Altered Erythropoiesis during the Course of Virulent Murine Malaria 1

Summary

Peripheral, medullary, and splenic erythroid parameters were quantitatively assessed in mice during the course of virulent malarial (P. berghei) infection. Mice became progressively anemic, with circulating erythrocytes, hematocrit, and hemoglobin levels declining to approximately 20% of control by Day 21. The anemia was further characterized by a 34% increase in mean corpuscular volume, a 16% elevation in mean corpuscular hemoglobin, and a 14% decrease in mean corpuscular hemoglobin concentration by Day 21. A meager 1.5-fold reticulocytosis was noted on Day 7, which declined thereafter. Tibial nucleated cellularity was depressed to 85 and 72% of control values on Days 7 and 21, respectively, while erythroid precursor numbers remained at 74% of control levels throughout the course of infection. In contrast, splenic nucleated cells were elevated 2-fold on Day 7 and increased approximately 4-fold on Days 14 and 21. Although nearly 20-fold elevations in erythroid precursor levels were apparent, these increases were below what one might expect in noninfected mice with a similar degree of anemia.

These data support the contention that the erythropoietic capability of mice infected with malaria is impaired. Accordingly, it is suggested that this situation contributes to the severe anemic status of malarial mice, in addition to the well-documented mechanisms leading to the destruction of parasitized and nonparasitized erythrocytes.

The research participation of P. Desrochers, R. Gundersen, M. Hardy, M. Haviland, D. Lynch, S. McGinnis, and M. Parlee is greatly appreciated.