Detection of methionine in pernicious anemia megaloblasts and other types of erythroid precursors.

Utilizing a bacterial-agar overlay technic incorporating the methionine-requiring bacterium Leukonostoc mesenteroides, little or no bacterial growth was seen surrounding the megaloblasts and proerythroblasts of eight patients who had severe untreated pernicious anemia. Similarly, scant bacterial growth was observed in five cases of chronic erythremic myelosis (DiGuglielmo syndrome). Heavy bacterial growth, indicating ample amounts of methionine, was seen in two cases of autoimmune hemolytic anemia, and in two cases of severe untreated folate-deficiency anemia. The results are consistent with the "methyltetrahydrofolate trap" hypothesis in pernicious anemia, in which a defect in the methylcobalamin-dependent methyltransferase leads to reduced amounts of methionine. These studies also suggest that a similar methyltransferase defect does not occur in folate deficiency or autoimmune hemolytic anemia. The generation of methionine, as estimated by the present technic, may also be defective in chronic erythremic myelosis.