Thymic selection of CD4+CD25+ regulatory T cells induced by an agonist self-peptide

Despite accumulating evidence that regulatory T cells play a crucial role in preventing autoimmunity, the processes underlying their generation during immune repertoire formation are unknown. We show here that interactions with a single self-peptide can induce thymocytes that bear an autoreactive T cell receptor (TCR) to undergo selection to become CD4+CD25+ regulatory T cells. Selection of CD4+CD25+ thymocytes appears to require a TCR with high affinity for a self peptide because thymocytes that bear TCRs with low affinity do not undergo selection into this pathway. Our findings indicate that specificity for self-peptides directs the selection of CD4+CD25+ regulatory thymocytes by a process that is distinct from positive selection and deletion.

Regulation of pancreatic beta-cell growth and survival by the serine/threonine protein kinase Akt1/PKBalpha

The physiological performance of an organ depends on an interplay between changes in cellular function and organ size, determined by cell growth, proliferation and death. Nowhere is this more evident than in the endocrine pancreas, where disturbances in function or mass result in severe disease. Recently, the insulin signal-transduction pathway has been implicated in both the regulation of hormone secretion from beta cells in mammals as well as the determination of cell and organ size in Drosophila melanogaster. A prominent mediator of the actions of insulin and insulin-like growth factor 1 (IGF-1) is the 3'-phosphoinositide-dependent protein kinase Akt, also known as protein kinase B (PKB). Here we report that overexpression of active Akt1 in the mouse beta cell substantially affects compartment size and function. There was a significant increase in both beta-cell size and total islet mass, accompanied by improved glucose tolerance and complete resistance to experimental diabetes.

Induction of donor-specific unresponsiveness by intrathymic islet transplantation

The application of isolated pancreatic islet transplantation for treatment of diabetes mellitus has been hampered by the vulnerability of islet allografts to immunologic rejection. Rat islet allografts that were transplanted into the thymus of recipients treated with a single injection of anti-lymphocyte serum survived indefinitely. A state of donor-specific unresponsiveness was achieved that permitted survival of a second donor strain islet allograft transplanted to an extrathymic site. Maturation of T cell precursors in a thymic microenvironment that is harboring foreign alloantigen may induce the selective unresponsiveness. This model provides an approach for pancreatic islet transplantation and a potential strategy for specific modification of the peripheral immune repertoire.

Randomised trial of hysterectomy, endometrial laser ablation, and transcervical endometrial resection for dysfunctional uterine bleeding

OBJECTIVE

To evaluate the effectiveness and safety of endometrial laser ablation and transcervical resection of the endometrium compared with hysterectomy in the surgical treatment of women with dysfunctional uterine bleeding.

DESIGN

Prospective randomised controlled trial.

SETTING

Gynaecology department of a large teaching hospital.

SUBJECTS

204 women who would otherwise have been undergoing hysterectomy for menorrhagia were recruited between August 1990 and March 1992 and randomly allocated to hysterectomy (n = 99) or conservative (hysteroscopic) surgery (transcervical resection (n = 52) and laser ablation (n = 53)).

MAIN OUTCOME MEASURES

Operative complications, postoperative recovery, relief of menstrual and other symptoms, patient satisfaction with treatment after six and 12 months.

RESULTS

Women treated by hysteroscopic surgery had less early morbidity and a significantly shorter recovery period than those treated by hysterectomy (median time to full recovery 2-4 weeks v 2-3 months, P < 0.001). Twelve months later 17 women in the hysteroscopy group had had a hysterectomy, 11 for continuing symptoms; 11 women had had a repeat hysteroscopic procedure; 45 were amenorrhoeic or had only a brown discharge; and 35 had light periods. Dysmenorrhoea and premenstrual symptoms improved in most women in both groups. After 12 months 89% (79/89) in the hysterectomy group and 78% (75/96) in the hysteroscopy group were very satisfied with the effect of surgery (P < 0.05); 95% (85/89) and 90% (86/96) thought that there had been an acceptable improvement in symptoms, and 72% (64/89) and 71% (68/96) would recommend the same operation to others.

CONCLUSIONS

Hysteroscopic endometrial ablation was superior to hysterectomy in terms of operative complications and postoperative recovery. Satisfaction after hysterectomy was significantly higher, but between 70% and 90% of the women were satisfied with the outcome of hysteroscopic surgery. Hysteroscopic surgery can be recommended as an alternative to hysterectomy for dysfunctional uterine bleeding.

Antigen presenting function of class II MHC expressing pancreatic beta cells

Class II major histocompatibility complex (MHC) gene expression in the mouse is generally limited to thymic epithelium and bone marrow-derived cells such as B lymphocytes and cells of the macrophage/dendritic cell lineage (M phi/DC). Class II-bearing B lymphocytes and M phi/DC possess antigen presenting cell (APC) function; that is, they can stimulate T lymphocytes reactive to either antigen plus MHC or foreign MHC alone. To assess whether non-bone-marrow-derived cells can acquire APC function and elicit graft rejection through expression of class II, we studied transgenic pancreatic islet beta cells that express a foreign class II (I-E) molecule. In vivo, grafts of I-E+ transgenic islets into I-E- naive hosts are not rejected unless the host is primed by an injection of I-E+ spleen cells. In vitro, the I-E+ beta cells are unable to stimulate T lymphocytes reactive to I-E plus a peptide antigen. Paradoxically, they induce antigen specific unresponsiveness in the T cells. We propose that expression of class II on non-lymphoid cells may serve as an extrathymic mechanism for maintaining self tolerance.

B-cells are required for the initiation of insulitis and sialitis in nonobese diabetic mice

Nonobese diabetic (NOD) mice spontaneously develop an acute onset of hyperglycemia reminiscent of human type I diabetes. The disease is the end result of a mononuclear cell infiltration of pancreatic islets (insulitis), culminating in the selective destruction of islet beta-cells by autoreactive T-cells. NOD mice also exhibit defects in B-cell tolerance as manifested by the presence of autoantibodies against islet cell autoantigens. Based on the potential ability of B-cells to act as antigen presenting cells, we hypothesized that autoreactive B-cells of NOD mice may be necessary for the activation of islet reactive CD4+ T-cells. In the present study, we utilized an anti-mu antibody to induce in vivo depletion of B-cells and found that B-cell depletion completely abrogates the development of insulitis and sialitis in NOD mice. In contrast, control IgG-treated NOD mice developed insulitis and sialitis by 5 weeks of age. Additionally, the discontinuation of anti-mu chain antibody treatment led to the full restoration of the B-cell pool and the reappearance of insulitis and sialitis. Thus, we conclude that B-cells are a requisite cell population for the genesis of the inflammatory lesions of the islets of Langerhans. This finding suggests that autoreactive B-cells may act as the antigen presenting cells necessary for the initial activation of beta-cell-reactive CD4+ T-cells implicated in the pathogenesis of autoimmune diabetes.

High levels of glucose-6-phosphatase gene and protein expression reflect an adaptive response in proliferating liver and diabetes

The regenerating liver after partial hepatectomy is one of the few physiologic models of cellular proliferation in the adult animal. During hepatic regeneration, the animal is able to maintain metabolic homeostasis despite the acute loss of two thirds of hepatic tissue. In examining the molecular mechanisms regulating hepatic regeneration, we isolated novel immediate-early genes that are rapidly induced as the remnant liver undergoes the transition from its normal quiescent state into the G1 phase of the cell cycle. One of the most rapidly and highly induced genes which we initially termed RL-1, encodes rat glucose-6-phosphatase (rG6Pase). G6Pase mRNA peaks at 30 min and 36-48 h after hepatectomy correlating with the first and second rounds of cell division. This finding is compatible with studies that showed that G6Pase enzyme activity increases during liver regeneration. However, the increase in G6Pase mRNA is much more dramatic, indicating that it is a more sensitive indicator of this regulation. G6Pase gene expression peaks in the perinatal time period in the liver and remains elevated during the first month of life. The expression of the G6Pase gene is also dramatically elevated in BB diabetic rats, again higher than the enzyme elevation, and its relative induction after partial hepatectomy is blunted in these animals. Insulin treatment of partially hepatectomized diabetic animals downregulates the expression of G6Pase mRNA. Using specific antibodies against G6Pase, we detect a 36-kD G6Pase protein, and its level is elevated in regenerating and diabetic livers. The pattern of G6Pase mRNA expression appears to reflect similar changes in insulin and glucagon levels which accompany diabetes and hepatic proliferation. The elevation of G6Pase expression in these conditions is indicative of its importance as a regulator of glucose homeostasis in normal and abnormal physiologic states.

Prevention of autoimmune diabetes in the BB rat by intrathymic islet transplantation at birth

Spontaneous diabetes in the BioBreeding (BB) rat, like human type I diabetes, results from the destruction of pancreatic islets by autoreactive T lymphocytes recognizing beta cell-specific antigens. T cell tolerance is in part mediated by interactions of maturing thymocytes with antigens expressed in the thymic microenvironment; islets were therefore implanted into the thymus of neonatal diabetes-prone BB rats to determine whether exposure of T cell precursors to beta cell antigens could influence the development of diabetes. This treatment completely prevented diabetes and insulitis in the native pancreas. The effect may be the result of specific modulation of diabetogenic T cells maturing in an islet-bearing thymus.

Adrenal suppression and steroid supplementation in renal transplant recipients

The use of increased dosages of glucocorticoids during periods of physiologic stress in allograft recipients represents a clinical dilemma in that the short-term exogenous therapy required may significantly impair wound healing and immunocompetence. To investigate whether "stress steroids" are actually necessary, a prospective study was conducted in 40 renal allograft recipients admitted with significant physiologic stress. Stress categories included sepsis, metabolic abnormalities, and surgery. These patients received only their baseline prednisone immunosuppression (5-10 mg/day) and no supraphysiologic or stress doses of glucocorticoids. The clinical course of the patients revealed no evidence of adrenal insufficiency. There was no mortality, increase in hospital stay, or eosinophilia. Five episodes of hyponatremia and seven instances of hypotension were attributed to primary disease processes and responded promptly to specific treatment without steroid supplementation. Biochemical evaluation during stress revealed suppression of ACTH levels in 74.5% of episodes, elevation of urinary free cortisol levels in 79.1% of episodes, and elevation of isolated serum cortisol levels in 55.9% of episodes. This suggested that these patients had physiologically adequate adrenal function. The cosyntropin stimulation test overestimated the incidence and degree of clinically significant adrenal dysfunction (63% of patients) and was not a useful indication of a requirement for additional glucocorticoids. We conclude that functional adrenal suppression is uncommon in renal allograft recipients receiving baseline prednisone immunosuppression (5-10 mg/day) and that the demands of physiologic stress are met by a combination of endogenous adrenal function plus exogenous, baseline, immunosuppressive doses of glucocorticoids. Supra-physiologic or high doses of so-called "stress steroids" are not required. The cosyntropin stimulation test has significant clinical limitations and did not serve to alter clinical care.

Wait list death and survival benefit of kidney transplantation among nonrenal transplant recipients

The disparity between the number of patients waiting for kidney transplantation and the limited supply of kidney allografts has renewed interest in the benefit from kidney transplantation experienced by different groups. This study evaluated kidney transplant survival benefit in prior nonrenal transplant recipients (kidney after liver, KALi; lung, KALu; heart, KAH) compared to primary isolated (KA1) or repeat isolated kidney (KA2) transplant. Multivariable Cox regression models were fit using UNOS data for patients wait listed and transplanted from 1995 to 2008. Compared to KA1, the risk of death on the wait list was lower for KA2 (p < 0.001;HR = 0.84;CI = 0.81-0.88), but substantially higher for KALu (p < 0.001; HR = 3.80;CI = 3.08-4.69), KAH (p < 0.001; HR = 1.92; CI = 1.66-2.22), and KALi (p < 0.001; HR = 2.69; CI = 2.46-2.95). Following kidney transplant, patient survival was greatest for KA1, similar among KA2, KALi, KAH, and inferior for KALu. Compared to the entire wait list, renal transplantation was associated with a survival benefit among all groups except KALu (p = 0.017; HR = 1.61; CI = 1.09-2.38), where posttransplant survival was inferior to the wait list population. Recipients of KA1 kidney transplantation have the greatest posttransplant survival and compared to the overall kidney wait list, the greatest survival benefit.

Spontaneous diabetes in rats: destruction of islets is prevented by immunological tolerance

Spontaneous diabetes occurring in "BB" rats (derived from a colony of outbred Wistar rats) is the result of destruction of pancreatic islets by infiltrating mononuclear cells (insulitis) and may be a disease very similar to human juvenile onset diabetes. Both diseases probably have an autoimmune etiology. Evidence is presented that islets transplanted to diabetic BB rats are destroyed by the original disease process. Inoculation of bone marrow from normal (nondiabetes-susceptible) rat donors into neonatal BB recipients usually prevented the development of hyperglycemia.

Percutaneous thrombolysis and stent placement for the treatment of portal vein thrombosis after liver transplantation: long-term follow-up

BACKGROUND

The durable use of percutaneous minimally invasive techniques for the treatment of portal venous thrombosis after liver transplant has not been widely described. This report illustrates two cases in which percutaneous thrombolysis, angioplasty, and endovascular stent placement were successfully used to treat portal vein thrombosis in patients with recent liver transplants.

METHODS

Liver dysfunction was initially manifested by the elevation of liver enzymes or the development of marked ascites and confirmed in both cases by sonography and angiography. The occluded portal vein was accessed by either a transjugular transhepatic puncture or direct transhepatic catheterization. Intraportal thrombolytic infusion, angioplasty, and stent placement were accomplished without complication.

RESULTS

At the most recent follow-up, portal vein patency had been maintained for 2.5 and 4.5 years.

CONCLUSIONS

These results demonstrate the technical feasibility and long-term patency of angioplasty and endovascular stent placement for the treatment of portal vein thrombosis in liver transplant recipients.

Immunologic effects of arginine supplementation in tumor-bearing and non-tumor-bearing hosts

Supplemental dietary arginine has anti-tumor properties but the degree and mechanisms are unclear. In non-tumor-bearing CBA/J mice (n = 60), 1% arginine supplementation significantly enhanced thymic weight, spleen cell mitogenesis, and interferon-activated natural killer cell activity; no further enhancement was observed with 2% or 4% supplementation. Supplemental 1% arginine, when compared with 1.7% glycine, enhanced interferon-induced natural killer cell activity, lymphokine-activated killer cell generation, and macrophage cytotoxicity. In A/J mice (n = 420), bearing either a moderately immunogenic (C1300) or weakly immunogenic (TBJ) murine neuroblastoma, 1% arginine significantly (p less than 0.05) retarded tumor growth and prolonged median survival time compared with glycine or no supplementation. Dietary arginine enhanced T-cell function and significantly increased responsiveness to autologous C1300 tumor in a mixed lymphocyte tumor cell culture (MLTC). The immunomodulatory effects of arginine provide nutritional and immunologic support of the tumor-bearing host and may be helpful when given concommitant with immunotherapy.

Mycophenolic acid area under the curve values in African American and Caucasian renal transplant patients are comparable

The possibility of an effect of ethnicity on the pharmacokinetics of mycophenolic acid, the immunosuppressive metabolite of the prodrug mycophenolate mofetil, was studied over 90 days following renal transplantation in African American (n = 13) and Caucasian patients (n = 20). Since renal dysfunction and time after transplant surgery are two factors known to alter mycophenolic acid pharmacokinetics, two-way analysis of variance of the data at each time point with ethnicity and renal function status as covariates was used to evaluate the possibility of an ethnicity effect on the pharmacokinetic parameters. No statistically significant difference based on ethnicity was detected for the primary pharmacokinetic parameters, abbreviated mycophenolic acid area under the concentration-time curve (MPA AUC), or the predose trough concentration on study days 4, 7, 14, 28, or 90. A statistically significant decrease in MPA AUC and increase in oral apparent clearance were observed in renally impaired patients regardless of ethnicity on days 4, and 4 and 7, respectively. The suggested mechanism for these differences is uremia-induced increased MPA free fraction, leading to a temporary increased clearance for this restrictively cleared drug.

Percutaneous transluminal angioplasty treatment of renal transplant artery stenosis

Since June 1979, percutaneous transluminal angioplasty (PTA) has been the procedure of choice for renal transplant artery stenosis (RTAS) at the Hospital of the University of Pennsylvania. Of 241 renal allograft recipients, 17 (7%) when studied by arteriogram because of suspected RTAS proved to have significant stenosis (the mean reduction in luminal width for the group being 68%) and underwent PTA. RTAS was equally prevalent in cadaver and related kidney allografts and was no less common in HLA-identical related donor grafts, arguing against the importance of immune factors in etiology. RTAS was equally prevalent whether the anastomotic technique was end to end or end to side. However, when RTAS occurred after end to side anastomoses, it was usually postanastomotic. Fifteen of 17 of the attempts at dilation by PTA were successful by angiographic analysis. Thirteen of the 15 successfully dilated patients had long-term allograft survival and in all of these instances blood pressure (BP) was decreased after PTA. After a mean of 67 weeks, BP decreased from a systolic of 184 +/- 24 mm Hg pre-PTA to 135 +/- 15 mm Hg (P less than 0.001) and from a diastolic of 115 +/- 10 mm Hg pre-PTA to 87 +/- 11 mm Hg (P less than 0.001). The majority of patients continue to require antihypertensive drugs but in a less vigorous regimen than pre-PTA. Serum creatinine level fell following PTA from 1.9 +/- 0.6 to 1.7 +/- 0.5 mg/100 ml (P less than 0.01). Repeat angiographic study was done in nine patients, an average of 61 weeks after PTA, and no recurrent RTAS was identified. Three minor complications of PTA occurred but none led to long-term sequelae. Thus, we believe PTA of RTAS is relatively safe, carrying less mortality and morbidity than operative treatment, and is capable of improving BP control and renal allograft function.

NK resistance of tumor cells from multiple myeloma and chronic lymphocytic leukemia patients: implication of HLA-G

Exploiting the antitumor effect of natural killer (NK) cells has regained interest in light of data from preclinical and clinical work on the potential of alloreactive NK cells. Multiple myeloma (MM) and chronic lymphocytic leukemia (CLL) represent the two most prevalent adult hematological malignancies in the western hemisphere. To evaluate the role of NK cells in the immune surveillance and their therapeutic potential for CLL and MM, tumor cell susceptibility to NK-mediated killing was investigated. Results show relative resistance of tumor cells from CLL as well as MM (73 and 70% of the patients, respectively) to NK-mediated killing. To gain insight into molecular mechanisms of this resistance, the expression of the tolerogenic HLA-G molecule in CLL and MM and its relevance to susceptibility to NK-mediated killing were investigated. HLA-G transcript was found in tumor cells from 89% (n=19) of CLL and 100% (n=9) of MM patients examined. HLA-G1 surface expression was observed in CLL and was very low or undetectable in MM. Notably, blocking of HLA-G1 with specific antibody on CLL samples increased their susceptibility to NK-mediated killing, demonstrating that HLA-G participates in protecting CLL cells from NK-mediated killing and may thus contribute to their immune escape in vivo.

Cytocompatibility of two coating materials, amorphous alumina and silicon carbide, using human differentiated cell cultures

The cytocompatibility of two coating materials, amorphous alumina and silicon carbide deposited by radio-frequency sputtering, was studied using alveolar bone osteoblasts and gingival fibroblasts from human healthy tissues. Cytocompatibility was assessed at the level of both the basic (attachment, proliferation and cell protein content) and the specific features (intracellular alkaline phosphatase activity and the cytoskeleton) of the cells in direct contact with the coating. Titanium was used as the reference material. The results showed that both silicon carbide and amorphous alumina are cytocompatible for human fibroblasts and osteoblasts, whereas titanium appears the least cytocompatible of all the three substrates. Moreover, the amorphous alumina coating seems slightly bioactive. It seems that these coatings, particularly amorphous alumina, could be used to protect alloys against corrosion, and consequently combine the good mechanical properties of the alloys with the good biocompatibility of the coatings. These coatings seem to perform more suitably than titanium if the strength of the bond between the coating and the underlying alloys is strong enough to give a stable composite material.

Attraction of like-charged macroions in the strong-coupling limit

Like-charged macroions attract each other as a result of strong electrostatic correlations in the presence of multivalent counterions or at low temperatures. We investigate the effective electrostatic interaction between i) two like-charged rods and ii) two like-charged spheres using the recently introduced strong-coupling theory, which becomes asymptotically exact in the limit of large coupling parameter (i.e. for large counterion valency, low temperature, or high surface charge density on macroions). In contrast to previous applications of the strong-coupling theory, we deal with curved surfaces and an additional parameter, referred to as Manning parameter, is introduced, which measures the ratio between the radius of curvature of macroions to the Gouy-Chapman length. This parameter, together with the size of the confining box enclosing the two macroions and their neutralizing counterions, controls the counterion-condensation process that directly affects the effective interactions. For sufficiently large Manning parameters (weakly-curved surfaces), we find a strong long-ranged attraction between two macroions that form a closely-packed bound state with small surface-to-surface separation of the order of the counterion diameter in agreement with recent simulations results. For small Manning parameters (highly-curved surfaces), on the other hand, the equilibrium separation increases and the macroions unbind from each other as the confinement volume increases to infinity. This occurs via a continuous universal unbinding transition for two charged rods at a threshold Manning parameter of Epsilon c = 2/3, while the transition is strongly discontinuous for spheres because of a pronounced potential barrier at intermediate distances. Unlike the cylindrical case, the attractive forces between spheres disappear slowly for increasing confinement volume due to the complete de-condensation of counterions. Scaling arguments suggest that for moderate values of coupling parameter, strong-coupling predictions remain valid for sufficiently small surface-to-surface separations.

Glutamine enhancement of structure and function in transplanted small intestine in the rat

Total parenteral nutrition is required by all patients in need of small bowel transplantation. Untoward side effects of total parenteral nutrition include atrophy and hypofunction of the small intestine. Glutamine, the preferred fuel for the enterocyte, is presumably present in insufficient amounts in diets given to patients with intestinal dysfunction. In a rat model of total parenteral nutrition and small bowel transplantation, this study investigated the following: (1) whether glutamine improves graft structure and function, (2) the optimal route of glutamine delivery (intravenous vs direct infusion into the graft), and (3) the effect of glutamine on ultrastructure of the graft enterocyte. Lewis rats underwent small bowel transplantation as a Thiry-Vella graft and received total parenteral nutrition for 14 days while assigned to one of four infusion groups: 2% intravenous glutamine; 2% intravenous isonitrogenous mixture, nonessential amino acids (control); 2% glutamine into the graft; or 2% nonessential amino acids into the graft (control). Graft mucosal villous height, villous surface area, crypt depth, weight, protein, deoxyribonucleic acid content, glucose absorption, and enterocyte ultrastructure were then evaluated. Infusion of glutamine directly into the graft significantly increased mucosal villous height (p = .045), surface area (p = .029), and glucose absorption (p = .004) when compared with controls. Intravenous glutamine infusion significantly increased mucosal villous height (p = .002), surface area (p = .001), weight (p = .005), and glucose absorption (p = .04) when compared with controls. Most enterotrophic and functional benefits of glutamine were not significantly different between intravenous infusions and direct administration into the graft.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired activation of islet-reactive CD4 T cells in pancreatic lymph nodes of B cell-deficient nonobese diabetic mice

Despite the impressive protection of B cell-deficient (muMT(-/-)) nonobese diabetic (NOD) mice from spontaneous diabetes, existence of mild pancreatic islet inflammation in these mice indicates that initial autoimmune targeting of beta cells has occurred. Furthermore, muMT(-/-) NOD mice are shown to harbor a latent repertoire of diabetogenic T cells, as evidenced by their susceptibility to cyclophosphamide-induced diabetes. The quiescence of this pool of islet-reactive T cells may be a consequence of impaired activation of T lymphocytes in B cell-deficient NOD mice. In this regard, in vitro anti-CD3-mediated stimulation demonstrates impaired activation of lymph node CD4 T cells in muMT(-/-) NOD mice as compared with that of wild-type counterparts, a deficiency that is correlated with an exaggerated CD4 T cell:APC ratio in lymph nodes of muMT(-/-) NOD mice. This feature points to an insufficient availability of APC costimulation on a per T cell basis, resulting in impaired CD4 T cell activation in lymph nodes of muMT(-/-) NOD mice. In accordance with these findings, an islet-reactive CD4 T cell clonotype undergoes suboptimal activation in pancreatic lymph nodes of muMT(-/-) NOD recipients. Overall, the present study indicates that B cells in the pancreatic lymph node microenvironment are critical in overcoming a checkpoint involving the provision of optimal costimulation to islet-reactive NOD CD4 T cells.

Induction of tolerance by intrathymic inoculation of alloantigen

The induction of donor-specific unresponsiveness constitutes the most desirable means of securing long-term graft survival, as it would spare the recipient from the deleterious effects of global immunosuppression. Based on recent insights into the factors controlling both intrathymic and extrathymic clonal deletion or inactivation of T cells, this objective can potentially be accomplished by the direct inoculation of the thymus with alloantigen to modulate T cell development at both the thymic and post-thymic level.

Hepatosplenic gamma-delta T-cell lymphoma as a late-onset posttransplant lymphoproliferative disorder in renal transplant recipients

We report 2 cases of renal transplant recipients in whom hepatosplenic gamma-delta T-cell lymphoma (gamma-delta HSTCL) developed 5 and 10 years after transplantation. Both patients had marked hepatosplenomegaly, B symptoms (weight loss, fever, and night sweats), and abnormal peripheral blood findings, including anemia in both, thrombocytopenia and leukoerythroblastic changes in 1, and leukocytosis in the other. Markedly atypical lymphoid infiltrate of intermediate to large cells was observed in the spleen, liver, and bone marrow. The malignant cells showed typical immunophenotype of gamma-delta T cells (CD2+, CD3+, CD4-, CD8-, CD7+, gamma-delta T-cell receptor-positive, and alpha-beta T-cell receptor-negative) with clonal T-cell receptor gene rearrangement and were of the V-delta-1 subset. In addition, the cells contained a cytolytic granule-associated protein, TIA-1, and Fas ligand, indicating cytotoxic T-cell differentiation. The malignant T cells in both cases were of host tissue origin. Both cases were negative for Epstein-Barr virus genome using Southern blot analysis. The patients did not respond to reduction of immunosuppression. Despite initial response to chemotherapy, both patients died within 6 months of diagnosis. Our findings indicate that gamma-delta HSTCL can occur as a late complication in transplant recipients.

Impaired CD4 T cell activation due to reliance upon B cell-mediated costimulation in nonobese diabetic (NOD) mice

Diabetes in nonobese diabetic (NOD) mice results from the activation of I-A(g7)-restricted, islet-reactive T cells. This study delineates several characteristics of NOD CD4 T cell activation, which, independent of I-A(g7), are likely to promote a dysregulated state of peripheral T cell tolerance. NOD CD4 T cell activation was found to be resistant to antigenic stimulation via the TCR complex, using the progression of cell division as a measure. The extent of NOD CD4 T cell division was highly sensitive to changes in Ag ligand density. Moreover, even upon maximal TCR complex-mediated stimulation, NOD CD4 T cell division prematurely terminated. Maximally stimulated NOD CD4 T cells failed to achieve the threshold number of division cycles required for optimal susceptibility to activation-induced death, a critical mechanism for the regulation of peripheral T cell tolerance. Importantly, these aberrant activation characteristics were not T cell-intrinsic but resulted from reliance on B cell costimulatory function in NOD mice. Costimulation delivered by nonautoimmune strain APCs normalized NOD CD4 T cell division and the extent of activation-induced death. Thus, by disrupting the progression of CD4 T cell division, polarization of APC costimulatory function to the B cell compartment could allow the persistence and activation of diabetogenic cells in NOD mice.

Simultaneous thoracic and abdominal transplantation: can we justify two organs for one recipient?

Simultaneous thoracic and abdominal (STA) transplantation is controversial because two organs are allocated to a single individual. We studied wait-list urgency, and whether transplantation led to successful outcomes. Candidates and recipients for heart-kidney (SHK), heart-liver (SHLi), lung-liver (SLuLi) and lung-kidney (SLuK) were identified through the United Network for Organ Sharing (UNOS) and outcomes were compared to single-organ transplantation. Since 1987, there were 1801 STA candidates and 836 recipients. Wait-list survival at 1- and 3 years for SHK (67.4%, 40.8%; N = 1420), SHLi (65.7%, 43.6%; N = 218) and SLuLi (65.7%, 41.0%; N = 122), was lower than controls (p < 0.001), whereas for SLuK (65.0%, 51.6%; N = 41) it was comparable (p = 0.34). All STA groups demonstrated similar 1- and 5 years posttransplant survival to thoracic controls. Compared to abdominal controls, 1- and 5 years posttransplant survival in SHK (85.3%, 74.0%; N = 684), SLuLi (75.5%, 59.0%; N= 42) and SLuK (66.7%, 55.6%; N = 18) was decreased (p < 0.01), but SHLi (85.9%, 74.3%; N = 92) was comparable (p = 0.81). In summary, STA candidates had greater risk of wait-list mortality compared to single-organ candidates. STA outcomes were similar to thoracic transplantation; however, outcomes were similar to abdominal transplantation for SHLi only. Although select patients benefit from STA, risk-exposure variables for decreased survival should be identified, aiming to eliminate futile transplantation.

Treatment of lymphocele in renal allograft recipients

Retroperitoneal lymphoceles developed in 12 renal allograft recipients during the last nine years. The interval between transplantation and the development of symptoms averaged seven months. The specific syndrome suggesting the presence of a lymphocele included lower abdominal swelling, weight gain, and, occasionally, fever without an obvious source of infection. Although these symptoms mimicked allograft rejection, diagnosis was easily made by ultrasound and intravenous pyelogram. Surgical marsupialization of the lymphocele with drainage into the peritoneal cavity proved to be an effective treatment.