Fructose 2,6-bisphosphate in human erythrocytes

The fructose 2,6-bisphosphate concentrations in unwashed, washed, and leukocyte-free erythrocytes were compared. The concentration in washed red cells was 31 +/- 15 pmol per ml of cells (mean +/- S.D., n = 6). The concentration in unwashed erythrocytes was at least twofold higher, but the value in washed red cells was not due to leukocyte contamination because it did not decrease further when washed cells were passed through an Imgard column, which would have removed any remaining leukocytes. No platelets were detected among the washed erythrocytes. Thus, the concentration in erythrocytes after washing was ascribed solely to these cells. The fructose 2,6-bisphosphate concentration did not change when the glycolytic activity varied with pH, indicating that this compound is not involved in the regulation of carbohydrate metabolism in erythrocytes under these conditions.