Erythrocyte age-dependent changes of membrane protein 4.1: studies in transient erythroblastopenia.

In high resolution sodium dodecyl sulfate-gel electrophoresis, the red cell protein, band 4.1, separates into a and b forms, which are closely sequence related polypeptides. In membranes from patients with hemolytic anemia, the relative amount of band 4.1b is increased, which has led to a suggestion that the relative proportion of these two 4.1 forms might be age dependent (Sauberman N, Fortier NL, Fairbanks GF, O'Connor RJ, Snyder LM 1979 Biochim Biophys Acta 556:292-313). We have measured the relative proportions of bands 4.1a and b in the red cells of seven patients with transient erythroblastopenia of childhood. In this disease, temporary cessation of erythroid cell production occurs, and the circulating red cells represent an aged cohort of erythrocytes. At diagnosis, the band 4.1 of red cell membranes was nearly entirely in the a form, and as reticulocyte levels rose during recovery, the predominant form became 4.1b. After recovery, the a/b ratio returned to normal. A transient period of moderate reticulocytosis and high levels of 4.1a could be detected in some cases, presumably marking the beginning of the recovery phase. These results support the proposal that the 4.1 band ratio is an internal marker of cell age in the human erythrocyte.