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Boyer <strong>and</strong> Y eager 97<br />

Table 2. Hypothetical breakdown of the components of both auto- <strong>and</strong> UD BMT as they<br />

contribute to outcome in patients with high-risk ALL<br />

AutoBMT UD BMT<br />

Purging -10% 0%<br />

Chemoradiotherapy +30% +30%<br />

GVL 0% +60%<br />

GVHD 0% -50%<br />

Total 20% 40%<br />

Further studies involving this approach are currently ongoing <strong>and</strong> include addition<br />

of immunostimulatory cytokines. Post-BMT interleukin (IL)-2 has been used in<br />

several studies of autoBMT for ALL but with no apparent positive effects. 1<br />

effects of systemic cytokines like IL-2 that activate nonspecific effectors, i.e.,<br />

natural killer (NK) <strong>and</strong> lymphocyte-activated killer (LAK) cells, may have a<br />

limited role in treating drug- <strong>and</strong>/or radiation-resistant ALL based on in vitro<br />

resistance to LAK-mediated cytotoxicity (Figs. 1 <strong>and</strong> 2). In contrast, cytotoxic T<br />

lymphocytes (CTL) maintain effectiveness against radiation-resistant ALL cell<br />

lines (Fig. 3). Currently, our laboratory is actively pursuing the generation of<br />

<strong>autologous</strong> CTL from leukemia patients, with the ultimate goal of identifying<br />

antigenic peptides that could serve as targets <strong>and</strong> allow in vivo vaccination<br />

approaches as have been used for melanoma. 15<br />

Figure 1. Bcl-2 overexpression in 697 ALL inhibits radiation-induced DNA fragmentation<br />

as measured by flow cytometry. Both 697 <strong>and</strong> 697Bcl-2 were exposed to 30 Gy g-irradiation<br />

from a cesium source <strong>and</strong> then fixed overnight in 1% paraformaldehyde followed by 70%<br />

ethanol. Cells were labeled at 39-hydroxy termini of DNA breaks with fluorescein isoth<br />

cyanate (FITC)-dUTP according to manufacturer's instructions. 20,000 events were acqui<br />

<strong>and</strong> analyzed with Cell Quest software. Shown are 697 in left panel <strong>and</strong>697Bcl-2 in right pan<br />

with percentages of FITC-positive cells both for unirradiated <strong>and</strong> 30 Gy-irradiated groups.<br />

The

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