells with Howell-Jolly bodies. All measurements were performed in seven HbS homozygotes, 10 patients with sickle cell β°-thalassaemia (S/β°-thalassaemia), three patients with sickle-cell disease (SC), four AS heterozygotes and 17 controls.
2. Three different patterns of splenic function were observed among the 20 patients with symptomatic sickle-cell diseases: six patients had enlarged hyperactive spleens, four had enlarged hypoactive spleens, and in 10 patients no splenic activity was detected.
3. The percentage of ISC was higher in sickle-cell anaemia than in S/β°-thalassaemia and very low in SC patients.
4. These results would suggest that the spleen goes through similar successive functional stages in the sickle-cell diseases, namely enlargement in the early years of life, which is followed by hypo-activity and finally atrophy. This evolution seems to be faster in sickle-cell anaemia than in S/β°-thalassaemia and SC disease.