Recurrent episodes of inflammation underlie numerous pathologies, notably those of inflammatory bowel diseases. In this study, we describe a population of macrophages in a novel state of activation that mitigates colitis in mice. The cells responsible for this effect, called IFN-γ-stimulated monocyte-derived cells (IFNγ-MdC), derive from mouse spleen, blood, and bone marrow monocytes and are distinguished from known macrophage populations by mode of generation, cell surface phenotype, and function. IFNγ-MdC only arise when macrophages are cultivated in the presence of CD40L-expressing CD4+ T cells, M-CSF, and IFN-γ. IFNγ-MdC express markers including F4/80, CD11b/c, CD86, and CD274; they are negative for CD4, CD8, Gr1, CD19, CD80, and CD207. Functionally, IFNγ-MdC are defined by their capacity to enrich cocultured T cell populations for CD4+CD25+Foxp3+ regulatory cells; this enrichment, constituting up to 60% or more of residual lymphocytes, is attributed to an expansion, but also to a cell contact and caspase-dependent depletion of activated T cells. In mice, IFNγ-MdC delivered i.v. traffic to gut-associated peripheral lymphoid tissues, including the mesenteric lymph nodes, Peyer’s patches, and colonic mucosa, and promote the clinical and histological resolution of chronic colitis. We conclude that IFNγ-MdC represent macrophages in a novel state of activation, possessing multiple T cell-suppressive effects with therapeutic potential for the treatment of autoimmune inflammation.

Summary Five renal transplant recipients were preoperatively treated with transplant acceptance‐inducing cells (TAICs) in a Phase‐I safety study of TAICs as an adjunct immune‐conditioning therapy in living‐donor kidney transplantation. Initially, patients received anti‐thymocyte globulin induction therapy in combination with tacrolimus and steroid immunosuppression. Over the course of 12 weeks, steroids were withdrawn and tacrolimus therapy was minimized. Three of the five patients were able to tolerate low‐dose tacrolimus monotherapy and one patient was withdrawn from all immunosuppression for over 8 months. No acute or delayed adverse events were associated with the infusion of TAICs. Monitoring of the recipient anti‐donor reactivity of TAIC‐treated patients in mixed lymphocyte cultures demonstrated that, during periods of clinically stable graft function, recipient T‐cell proliferation and cytokine secretion in response to stimulation with donor alloantigen was relatively suppressed. Therefore, although the TAIC‐II trial did not provide conclusive evidence of a beneficial effect of preoperative TAIC treatment, the results were encouraging because they suggest that TAICs promote a state of alloantigen‐specific unresponsiveness, which might allow safe minimization of pharmacological immunosuppression.

Summary The transplant acceptance‐inducing cell (TAIC) is a type of immunoregulatory macrophage with the capacity to specifically dampen allogeneic rejection responses to a degree allowing safe minimization of conventional immunosuppressive therapy. In the first part of this report, the production and phenotype of the human TAIC is described. In the second part, an analysis is given of the TAIC‐I clinical trial, in which 12 recipients of renal transplants from deceased donors were treated with donor‐derived TAICs as an adjunct immune‐conditioning therapy. Conventional immunosuppression was gradually withdrawn from 10 of these 12 patients over a period of 8 weeks, starting in the fourth week after transplantation. All but two patients tolerated cessation of steroid therapy, while the remaining eight patients were first weaned from sirolimus and then, in six cases, were also weaned to low‐dose tacrolimus monotherapy. It is concluded that TAIC therapy is both safe and clinically practicable; however, the TAIC‐I trial was unable to provide evidence that postoperative TAIC administration has a beneficial effect.

Summary This report describes the case of patient FR, a 31‐year‐old recipient of a living‐related kidney transplant from a donor against whom he was presensitized. Seventeen days prior to transplantation, a central venous infusion of transplant acceptance‐inducing cells (TAICs) was administered to the patient. During the 27‐month follow up, the patient experienced no acute rejection episodes under an immunosuppressive regime comprising anti‐thymocyte globulin (ATG) induction, corticosteroids and tacrolimus. In a similar manner to the kidney transplant recipients treated preoperatively with TAICs in a previous study, patient FR achieved a state of donor‐specific hypo‐responsiveness. Most remarkably, the deliberate preoperative exposure of a sensitized patient to the sensitizing alloantigen did not heighten his response; on the contrary, after TAIC treatment and transplantation, HLA‐specific antibodies were no longer detectable. The case of patient FR provides further evidence of the safety of pre‐transplantation treatment with TAICs.

Patient KW, a 36-yr-old male renal transplant recipient, received transplant acceptance-inducing cells (TAICs) as an adjunct immunosuppressive therapy. In the weeks post-transplantation, the patient's conventional immunosuppressive treatment was gradually minimized, such that, from the 21st wk post-transplantation onwards, the patient was stably maintained on tacrolimus monotherapy. Treatment with TAICs was without complication, both at the time of administration and in the four-yr follow-up period. It is concluded that the production and administration of TAICs to recipients of kidney transplants from deceased donors is technically feasible.

ITC meeting in 2007 a protocol amendment was introduced in October 2006. As treatment response to 4xR was shown to predict overall survival, risk stratifi cation according to response to rituximab was introduced. In the amended protocol patients with a CR after 4xR will go on with 4 additional applications of rituximab while all others will go on with four cycles of R-CHOP-21 instead of CHOP-21 (risk stratifi ed sequential treatment, RSST). Results: In this analysis from March 2008 a total of 86 patients are reported. The median follow up are 24.6 months for ST (69 pts. included) and 6.4 months for RSST (17 pts. included). 64 ST and 17 RSST patients were diagnosed with monomorphic PTLD, 5/0 with polymorphic PTLD. 22/9 patients were kidney, 16/4 liver, 14/4 heart, 4/0 lung, 2/0 heart+lung, 3/0 kidney+pancreas transplant recipients (8/0 others). Median age was 54/60 years. 59%/65% had advanced stage of disease. 51%/67% of tumors were EBV positive. 78%/82% of patients had late PTLD (i.e. later than 1 year after transplantation). LDH was elevated in 69%/56% of patients. The overall response rate of ST was 88% (CR 65%, PR 23%). 73.7% and 62.0% of patients included were without disease progression at one and two years, respectively, and 79.1% and 74.9% of patients responding remained in disease remission at 1 and 2 years (Fig 1). Following ST, 33% of patients suffered from WHO °3/4 infections. There were ten early therapyassociated deaths (17%), 6 due to infections, 2 due to haemorrhage, 2 due to primary refractory disease. With RSST the overall response rate was 92% and 85% achieved a complete remission. 92.9% of patients included were without disease progression at one year and with a median follow up of 6.4 months not a single patient responding to treatment had disease progression so far ( Fig 1). 5/15 patients (33%) suffered from WHO °3/4 infections. With RSST there were two early therapy-associated deaths (16%), one due to infection, one due to primary refractory disease. Conclusions: This is the largest prospective study in PTLD. Sequential treatment with rituximab and CHOP-21 + G-CSF is well tolerated and highly effective. As compared to rituximab monotherapy more patients achieve a CR with sequential treatment and time to progression (TTP) is very much prolonged. Our fi rst prospective data evaluating risk stratifi ed sequential treatment suggest even superior CR rates and further increased TTP with a similar toxicity level. Figure 1 Background: The use of immunomodulatory cells in organ transplantation is a promising approach for tolerance induction. Here we describe a novel tolerogenic macrophage population capable of enriching T regulatory (Treg) cells and promoting tolerance. Methods: Balb/c bone marrow, spleen and blood cells were cultured with M-CSF for 5 days, and on the last day IFN-gamma (IFN-g) was pulsed into the cultures to produce what we refer to as IFN-g-induced monocyte derived cells (IFNg-MdCs). IFNg-MdCs were phenotypically characterized by FACS and immunomodulation was determined by cell co...

Objectives: ABO-incompatible transplantation is performed worldwide because of donor paucity and availability of living donors with mismatched ABO blood group antigen. Despite removal of anti-A or anti-B antibodies prior to transplantation and immunosuppression, graft rejection can occur by antibodies elicited against the incompatible blood group antigen. We have been developing a gene therapy method to induce tolerance to B cells that produce antibodies to carbohydrate antigen by using autologous lymphocytes engineered to express the cognate antigen (). The objective of this study is to elucidate the effi cacy of the method in inducing B cell tolerance to ABO blood group antigens. Method: Using Nucleofector (Amaxa), mouse spleen lymphocytes and baboon peripheral blood lymphocytes were co-transfected with human A or B (A/B) transferase and human H transferase genes, which encode the gene synthesizing blood group A/B antigen and O antigen, respectively. The transfected lymphocytes were in vitro cultured, and the expression of A/B antigen on the lymphocytes was analyzed by fl ow cytometry. In order to induce tolerance to A/B antigen in mice, the transfected lymphocytes were intravenously administered into syngeneic mice 4~5 h post transfection. The injection was repeated 4 times in 3-4 day intervals. Then, the mice were weekly immunized 4 times with human blood type A/B red cell membranes, and the production of antibodies against A/B antigen was analyzed by ELISA. Results: Mouse lymphocytes expressed A/B antigen following the transfection with both of H transferase and A/B transferase genes but not with A/B transferase gene alone. The proportion of cells expressing the antigen was approximately 2% of the viable cells cultured in vitro for 24 h (65% viability). Control mice intravenously administered with mock-transfected lymphocytes developed anti-A/B antibodies in high titers following the immunizations with human red cell membranes. In contrast, the mice received lymphocytes engineered to express A/B antigen were tolerant to the antigen. In baboon, approximately 15% of transfected lymphocytes expressed A/B antigen in vitro with 90% viability 24 h post transfection. Tolerance induction in baboon is currently under study by injecting the transfected lymphocytes back to the own circulation. Conclusions: We could induce tolerance to B cells with specifi city to ABO antigens in mice. Further studies in baboons and/or other suitable experimental animals may enable us to apply this method for clinical ABO-incompatible transplantation.