Graft rejection Successful treatment of incipient graft rejection with donor leukocyte infusions, further proof of a graft versus host lymphohaemopoietic effect JL Dı´ez-Martı´n 1 , A Go´mez-Pineda 2 , D Serrano 1 , R Carrio´ n 1 , P Balsalobre 1 and I Bun˜ o 1 1 Unidad de Trasplante de Me´dula Osea, Hosp. G.U. Gregorio Maran˜o ´n, Madrid, Spain; and 2 Servicio de Hematologı´a, Hosp. G.U. GregorioMaran˜o ´n, Madrid, Spain Summary: Graft rejection is a major cause of treatment failure after T-cell-depleted stem cell transplantation (TCD-SCT) and remains a therapeutic challenge. Donor leukocyte infu- sions (DLIs) have an efficient graft versus host effect, which has been successfully used to treat recipient relapses. We hypothesized that this effect could be exploited to counteract the host versus graft reactions responsible for graft rejection. We report two adult patients with haematological malignancies who underwent sex-mismatched TCD-SCT from HLA-identical sibling donors. Peripheral blood (PB) counts and bone marrow (BM) cellularity were studied on a serial basis. Sequential chimaerism and minimal residual disease analysis were performed by FISH on PB and BM samples as well as on leukocyte lineages (T and B lymphocytes and myeloid cells) purified from PB using immunomagnetic techno- logy. Both patients were diagnosed with incipient graft rejection 2–3 months after engraftment, based on persistently decreasing PB counts and BM cellularity together with the observation of decreasing mixed chimaerism (increasing percentage of recipient cells), mostly in whole PB and T lymphocytes. Both patients were successfully treated with a single DLI (1  10 7 CD3 þ cells/kg), thereafter achieving normal PB counts and BM cellularity as well as complete chimaerism. Interestingly, the only side effect observed was mild graft versus host disease that did not require treatment. In conclusion, provided that an early diagnosis is made, the graft versus host lymphohaemopoietic effect harboured by immunocompetent donor cells can be successfully used for the treatment of incipient graft rejection. Bone Marrow Transplantation (2004) 33, 1037–1041. doi:10.1038/sj.bmt.1704488 Published online 5 April 2004 Keywords: graft rejection; T-cell depletion; donor leuko- cyte infusion; chimaerism; FISH Allogeneic stem cell transplantation (SCT), using either peripheral blood (PB) or bone marrow (BM), is nowadays the therapy of choice for an increasing number of patients with haematological and nonhaematological diseases. 1 Graft versus host disease (GVHD), infections and relapse are major factors causing morbidity and mortality after SCT. T-cell depletion of the graft has proven useful in reducing the incidence and severity of GVHD. 2 However, since T-cell-depleted (TCD) grafts are less immunocompe- tent than unmanipulated grafts, they show a reduced graft versus leukemia (GVL) effect, and are therefore associated with an increased risk of relapse. 3 Moreover, T-cell depletion increases the incidence of graft failure and graft rejection. 4 Other factors that contribute to graft rejection include HLA disparity between donor and recipient, severe chronic GVHD (cGVHD) or associated viral infections. 5 Once graft rejection is detected, the different possible causes should be carefully reviewed and, if identified, appropriately treated. Effective treatments for overt graft rejection are scarce and mainly based on second SCT, 6 which has been successfully used in a few selected patients. The objective of the present investigation was to show the usefulness of early diagnosis of graft rejection on the basis of persistently decreasing PB and BM cellularity together with decreasing mixed chimaerism (MC; increasing percen- tage of recipient cells) as well as the efficacy and safety of prompt therapy with donor leukocyte infusions (DLIs). Patients and methods We report two patients with haematological malignancies who underwent TCD-SCT (Table 1). Haemopoietic stem cells were harvested, after G-CSF mobilization (subcuta- neous administration of 10 mg/kg/day  5 days), from the PB of HLA and ABO identical sibling donors. The grafts were partially TCD by positive immunomagnetic selection of CD34 þ cells (Isolex 300i, Baxter in patient 1; CliniMACS, Miltenyi Biotec in patient 2). Table 1 shows patient characteristics, number of CD34 þ and CD3 þ cells infused, engraftment and acute GVHD (aGVHD) development. GVHD prophylaxis included cyclosporine A from day 1 in both patients. Donor leukocytes for DLI were obtained by apheresis procedures without prior G-CSF mobilization and infused without further GVHD prophylaxis. Received 19 September 2003; accepted 24 December 2003; published online 5 April 2004 Correspondence: Dr JL Dı´ez-Martı´n, BMT Unit, Department of Oncology (4th floor), Gregorio Maran˜ o´ n, G.U. Hosp., Doctor Esquerdo 46, 28007 Madrid, Spain. E-mail: jdiez.hgugm@salud.madrid.org Bone Marrow Transplantation (2004) 33, 1037–1041 & 2004 Nature Publishing Group All rights reserved 0268-3369/04 $25.00 www.nature.com/bmt