title: CD40 ligand-stimulated B cell precursor leukemic cells elicit interferon-gamma production by autologous bone marrow T cells in childhood acute lymphoblastic leukemia.
abstract: Childhood B cell precursor acute lymphoblastic leukemia (BCP-ALL) cells, collected from bone marrow (BM) at diagnosis, were cultured, after thawing, on allogeneic human bone marrow stroma (HBMS) for 48 h in the presence of a soluble trimeric CD40 ligand (stCD40L) molecule. HBMS maintained leukemic cells viability in all tested cases (mean viability 85%). Under these culture conditions we noticed upregulation or de novo expression of costimulatory molecules CD40, CD80 (B7-1) and CD86 (B7-2) in 22/22, 15/23 and 21/23 cases, respectively. Upregulation, in terms of fluorescence intensity, was also observed in the expression of MHC I, MHC II, CD54 (ICAM 1) and CD58 (LFA 3) molecules. HBMS alone, although to a lesser extent, was able to induce modulation of these molecules, but not CD80, in a similar proportion of cases. Neither stCD40L nor HBMS induced modulation of CD10 and CD34 molecules. Moreover, in 4/4 tested cases, stCD40L-stimulated ALL cells were able to induce allogeneic T cells proliferation. To evaluate whether leukemia-reactive T cells were detectable in the BM of ALL patients at diagnosis, stCD40L-stimulated ALL cells were co-cultured with autologous T cells (ratio 1:1), isolated from BM at diagnosis, for 4 days and a 24 h ELISPOT assay was applied to detect the presence of interferon-gamma (IFN-gamma)-producing cells. In four of seven cases IFN-gamma-producing cells were detected with frequencies of 1/900, 1/1560, 1/2150 and 1/1575 autologous T cells. These data confirm that stCD40L exposure can activate the antigen-presenting cell (APC) capacity of BCP-ALL cells cultured on HBMS and that ELISPOT assay can be used to measure the frequency of leukemia-reactive autologous T cells in the BM of ALL patients even after short-term culture with stCD40L-stimulated ALL cells.
mesh_terms: D000293:Adolescent; D001854:Bone Marrow Cells / Q000378:metabolism*; D023201:CD40 Ligand / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D018189:Immunomagnetic Separation; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000096:biosynthesis*; D007621:Karyotyping; D008297:Male; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism* / Q000473:pathology; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism*
chemical_list: D023201:CD40 Ligand; D007371:Interferon-gamma