Cobalamin forms and analogues in plasma and myeloid cells during chronic myelogenous leukaemia related to clinical condition

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Abstract
Plasma and buffy coat specimens of CML patients with untreated disease, in chronic and accelerated phase, and in overt blastic crises were analysed for the cobalamin patterns using non-polar extraction, thin-layer chromatography and bioautography. Splenic tissue specimens from four splenectomized patients in accelerated phase were analysed similarly. Cellular extracts were separated into two compartments by adsorption to haptocorrin antibodies. Plasma concentrations of all cobalamin forms were increased in CML. The proportion of methylcobalamin was significantly lower than in a reference population, and a low plasma proportion of methylcobalamin was associated with a poor prognosis. Buffy coat cells and splenic tissue had a higher proportion of 5'-deoxyadenosylcobalamin and a lower proportion of methylcobalamin than plasma; still, there was relatively more methylcobalamin than in normal tissue. The haptocorrin-bound compartment differed from the non-haptocorrin compartment in untreated or chronic phase patients by binding less methylcobalamin. An estimate of cobalamin analogues in plasma was achieved by comparing two different isotope dilution assays employing a cobalamin-specific binder, intrinsic factor, and a nonspecific binder, hog non-intrinsic factor. Values for total cobalamin and analogues were increased to the same degree in CML plasma.