U. Paulus et al., PURGING PERIPHERAL-BLOOD PROGENITOR-CELL GRAFTS FROM LYMPHOMA-CELLS -QUANTITATIVE COMPARISON OF IMMUNOMAGNETIC CD34(+) SELECTION SYSTEMS, Stem cells, 15(4), 1997, pp. 297-304
Autologous peripheral blood progenitor cell (PBPC) transplantation is
increasingly being used for treatment of indolent lymphomas, Since inv
olvement of bone marrow and peripheral blood is frequent and methods t
o reduce the lymphoma cell load of PBPC grafts are thus highly desirab
le, we have studied purging of PBPC comparing two immunomagnetic CD34(
+) selection systems (VarioMACS(TM), Miltenyi Biotech; Bergisch Gladba
ch, Germany, and Isolex50(TM) System, Baxter; Irvine, CA), Samples of
freshly collected mobilized PBPCs were contaminated with BALM-3 or KAR
PAS422 lymphoma cells that had been labeled with the fluorescent DNA s
tain Hoechst 33342., The mixture was subjected to separation with the
two devices and the resulting ''CD34(+)'' fractions were screened for
lyphoma cells by limiting dilution using fluorescence microscopy and b
y polymerase chain reaction amplification of t(14;18) or CDRm-rearrang
ements. Both devices yielded comparable purities (MACS 97% [87%-99%];
Isolex 97% [84%-99%]) and recoveries of CD34(+) cells (MACS 56% [30%-8
1%]; Isolex 45% [24%-63%]). The overall depletion of lymphoma cells wa
s 3.9 log (2.6-5.9), however, residual contaminating cells were seen i
n every single experiment, The purging efficacy was dependent on the t
ype of contaminating lymphoma cell (BALM-3: 4.4 log [3.7-4.8]; KARPAS4
22: 3.2 log [2.6-4.2];p = 0.018), whereas the type of selection system
used or the percentage of CD34(+) cells in the starting material had
no influence, We conclude that excellent purification of CB34(+) cells
leading to a vigorous depletion of lymphoma cells can be achieved wit
h both CD34(+) selection systems investigated, However, the efficacy o
f purging may greatly differ between individual lymphomas, and complet
e eradication of contaminating cells from PBPC grafts may rarely be ac
hieved with CD34(+) selection alone.