Method of assay of red cell folate activity and the value of the assay as a test for folate deficiency

作者：Allan Victor Hoffbrand, Beverley F. A. Newcombe, David L. Mollin · 发表于：Journal of Clinical Pathology · 年份：1966 · DOI：10.1136/jcp.19.1.17 · 被引用次数：327 · 研究领域：Digestive system and related health、Immunodeficiency and Autoimmune Disorders、Folate and B Vitamins Research

A simplified microbiological assay for determining the folate content of red cells is described. As in previously reported methods Lactobacillus casei is used as test organism but two modifications are introduced. First, haemolysis is carried out in water containing 1 g.% of ascorbic acid; secondly, haemolysates are not incubated before the assay. Using this assay, recovery of pteroylglutamic acid added in two different concentrations to five different whole blood samples was 97.0 +/- 1.9 S.E. % and 106.1 +/- 4.7 S.E. % respectively. The coefficient of variation of the assay was between 11.2 and 15.0%. Haemolysates were best stored deep frozen, showing no significant loss of L. casei activity for three to five months at -20 degrees C. On the other hand, non-haemolysed blood samples were best stored at 4 degrees C. when there was no loss of activity for seven to 10 days. Experiments confirmed that plasma is necessary for the maximum release of red cell L. casei activity, and showed that only small amounts of plasma are necessary; folate- and B(12)-deficient plasma released slightly lower L. casei activities from red cells than did normal plasma. The red cell folate levels of 40 healthy normal subjects ranged from 160 to 640 mmug. per ml. of packed red cells. One hundred and twenty patients with subnormal serum folate levels due to idiopathic steatorrhoea, nutritional folate deficiency and Crohn's disease, partial gastrectomy, myelosclerosis, and polycythaemia vera were studied...