Skip to Main Content

The survival of red cells in the circulation can be measured in a variety of ways: (1) by labeling with isotopes, particularly 51Cr, and assessing the disappearance of the tag from the circulation over time; (2) by labeling the erythrocytes with biotin or fluorescent dye and measuring this marker over time; (3) by determining the disappearance of transfused allogeneic erythrocytes using immunologic markers; and (4) by measuring the excretion of carbon monoxide (CO), a product of heme catabolism.

Such studies show that normal human red cells have a finite life span averaging 120 days, with very little random destruction. During maturation of the reticulocyte, cell density increases, but after a few days of intravascular life span there is little further increase in density or other changes in the physical property of the red cells. Thus cell density is not a good marker for aged red cells. This has made the senescent changes in the red cell that mark it for destruction difficult to study. Candidates for such changes include changes in membrane band 3 and exposure of phosphatidylserine on the membrane, which may be of major importance.

Acronyms and Abbreviations

Acronyms and abbreviations that appear in this chapter include: ADP, adenosine diphosphate; AMP, adenosine monophosphate; C3, third component of complement; 14C, radioactive carbon; CO, carbon monoxide; 51Cr, chromium-51; 50Cr, chromium-50; DFP, diisopropylfluorophosphate; 55Fe or 59Fe, radioactive iron; G-6-PD, glucose-6-phosphate dehydrogenase; Ig, immunoglobulin; 111In, indium-111; 15N, nitrogen; PK, pyruvate kinase; 99mTc, technetium-99m.

Measurement of Red Cell Destruction

Red Cell Life Span

The original method for the measurement of the red cell life span consisted in the transfusion of cells that were compatible but identifiable immunologically—the Ashby technique; type O red cells were infused into individuals with type A or B cells and the recipients’ own cells were removed using anti-A or anti-B serum.1 During World War II and shortly after, this method was used extensively, but in recent years, because of the hazards associated with the administration of allogeneic erythrocytes, it has been completely replaced by techniques based on labeling of autologous blood.

In 1946, Shemin and Rittenberg demonstrated that the incorporation of nitrogen (15N)-labeled glycine into heme could be used to measure the life span of the red cells.2 Since then a number of other isotopic methods have been developed. These can be divided into three groups: (1) those that label a cohort of cells, (2) those that label cells randomly, and (3) those that use indirect measurements such as the rate of production of red cells or the rate of heme breakdown. The first two classes yield information about the nature of the shortening of the red cell life span, age-dependent or random. The last group yields only mean life span.

Cohort Methods

...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.