Regulation of autoimmunity and donor cell engraftment by recipient Lyt-2+ cells during the graft-versus-host reaction.

When lymphocytes from DBA/2 mice are transferred to (C57BL X DBA/2)F1 (BDF1) mice, the ensuing graft-vs.-host reaction (GVHR) causes an autoimmune illness resembling human SLE. To examine the role of recipient T cells in this process, BDF1 mice were depleted of L3T4+ or Lyt-2+ cells by thymectomy followed by treatment with mAbs to L3T4 or Lyt-2. This produced sustained depletion of these T cell subsets. Subsequent grafting with parental DBA/2 lymphocytes produced autoimmune disease in mice depleted of L3T4+ cells and controls but not in mice depleted of Lyt-2+ cells. Analysis of blood lymphocytes 4 wk after donor cell transfer demonstrated that BDF1 recipients depleted of Lyt-2+ cells were virtually repopulated with donor T lymphocytes, compared with less than or equal to 35% donor cell engraftment in all other groups. Thus, recipient Lyt-2+ cells influence both host cell engraftment and autoimmunity during the parent-into-F1 GVHR

Splenectomy and Thymectomy in Human Renal Homotransplantation

Five patients with terminal renal failure have been treated with renal homografts. Total body irradiation and cytotoxic drugs were used to prevent rejection. In addition, the thymus and spleen were surgically removed prior to the homotransplantation. Four of the 5 patients are alive with good renal function after 105 to 198 days. The role of thymectomy and splenectomy in conditioning patients for the receipt of homografts is highly speculative at present. However, the early success rate in this group of patients exceeds that generally attained with renal homografts, and appears to justify further clinical evaluation of this approach under carefully controlled experimental conditions. The data are insufficient to allow a recommendation for the general use of these adjuvant procedures. © 1963, SAGE Publications. All rights reserved

Controversies concerning thymus-derived regulatory T cells: fundamental issues and a new perspective

Thymus-derived regulatory T cells (Tregs) are considered to be a distinct T-cell lineage that is genetically programmed and specialised for immunosuppression. This perspective is based on the key evidence that CD25(+) Tregs emigrate to neonatal spleen a few days later than other T cells and that thymectomy of 3-day-old mice depletes Tregs only, causing autoimmune diseases. Although widely believed, the evidence has never been reproduced as originally reported, and some studies indicate that Tregs exist in neonates. Thus we examine the consequences of the controversial evidence, revisit the fundamental issues of Tregs and thereby reveal the overlooked relationship of T-cell activation and Foxp3-mediated control of the T-cell system. Here we provide a new model of Tregs and Foxp3, a feedback control perspective, which views Tregs as a component of the system that controls T-cell activation, rather than as a distinct genetically programmed lineage. This perspective provides new insights into the roles of self-reactivity, T cell–antigen-presenting cell interaction and T-cell activation in Foxp3-mediated immune regulation

Thymoma with Myasthenia Gravis in Adolescent

Thymomas are exceedingly rare in the first 20 years of life, Thymic lesions comprise approximately 2–3% of all pediatric mediastinal tumors and include thymic cysts, hyperplasia, carcinoma, and thymomas. Fewer than 30 cases in children have been described in the literature. Thymomas in adults are commonly associated with other diseases, the most frequent being myasthenia gravis. However, this association has been rarely reported in childhood. These tumors are typically aggressive, with poor outcomes. We report a case of thymoma associated with myasthenia gravis in a 16-year-old girl and review the literature

Indirect induction of radiation lymphomas in mice. Evidence for a novel, transmissible leukemogen.

The transmission of a lymphomagenic agent(s) from the bone marrow of irradiated mice to thymic target cells has been demonstrated by: (a) the induction of T cell lymphomas in nonirradiated thymic grafts implanted in irradiated, Thy-l-congenic mice, (b) the induction of T cell lymphomas of host origin in mice infused with bone marrow from irradiated, Thy-l-congenic donors. The latter procedure also yields an appreciable number of pre-B cell lymphomas of uncertain origin. The results confirm Kaplan's theory that radiation induces thymic lymphomas in mice by an indirect mechanism. However, the previously described radiation leukemia virus is clearly not involved in the majority of transferred lymphomas. We propose that the mediating agent in radiation lymphomagenesis is a novel, transmissible agent induced in the bone marrow, but exerting its transforming activity on cells in the thymus. The nature and mode of action of the agent are under investigation

Thymoma metastatic to liver and pancreas: case report and review of the literature

A 71-year-old man presented with a thymic mass involving the superior vena cava. A mediastinoscopical biopsy initially suggested a diagnosis of type A thymoma. After neoadjuvant chemotherapy, the patient underwent en-bloc thymectomy and vascular resection for a pathology-confirmed type B3 thymoma involving the superior vena cava, the left brachiocephalic vein and the distal part of the right brachiocephalic vein. Adjuvant radiotherapy was administered. Two years after the primary surgery, abdominal computed tomography (CT) and whole body fluorodeoxyglucose (18-FDG) positron emission tomography (PET) scans showed a single hepatic lesion that was treated with wedge liver resection. Pathological examination confirmed metastatic type B3 thymoma. Almost 4 years later, abdominal CT and 18-FDG PET revealed a 2.9-cm solid mass involving the body of the pancreas. Distal pancreatectomy with lymph node dissection was performed. Pathological examination showed a pancreatic metastasis from a type B3 thymoma, without lymph node involvement. The patient is alive and free of disease 6 months after the pancreatectomy (68 months after the initial thymectomy surgery). Intra-abdominal recurrence and pancreatic metastases are very uncommon manifestations of thymoma, but this event should be kept in mind when an abdominal mass is seen during follow-up

Malignant lymphomas in transplantation patients: a review of the world experience.

Malignant lymphomas developed in 9 renal homograft recipients treated at widely separated transplantation centers. The development of these tumors appears to be an indirect complication of organ transplantation and/or the measures taken to prevent rejection. A further complication may be an increased incidence of epithelial tumors. It also seems likely that immune paralysis may accelerate the growth of metastases