Alterations in size, shape and osmotic behaviour of red cells after splenectomy: a study of their age dependence

In whole blood from splenectomized subjects (n = 20), red cells showed a significant increase of mean surface area (MSA), mean cell volume (MCV), MSA/MCV-ratio and osmotic resistance, with the mean cell haemoglobin concentration (MCHC) being decreased. Studies on red cell populations of different cell age revealed that the increase of MSA affects younger and older cells, whereas the increase of MCV can mainly be ascribed to young cells with low density. The increased osmotic resistance is mainly determined by older cells due to a more favourable MSA/MCV-ratio. Shortly after splenectomy (n = 5) the MSA of younger and older cells increased, whereas the increase of MCV affected only young cells with a lowered density; moreover, the MSA/MCV-ratio increased in older cells in particular, resulting in a relatively greater increase of osmotic resistance. An impaired maturation of the reticulocyte may underlie the initial increase of MSA and MCV of young cells, but the present results contradict the current view that delayed maturation explains the changes in morphology and osmotic resistance of asplenic red cells.