[Immunophenotyping study of bone marrow fractions obtained by elutriation in allogeneic bone marrow transplantation]

Bone marrow transplantation (BMT) is an effective treatment for acute and chronic leukaemias. Lymphocyte depletion of donor bone marrow for preventing GVHD has been associated with a higher incidence of relapse after allogeneic BMT. This association suggests an antileukaemic effect of donor lymphocytes. In vitro studies show that cytotoxic T lymphocytes (CD3+ CD56+) and NK cells (CD3-CD56+) have an antileukaemic effect. To know which specific subpopulation of lymphocytes are depleted by counterflow centrifugation or elutriation, we analysed B, T, NK cells and hematopoietic precursors in the marrow fractions after this procedure.

Eight patients (6 CML, 1 ALL, 1 B-CLL) received an allogeneic BMT with lymphocyte depletion of the bone marrow graft using elutriation. After a Percoll gradient, donor marrow mononuclear cells (MNC) were separated with this method in five fractions (F1 to F5).

Lymphocyte depletion of donor marrow was in average of 1.7 log. This depletion was also selective, the last fraction containing higher number of cytotoxic T lymphocytes and NK cells than the other fractions. Recovery of CD34+ cells in the four fractions concerning to post-Percoll marrow was 84%, most of them being in the last fraction.

The use of elutriation for lymphocyte depletion is a good method for graft manipulation with the feasibility to adjust a lymphocyte/Kg. dose. Elutriation may be effective in reducing the incidence and severity of graft versus host disease and preserving the antileukaemic effect.