Pathologic features associated with decreased longevity of mutant sphha/sphha mice with chronic hemolytic anemia: similarities to sequelae of sickle cell anemia in humans.

A colony of sphha/sphha mice with congenital hemolytic anemia and an abnormality in erythrocyte spectrin assembly was screened to determine the cause of premature death. Sphha/sphha mice have decreased life span, with 50% of animals dying by 6 months of age. The phenotype of these mutant mice includes moderate anemia (hematocrit: 21 to 28%), reticulocytosis, leukocytosis, lymphocytosis, extensive extramedullary hematopoiesis in spleen and liver, lymph node hyperplasia and membranoproliferative glomerulonephritis. With increased surveillance of this mouse colony, 20 clinically sick anemic mice were evaluated (complete blood counts and cultures of blood), euthanized and necropsied. Compared with anemic mice without clinical signs of disease, sick anemic mice had significantly higher white blood cell counts with only 4 (20%) of 20 animals being severely anemic (hematocrit: 4 to 8%). Blood from 11 (45%) of 20 animals was culture-positive for Pasteurella pneumotropica, Enterococcus, and/or Escherichia coli. In addition to the usual lesions in sphha/sphha mice, sick anemic mice had pneumonitis (95%) with thrombosis and infarction (80%) of one or more organs (spleen, myocardium, pancreas, liver, or bone marrow). The thrombotic tendency that accompanies the chronic hemolytic anemia in sphha/sphha mice, as well as the other clinicopathologic changes in these mutant mice, bears a striking resemblance to some poorly understood sequelae in human patients with sickle cell anemia. This mouse model may be useful in studying the pathophysiology of complications associated with sickle cell anemia in humans.