K. Vehmeyer et al., LECTIN-INDUCED INCREASE IN CLONOGENIC GROWTH OF HEMATOPOIETIC PROGENITOR CELLS, European journal of haematology, 60(1), 1998, pp. 16-20
The galactoside-specific plant lectin, Viscum album agglutinin (VAA-I)
increases cellular parameters of natural host defence. It also binds
to a variety of haematopoietic cells, including progenitors. We invest
igated whether VAA-I has a stimulatory effect on haematopoietic progen
itor cells. Peripheral blood progenitor cells from 7 healthy volunteer
s were cultured in a colony assay with VAA-I plus erythropoietin (EPO)
and stem cell factor (SCF). At 50 pg/ml VAA-I induced a significant i
ncrease in the cytokine-dependent clonogenic growth (52% in median, p
< 0.05). In another set of experiments purified CD34(+) cells were iso
lated from the bone marrow aspirate of 4 patients with non-metastatic
breast cancer using fluorescence-activated cell sorting. Binding to CD
34(+) cells was demonstrated by using directly fluorescence-conjugated
VAA-I. Go-incubation with D-galactose significantly abrogated this ef
fect, CD34(+) cells were cultured in the presence of EPO, SCE interleu
kin-3, granulocyte/monocyte colony-stimulating factor and granulocyte
colony-stimulating factor. VAA-I alone had no measurable effect on the
clonogenic growth of the isolated cells. However, at concentrations o
f 100 and 250 pg/ml VAA-I increased the cytokine-dependent proliferati
on and differentiation of CD34(+) cells by a median of 75 and 85%, res
pectively. The results show that VAA-I binds to haematopoietic progeni
tor cells and has a co-stimulatory effect on their proliferation.