Synthetic Red Blood Cell-Specific Glycolytic Intermediate 2,3-Diphosphoglycerate (2,3-DPG) Inhibits Plasmodium falciparum Development In Vitro.

Mechanisms of malaria parasite interaction with its host red blood cell may provide potential targets for new antimalarial approaches. Pyruvate kinase deficiency has been associated with resistance to malaria in both experimental models and population studies. Two of the major pyruvate kinase deficient-cell disorders are the decrease in ATP and the increase in 2,3-biphosphoglycerate (2,3-BPG) concentration. High levels of this metabolite, only present in mammalian red blood cell, has an inhibitory effect on glycolysis and we hypothesized that its accumulation may also be harmful to the parasite and be involved in the mechanism of protection provided by that enzymopathy. We examined the effect of a synthetic form, 2,3-DPG, on the Plasmodium falciparum intraerythrocytic developmental cycle in vitro. Results showed an impairment of parasite growth with a direct effect on parasite maturation as significant lower progeny emerged from parasites that were submitted to 2,3-DPG. Further, adding the compound to the culture medium did not result in any effect on the host cell, but instead the metabolic profile of an infected cell became closer to that of a non-infected cell.

Reticulocyte parameters in hemoglobinopathies and iron deficiency anemia

Flow cytometric reticulocyte analysis allows the evaluation of reticulocyte maturity. New reticulocyte parameters have been used in the diagnosis and management of anemias, in the bone marrow transplant setting and in the monitoring of iron replacement or erythropoiet in therapy. Reticulocyte numbers and maturation levels have been studied in different hemoglobinopathies and the results have been correlated with the degree of ineffective erythropoiesis. In order to verify differences in reticulocyte parameters in various types of anemias and to test the absolute number of immature reticulocytes as a possible discriminating factor among various types of anemias, reticulocyte counts were performed on 219 samples from patients with sickle cell anemia (SS) (n= 62), hemoglobin S trait (n=9), Sbeta thalassemia (n=7), hemoglobin SC disease (n=11), beta thalassemia trait (n=33) and iron deficiency anemia (n= 47), and non-anemic individuals (n= 50). Mean fluorescence index (MFI) was defined as representative of the degree of reticulocyte immaturity and it was evaluated as a percentage and in absolute values. Reticulocyte counts and MFI values were significantly higher in SS, Sbeta thalassemic and SC groups when compared to controls, but not different among the three anemia groups. Patients with hemoglobin S trait, iron deficiency anemia and beta thalassemia trait showed reticulocyte parameters similar to the non-anemic group. There was no difference between the b thalassemic trait and iron deficiency anemia in relation to any parameters. MFI in absolute numbers were significantly higher in anemias that develop with the hemolytic process, although this was not evident in MFI percentage values. Our results showed that the erythoid expansion in sickle cell diseases (SS, SC and Sb thalassemia) leads to an enhanced immature reticulocyte release from bone marrow and that the phenomena is more evident by the MFI counting in absolute figures than in percentages. We concluded that the assessment of reticulocyte maturity provides interesting data about the pathophysiology and erythopoietic response in different types of anemias