[Decreased flexibility of newborn infant erythrocytes]

The rheological properties of erythrocytes of 10 full-term infants were studied. A method of filtration and measurements of viscosity of erythrocyte suspensions with a hematocrit of 80% were used. Erythrocytes of newborn infants were less flexible than erythrocytes of healthy adults. Rigidity of erthrocytes was due to an increased hemoglobin content of the erythrocyte membranes which was measured in isolated ghosts. After incubation of the cells with acetylphenylhydrazin Heinz-bodies were formed in the erthrocytes of adults. The flexiblity of these cells decreased markedly. More Heinz-bodies were found in the erythrocytes on the newborn infants, when their cells were incubated under identical conditions. These erythrocytes became more rigid than the erythrocytes of adults. From these results we conclude that the more rigid erythrocytes of the newborn infants would not pass the splenic sinus, especially when they contain Heinz-bodies. The rheological properties of the erythrocytes of newborn infants explain the shortened life-span of red cells of newborn infants.