Impact of CD34 Cell Dose on Acute Graft Versus Host Disease After Allogeneic Bone Marrow Stem Cell Transplantation

Allogeneic bone marrow transplantation is being performed more frequently for various haematological, oncologic, immune deficiency and metabolic diseases. Despite improvements in techniques to ensure histocompatibility, GVHD remains one of the more frequent complications of this procedure, resulting in significant morbidity and mortality. Although histocompatibility remains the strongest risk factor for acute GVHD, within the subset of patients receiving non-T-cell-depleted marrow transplants from HLA-matched related donors several other variables have been associated with an increased incidence of acute GVHD. These include diagnosis, recipient–donor sex mismatch, recipient age, female donor–male recipient pair, alloimmunised and/or parous donor, increased dose of total body irradiation (TBI), lower intensity of GVHD prophylaxis and cytomegalovirus seropositivity of recipient or donor [1,2]. Herein we have investigated whether demographic characteristics (of the patients and donors) and bone marrow composition (in terms of nucleated cells, MNC, CD34þ , CD3þ , CD4þ , CD8þ and CD56þ cells dose) are important risk factors for the development and the severity of acute GVHD after allogeneic bone marrow transplantation. From April 1995 to April 1999, 42 consecutive patients aged less than 60 years old were submitted to a myeloablative preparative regimen and an unmanipulated bone marrow stem cell graft from an HLA-matched related donor at the Division of Haematology, Udine. General patient characteristics and clinical features at presentation are listed in Table I. The conditioning regimen used for all the patients consisted of Busulfan 1 mg/kg b.w. forth daily from day 27 to 24 and cyclophosphamide 60 mg/kg b.w. once daily from day 23 to 22. GVHD prophylaxis consisted of cyclosporine (CSA) and methotrexate (MTX). CSA was administered at 3 mg/kg b.w. /day i.v. continuous infusion from day 21: doses were adjusted to maintain whole blood steady state or trough levels at 250–350 ng/ml by radioimmunossay (RIA) for parent drug. After engraftment, CSA was converted to oral, continued through day 210, and tapered off thereafter. MTX was administered at 10 mg/m i.v. on days þ1, þ3, þ6 and þ11. Patients were observed prospectively for the development of acute GVHD. The diagnosis of GVHD was based on clinical evidence (in occasional cases by histologic confirmation) and GVHD was graded according to Glucksberg and to IBMTR criteria. Characteristics of the bone marrow stem cell grafts and of donors are shown in Table II. Bone marrow cell collections were assessed for CD34, CD3, CD4, CD8, CD16, CD56 and CD19 by flow cytometry on the day of collection, which was the same of infusion in all the patients. In case of ABO incompatibility, only MNC were infused. All analysis was performed with the last evaluation date setting as December 2000. The prognostic factors analysed in univariate and in multivariable analysis either for the development and for the severity of acute GVHD were: patient age, donor age, donor sex, donor parity, pair CMV seronegative, CD34þ , CD3þ , CD4þ , CD8þ , CD56þ , MNC and nucleated cell dose, haematological engraftment (days to PMN . 1000/mmc and PLT . 50,000/mmc). The median time for neutrophil count higher than 1000/mmc was 21 days (12–40), while the median time for reaching a self-sustained platelet count higher than 50,000/mmc was 27 days (13–70).