Tailored Rabbit Antithymocyte Globulin Induction Dosing for Kidney Transplantation.

BACKGROUND: Rabbit antithymocyte globulin (rATG) is the most widely used kidney transplant induction immunotherapy in the United States. It was recently Food and Drug Administration approved for this indication with typical dose recommendations of 1.5 mg/kg for up to 7 days given via a central line. METHODS: We theorized that reduced rATG dosing when compared with conventional dosing (6-10.5 mg/kg) is safe and effective, leading to development of a risk-stratified treatment protocol. Five-year data from a retrospective cohort of 224 adult kidney transplants (2008-2013) with follow-up through 2015 is presented. Cumulative rATG doses of 3 mg/kg were administered peripherally to nonsensitized living donor recipients, 4.5 mg/kg to nonsensitized deceased donor recipients. A subset of higher immunologic risk recipients (defined as history of prior transplant, panel reactive antibody greater than 20%, or flow cytometry crossmatch positivity) received 6 mg/kg. RESULTS: There were no differences in patient or graft survival between the 3 groups. One-year rejection rates in the first 2 groups were 8.3% and 8.8%, respectively, comparable to contemporaneous rates reported to the Scientific Registry of Transplant Recipients. Dose tailoring permitted substantial cost savings estimated at US $1 091 502. Mean length of stay fell by almost 3 days as the protocol was refined. There were no episodes of phlebitis. Infection rates were comparable with those reported to the Scientific Registry of Transplant Recipients. CONCLUSIONS: The novel findings of the current study include peripheral administration, reduced dosing, favorable safety, excellent allograft outcomes, and clear associative data regarding reduced costs and length of stay.

Donor immune reconstitution after liver-small bowel transplantation for multiple intestinal atresia with immunodeficiency.

The syndrome of multiple intestinal atresia with immunodeficiency is a rare, invariably fatal congenital disorder. At 16 months of age, a child with this syndrome underwent liver-small bowel transplantation from a 1-of-6 HLA-matched donor. He acquired full enteral tolerance and normal liver function and has never shown evidence of allograft rejection. After mild graft-versus-host disease developed, studies revealed that more than 99% of his CD3(+) lymphocytes and 50% of his CD19(+) lymphocytes were of donor origin, whereas granulocytes and monocytes remained of recipient origin. He synthesizes polyclonal immunoglobulin G (IgG), IgA, and IgM and has developed antibodies to cytomegalovirus (CMV) and parainfluenza 3. His T lymphocytes are predominately CD3(+)CD4(-)CD8(-) with T-cell receptor gammadelta heterodimers and CD3(+)CD4(-)CD8(+) with CD8alphaalpha homodimers, populations consistent with an intraepithelial lymphocyte phenotypic profile. We postulate that he has engrafted a donor intestine-derived immune system and is incapable of rejecting his engrafted organs.

Lymphodepleting effects and safety of pentostatin for nonmyeloablative allogeneic stem-cell transplantation.

Nonmyeloablative allogeneic stem-cell transplantation (alloNST) is the focus of investigations searching for less-toxic transplantation regimens. We report studies on the kinetics of lymphodepletion and safety of pentostatin (PT) conditioning in alloNST. Patients with hematologic malignancy received mobilized blood from human leukocyte antigen-matched related (n=4) or unrelated (n=8) donors. PT 4 mg/m2 was administered on days -21, -20, and -19 and 200 cGy of total-body irradiation was administered on day -1, followed by cyclosporine A and mycophenolate mofetil. Mononuclear cell adenosine deaminase after PT was inhibited 84%. The absolute CD3+ cells decreased significantly by day -7 (49%) and CD19+ cells declined 92% by day -1. CD4+ cells were depressed more than CD8+ cells. Neutrophils and monocytes were minimally affected by PT. Median posttransplant peripheral blood chimerism on day 70 showed 95% donor leukocytes and 82.5% donor CD3 lymphocytes. PT demonstrated lymphodepleting effects and promising safety, supporting alloNST as early as 7 days after initiation of PT.

The distribution of gene segments in T-cell receptor gamma gene rearrangements demonstrates the need for multiple primer sets.

Limited data exist regarding the distribution of gene segments used in T-cell receptor gamma gene rearrangements (TCR gamma GR) in T-cell lymphoproliferative disorders. The reported efficacy of TCR gamma GR protocols ranges from 60% to greater than 90%. Laboratories reporting a lower detection rate tend to use a limited set of primers. The goal of our study was to provide TCR gamma GR data to demonstrate the molecular biological basis for needing multiple primer sets targeting all gene segments. Sixty cases with a confirmed histological diagnosis of a T-cell lymphoproliferative disorder and TCR gamma GR were identified in our lymphoma registry from 1995 to 2001. DNA was obtained from fresh/frozen tissue, cell lysates, or paraffin-embedded tissue. Variable (V gamma) region gene segments were identified using denaturing gradient gel electrophoresis, which was used to select the cases in the study. Capillary electrophoresis using fluorescent-labeled joining (J gamma) region primers was performed to identify J gamma segments. Sixty cases contained a total of 98 TCR gamma GR, as some cases have more than one rearrangement. The most frequent gene segment combination involved the V gamma 1-8 and J gamma 1/2 segments. If a single primer set directed at these two segments were used for clinical diagnosis, that pair of primers would only diagnose 67% of cases as positive for TCR gamma GR. Our gene segment distribution data emphasize the importance of using a comprehensive set of V gamma and J gamma primers for an optimal detection rate of TCR gamma GR. Protocols with limited numbers of primers should be reconsidered.

Heart xenograft survival with chimeric pig donors and modest immune suppression.

OBJECTIVE: To assess the use of donor pigs with cellular chimerism for prevention of acute rejection with modest immune suppression. The clinical use of pig organ xenografts is currently precluded by severe acute rejection, which resists standard immune suppression. SUMMARY BACKGROUND DATA: For long-term survival of pig organ xenografts, immune suppression significantly greater than used with allografts would currently be necessary, leaving the recipient immune deficient and at increased risk for infections. Induction of immune tolerance and tissue accommodation could enhance xenograft survival but would lead to complications and frequent graft failure. Induction of cellular chimerism within the donor pigs, however, could accomplish these goals before transplantation, significantly reducing the risk. METHODS: Marrow cells from sheep were infused into fetal pigs. Heart xenografts from chimeric or nonchimeric pigs were transplanted heterotopically into recipient sheep, simultaneous with infusion of splenocytes. Posttransplant suppression consisted of cyclosporine and tapered corticosteroids, comparable with allotransplants. RESULTS: All of the control grafts (n = 12) were rejected by acute vascular rejection in 4 to 8 days. In contrast, only one episode of vascular rejection was observed in the experimental group (n = 13). Four experimental recipients had an episode of moderate diffuse cellular rejection (grade 3) and one had moderate focal cellular rejection (grade 2). Each episode responded to pulse steroids. Seven grafts showed no significant rejection. There was little evidence of immune deficiency, infection, or toxicity. CONCLUSIONS: Acute vascular rejection was prevented in a large animal model without the need for severe immune suppression.

Fatal immune restoration disease in human immunodeficiency virus type 1-infected patients with progressive multifocal leukoencephalopathy: impact of antiretroviral therapy-associated immune reconstitution.

Immune reconstitution resulting from use of highly active antiretroviral therapy in patients infected with human immunodeficiency virus type 1 (HIV-1) has been associated with a significant decrease in infectious morbidity and with improved survival. Occasionally, patients with quiescent disease due to human cytomegalovirus or nontuberculous mycobacteria may experience paradoxical worsening due to "dysregulated" restitution of the immune system (that is, immune restoration disease [IRD]). Acquired immunodeficiency syndrome-related progressive multifocal leukoencephalopathy (PML) is uncommon and often improves with immune recovery. We describe 2 HIV-1-infected patients with PML that presented with paradoxical worsening after the patients had commenced active antiretroviral therapy. After they had a transient response to high-dose corticosteroid therapy, both patients died of progressive neurological deterioration. IRD in these patients with PML was unexpected and occurred soon after they had started receiving active antiretroviral therapy, during the period of improved antigen-specific T-helper cell function. Predictors of patients' proclivity for these adverse events are uncertain. Evaluation of targeted immunomodulatory therapy directed towards disease-specific IRD is critical and may play an important role in improved survival for patients who are at risk.

Effectiveness of capillary electrophoresis using fluorescent-labeled primers in detecting T-cell receptor gamma gene rearrangements.

We describe the use of fluorescent-labeled primers to analyze T-cell receptor gamma gene rearrangements (TCR gamma GR) using capillary electrophoresis in the ABI Prism 310 Genetic Analyzer. We also compare the performance with denaturing gradient gel electrophoresis (DGGE). In a single multiplex polymerase chain reaction (PCR) we amplified TCR gamma GR with primers for all known groups of variable region genes, and joining region genes described in lymphoid neoplasms. Ten reactive samples, followed by five cell lines and 25 tumor samples with 41 individual TCR gamma GR (due to many biallelic rearrangements) previously identified by DGGE, were analyzed to validate the technique. The capillary electrophoresis protocol has 92% concordance for both TCR clonal status (23 of 25) and 95% concordance in the number of individual TCR gamma GR (38 of 41) identified by DGGE. The reproducible sensitivity for detecting TCR gamma GR diluted in reactive lymphoid DNA is 2% in clinical applications. Discrimination of predominant rearrangements requires a minimum ratio of two times the height of the normal distribution of polyclonal peaks. Capillary electrophoresis can provide results within 60 minutes for each specimen after PCR is complete. Capillary electrophoresis provides a faster result than sequence-based separation methods and gives an archival electronic record. Fluorescent labeling allows the identification of both the variable and joining gene segments used in a TCR gamma GR. The effectiveness of capillary electrophoresis is similar to DGGE.