Amino Acid Accumulation by Human Reticulocytes

1. The concentrations of certain amino acids were measured by ion exchange chromatography in mature red cells, in red cells with a high percentage of reticulocytes, and in the plasma in which these red cells had been suspended. The concentration ratio as a measure of net accumulation of the red cells for amino acids was derived from these data.

2. Adult red cells can accumulate glycine and alanine, but not methionine, valine, isoleucine or leucine.

3. Reticulocytes can accumulate glycine best, then alanine, then methionine, isoleucine, and leucine to approximately the same extent. They were unable to maintain a concentration gradient for valine.

4. In two patients with thalassemia, no abnormality was found in the plasma or red cell levels of citrulline, proline, glycine, alanine, valine, isoleucine, tyrosine, or phenylalanine. In one of the thalassemic patients no abnormality of histidine was found. The amino acid accumulation by thalassemic, or fetal red cells was the same as for normal red cells of comparable reticulocyte percentage.