Rats subjected to prolonged macrophage depletion showed an increased prevalence of senescent RBC in the circulation due to their impaired clearance by macrophages. Hence, these animals provide a model system in which mechanisms of RBC aging can be delineated. They also showed impaired erythropoiesis, presumably related to a reduction in BM macrophages and increased production of proinflammatory cytokines by residual activated marrow macrophages and other cells.

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Haematological abnormalities because of Cl2MDP-CL-induced macrophage depletion are potentiated in aged rats in which the BM regenerative potential of the erythroid lineage as well as the clearance function of the spleen appear compromised. Thus, in aged rats, macrophage dysfunction is likely to interfere with erythroid homeostasis particularly during haemopoietic stress.

In the present study we examined five subjects affected by hereditary spherocytosis (three unsplenectomized and two splenectomized), coming from an area in the north‐east of Italy where hereditary spherocytosis is an anaemic disease with very low incidence. All patients showed a low degree of spectrin deficiency (14%), detected with sodium dodecyl sulfate polyacrylamide gel electrophoresis. Moreover, when this analysis was performed with N, N'‐diallyltartardiamide as cross‐linking agent instead of N, N'‐methylenbisacrylamide, some unusual bands appeared in the region between proteins 4.2 and 5, the three unsplenectomized and two splenectomized patients showing different patterns. We hypothesise that some alterations of proteins in this region (e.g. the 4.5 or 4.9 bands), possibly due to proteolysis, must have occurred in relation to the disease.