Comparative analysis of methotrexate polyglutamates in lymphoblast preparations from bone marrow and blood, and the contribution of residual red blood cells.
OBJECTIVE
Blasts isolated from bone marrow aspirates or blood samples of patients with acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML) were compared for uptake of methotrexate (MTX) and formation of MTX polyglutamates (MTX-Glu(n)). Red blood cells (RBC) from the same patient samples were also analyzed.


METHODS
Blasts were isolated by standard density centrifugation. RBC were prepared from the pellet of the same centrifugation. MTX-Glu(n) were analyzed by means of HPLC and radiochemical quantification.


RESULTS
In lymphoblasts isolated from blood, the distribution patterns of MTX-Glu(n) were the same as in bone marrow lymphoblasts, but the total amount of MTX-Glu(n) accumulated in blood lymphoblasts was reduced by 41% 51% when compared to the same number of bone marrow lymphoblasts of the same patient. RBC accumulated MTX but no formation of MTX-Glu(n) occurred.


CONCLUSIONS
The determination of MTX and MTX-Glu(n) in lymphoblasts isolated from blood samples of patients with common ALL provides qualitative information on the capacity of the blasts to form MTX-Glu(n) since distribution patterns of MTX and MTX-Glu(n) parallel that of bone marrow lymphoblasts. The amounts of MTX-Glu(n) accumulated, however, were much lower in blood lymphoblasts. Blood lymphoblasts are therefore not useful for a quantitative analysis of MTX-Glu(n). The contribution of RBC to MTX and MTX-Glu(n) in vitro is only marginal and residual RBC in lymphoblast preparations from bone marrow can therefore be ignored.
German Cancer Research Center, Heidelberg, Germany. m.weigand@dkfz-heidelberg.de
M
M
Weigand
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E
Frei
N
N
Graf
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M
Wiessler
D000293:Adolescent; D000964:Antimetabolites, Antineoplastic / Q000378:metabolism*; D001853:Bone Marrow / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000097:blood / Q000378:metabolism*; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008727:Methotrexate / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism*; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000097:blood / Q000378:metabolism*; D013997:Time Factors
D000964:Antimetabolites, Antineoplastic; D011099:Polyglutamic Acid; C014085:methotrexate polyglutamate; D008727:Methotrexate