GENERATION OF LEUKEMIA-REACTIVE CYTOTOXIC T-LYMPHOCYTES FROM HLA-IDENTICAL DONORS OF PATIENTS WITH CHRONIC MYELOID-LEUKEMIA USING MODIFICATIONS OF A LIMITING DILUTION ASSAY

Donor leukocyte transfusions (DLT) have an anti-leukemic effect in mos t patients with a relapse of chronic myeloid leukemia (CML) after allo geneic stem cell transplantation. However, DLT are often complicated b y graft-versus-host disease, Selection of donor lymphocytes with a rel ative specificity for leukemic cells is desirable, The generation of l eukemia-reactive cytotoxic T lymphocyte (CTL) responses between HLA-id entical donors and patients in bulk cultures showed major variations, and false negative results were observed, In a modification of a limit ing dilution analysis (LDA) two-fold serial dilutions of HLA-identical donor mononuclear cells (MNC) were cultured in the presence of CML ce lls, The anti-leukemic CTL precursor frequencies in these donors varie d between <1 and 9 per 10(6) MNC, KLA-restricted CD4(+) or CD8(+) lymp hocytes as well as MHC non-restricted gamma delta T cells were respons ible for the anti-leukemic responses, A positive correlation between c ytotoxicity in the various wells after 3, 4 and 5 weeks of culture cou ld be found, The LDA may be superior to bulk cultures in selecting sta ble immune responses and in separating multiple different antileukemic T cell responses in each donor-patient combination.