CD56bright natural killer regulatory cells in filgrastim primed donor blood or marrow products regulate chronic graft-versus-host disease: the Canadian Blood and Marrow Transplant Group randomized 0601 study results.

Randomized trials have conclusively shown higher rates of chronic graft-versus-host disease with filgrastim-stimulated apheresis peripheral blood as a donor source than unstimulated bone marrow. The Canadian Blood and Marrow Transplant Group conducted a phase 3 study of adults who received either filgrastim-stimulated apheresis peripheral blood or filgrastim-stimulated bone marrow from human leukocyte antigen-identical sibling donors. Because all donors received the identical filgrastim dosing schedule, this study allowed for a controlled evaluation of the impact of stem cell source on development of chronic graft-versus-host disease. One hundred and twenty-one evaluable filgrastim-stimulated apheresis peripheral blood and filgrastim-stimulated bone marrow patient donor products were immunologically characterized by flow cytometry and tested for their association with acute and chronic graft-versus-host disease within 2 years of transplantation. The immune populations evaluated included, regulatory T cells, central memory and effector T cells, interferon γ positive producing T cells, invariate natural killer T cells, regulatory natural killer cells, dendritic cell populations, macrophages, and activated B cells and memory B cells. When both filgrastim-stimulated apheresis peripheral blood and filgrastim-stimulated bone marrow were grouped together, a higher chronic graft-versus-host disease frequency was associated with lower proportions of CD56bright natural killer regulatory cells and interferon γ-producing T helper cells in the donor product. Lower CD56bright natural killer regulatory cells displayed differential impacts on the development of extensive chronic graft-versus-host disease between filgrastim-stimulated apheresis peripheral blood and filgrastim-stimulated bone marrow. In summary, while controlling for the potential impact of filgrastim on marrow, our studies demonstrated that CD56bright natural killer regulatory cells had a much stronger impact on filgrastim-stimulated apheresis peripheral blood than on filgrastim-stimulated bone marrow. This supports the conclusion that a lower proportion of CD56bright natural killer regulatory cells results in the high rate of chronic graft-versus-host disease seen in filgrastim-stimulated apheresis peripheral blood. clinicaltrials.gov Identifier: 00438958.

Acute myelogenous leukemia with t(8;21)--identification of a specific immunophenotype.

Association between certain surface markers and acute myelogenous leukemia (AML) with t(8;21) has been described. The specificity and the predictive values of these markers have never been assessed. In this study, we aimed, to explore whether a specific pattern could predict for this translocation. Of 405 consecutive AML, 18 (4.4%) had the t(8;21). Patients with this cytogenetic abnormality showed higher frequency of CD34 (P = 0.003), HLA-DR (P = 0.03), Tdt (P = 0.02), CD19 (P < 0.0001), and CD56 (P < 0.0001) and lower CD33 (P = 0.0001). Taken singly, the sensitivity of these markers for AML with t(8;21) ranged between 39 and 100% with CD34+ having the highest and CD33- having the lowest and the positive predictive values (PPV) ranged between 5 and 21% with CD19+ having the highest and HLA-DR+ having the lowest. When combinations of different markers were analyzed by multivariate analysis, the pattern CD34+/HLA-DR+/MPO+ was found to have the highest sensitivity (100%) with a PPV of 14% and the pattern CD34+/CD19+/CD56+ had the highest PPV (100%) with a sensitivity of 67%. We conclude that AML with t(8;21) is better identified by a combination of markers than by a single antigen pattern, the absence of CD34+, HLA-DR+ or MPO+ would preclude and the expression of the pattern CD34+/CD19+/CD56+ is highly predictive and could serve as a screening criteria for the t(8;21).