ABSTRACT
The most compelling clinical evidence that lymphocytes meditate an anti-leukemia
effect comes from studies that used allogeneic donor lymphocyte infusions (DLI) to treat
relapse of myeloid leukemia after allogeneic hemopoietic cell transplantation (HCT)
(1-5). Lymphocyte transfusions from the original bone marrow (BM) donor induces
both hematological and cytogenetic responses in approximately 70-80% of patients
with chronic myelogenous leukemia (CML) in the chronic phase (CP) (4). Complete
cytogenetic responses are usually obtained between 1 and 4 months after DLI (6), and
approximately 80% of responders will achieve reverse transcriptase-polymerase chain
reaction (RT-PCR) negativity for the bcr-abl translocation gene [the fusion product of the
t(9;22) translocation found in CML] within 6 months (6). Acute myeloid leukemia (AML)
is also susceptible to the GVL effect, with 15-40% of patients obtaining remissions with
DLI alone (7). While significant GVHD occurs in approximately 50% of CML patients
treated with DLI and 90% of those patients respond, 55% of patients without GVHD also
have disease responses (1,2). These observations suggest that GVL may be separable from
GVHD.
