T cells with dual antigen specificity in T cell receptor transgenic mice rejecting allografts

Allelic exclusion of T cell receptor (TCR) genes is incomplete: a significant percentage (10-30%) of normal human and mouse peripheral T cells express two surface TCR alpha chains, and a small percentage of peripheral human T cells have been reported to express two surface TCR beta chains. A proportion of thymocytes in TCR transgenic mice rearrange endogenous T cell receptor genes, and peripheral T cells with two TCR alpha chains, transgenic and endogenous, have been reported. T cell clones with more than a single TCR heterodimer on their surface might be expected to show specificity for more than one cognate antigen: we report here a T cell clone with dual antigen specificity, isolated from an F5 TCR influenza nucleoprotein (NP 366-374/Db)-specific transgenic female mouse which had rejected an H-2-matched male skin graft. It was selected in vitro by stimulation with male H-2b spleen cells in the absence of the NP366-374 peptide but has specificity for both H-Y/Db and NP366-374. This contrasted with the single NP366-374/Db specificity shown by a control clone isolated from a Rag1-/- F5 mouse. The dual antigen specificity was associated with the rearrangement of endogenous TCR genes and cell surface expression of these as well as the TCR transgene.

Identification of a mouse male-specific transplantation antigen, H-Y

The male-specific transplantation antigen, H-Y, causes rejection of male tissue grafts by genotypically identical female mice and contributes to the rejection of human leukocyte antigen-matched male organ grafts by human females. Although first recognized 40 years ago, the identity of H-Y has remained elusive. T cells detect several distinct H-Y epitopes, and these are probably peptides, derived from intracellular proteins, that are presented at the cell surface with major histocompatibility complex (MHC) molecules. In the mouse, the gene(s) controlling H-Y expression (Hya) are located on the short arm of the Y chromosome between the zinc-finger genes Zfy-1 and Zfy-2. We have recently identified Smcy, a ubiquitously expressed gene, in this region and its X-chromosome homologue, Smcx. Here we report that Smcy encodes an H-YKk epitope that is defined by the octamer peptide TENSGKDI: no similar peptide is found in Smcx. These findings provide a genetic basis for the antigenic difference between males and females that contributes towards a tissue transplant rejection response.

Immune responsiveness in mutant mice lacking T-cell receptor alpha beta+ cells

Immune responses of mice with T-cell receptor (TCR)gamma delta+ T cells but lacking TCR alpha beta+ cells because of a disruption in the TCR alpha gene, were analysed against alloantigens, soluble protein antigen, killed Mycobacterium tuberculosis and exogenous superantigen. Rejection of skin allografts mismatched for classical major histocompatibility complex (MHC) plus multiple minor H antigens was virtually abrogated but the presence of mismatched Qa-1 non-classical MHC antigens on donor tissue resulted in a significant proportion of TCR alpha-/- mice rejecting such grafts. In view of the proposed role for gamma delta T cells in mycobacterial responses, and particularly against self- or mycobacterial heat-shock protein HSP 65, we examined these responses in TCR alpha-/- mice. Local responses after immunization were low in lymph nodes and no component of these was directed against mycobacterial HSP 65. However, splenic T cells from mutant mice responded strongly to either purified protein derivative (PPD) or M. tuberculosis. Our findings indicate that TCR alpha-/- mice are selectively compromised: while responses to (undefined) mycobacterial antigens were substantial, responses to some other target antigens such as MHC alloantigens and HSP 65, believed to be preferentially recognized by gamma delta receptors, were poor or absent. However, the fact that the mutant mice more readily rejected allografts that are mismatched for the non-classical MHC antigen Qa-1 in addition to classical MHC and minor-H incompatibility, indicates that in some mice the residual immune response, presumed to be by gamma delta cells, is sufficient to cause skin graft rejection and that recognition of non-classical MHC antigens may play an important part in the response.

Angiogenesis and vascularization of murine pancreatic islet isografts

Although the microvascular endothelium has been identified as the primary target site for the initiation of pancreatic islet graft rejection, little is known of the microvascular and cellular mechanisms involved, partly due to the lack of adequate models. Herein, we present a model for the in vivo assessment of the microcirculation of pancreatic islet grafts in mice. Isolated islets of Langerhans from immunocompetent hairless mice and immunoincompetent athymic nude mice were transplanted syngeneically into a specially designed dorsal skinfold chamber mounted on nondiabetic recipients. The islets' microcirculation was visualized by means of intravital fluorescence microscopy, and microcirculatory parameters were quantitatively analysed over a period of 14 days in the awake animal. Between day 2 and 4 after transplantation 84% (31/37; hairless mice) and 69% (36/52; nude mice) of the islet grafts revealed capillary sprouts and formation of new microvessels. On day 6, these sprouts were found interconnected, and red blood cell movement within the newly formed microvascular network was observed. The process of angiogenesis and revascularization was completed within 10 days after transplantation yielding a glomerulus-like network of capillaries as known for pancreatic islets in situ. Functional capillary density of the islet grafts ranged between 650 and 700 cm-1 in both hairless and nude mice. Within the islets' microvessels neither accumulation of leukocytes nor leukocyte-endothelial cell interaction was observed, indicating the lack of rejection and inflammation in these syngeneic islet grafts. We propose that this model provides a wide spectrum of promising experimental approaches for the study of microcirculatory and cellular mechanisms in free pancreatic islet transplantation.

Aspartate at position 57 of nonobese diabetic I-Ag7 beta-chain diminishes the spontaneous incidence of insulin-dependent diabetes mellitus

MHC class II genes have been shown to influence the development of the autoimmune disease insulin-dependent diabetes mellitus (IDDM) in the nonobese diabetic (NOD) mouse. In human IDDM it has been suggested that the presence of an aspartate at position 57 of the DQ beta-chain might be important in determining resistance to development of IDDM. The involvement of MHC class II genes in IDDM was investigated through the introduction of MHC encoding transgenes. We show that introduction of a mutated I-Ag7 Ab gene which encodes an aspartate at position 57 reduces the incidence of IDDM but does not prevent insulitis, sialadenitis, or the development of insulin and nuclear autoantibodies.

Aspartate at position 57 of nonobese diabetic I-Ag7 beta-chain diminishes the spontaneous incidence of insulin-dependent diabetes mellitus

MHC class II genes have been shown to influence the development of the autoimmune disease insulin-dependent diabetes mellitus (IDDM) in the nonobese diabetic (NOD) mouse. In human IDDM it has been suggested that the presence of an aspartate at position 57 of the DQ beta-chain might be important in determining resistance to development of IDDM. The involvement of MHC class II genes in IDDM was investigated through the introduction of MHC encoding transgenes. We show that introduction of a mutated I-Ag7 Ab gene which encodes an aspartate at position 57 reduces the incidence of IDDM but does not prevent insulitis, sialadenitis, or the development of insulin and nuclear autoantibodies.

Stressors and close relationships during childhood and dissociative experiences in survivors of sexual abuse among inpatient psychiatric women

The purpose of this study was to examine which childhood events were associated with more extensive use of adult dissociative states in 90 female inpatients with histories of sexual abuse. The study found that childhood stressors of maltreatment (physical neglect, witnessing sexual abuse, and witnessing physical abuse) were associated with higher levels of dissociative symptoms. In contrast, childhood stressors of loss (parental separation and death of a close relative) were not related to increased severity of dissociative symptoms. The study also demonstrated that a close relationship with either a parent, sibling, extraparental adult, or friend did not have a mediating effect on the degree of adult dissociative symptoms. Directions for future research are presented.

Tolerance in TCR/cognate antigen double-transgenic mice mediated by incomplete thymic deletion and peripheral receptor downregulation

Influenza nucleoprotein (NP)-specific T-cell receptor transgenic mice (F5) were crossed with transgenic mice expressing the cognate antigenic protein under the control of the H-2Kb promoter. Double-transgenic mice show negative selection of thymocytes at the CD4+8+TCRlo to CD4+8+TCRhi transition stage. A few CD8+ T cells, however, escape clonal deletion, and in the peripheral lymphoid organs of these mice, they exhibit low levels of the transgenic receptor and upregulated levels of the CD44 memory marker. Such cells do not proliferate upon exposure to antigen stimulation in vivo or ex vivo, however, they can develop low but detectable levels of antigen-specific cytotoxic function after stimulation in vitro in the presence of IL-2.

Multi-modality megatherapy with [131I]meta-iodobenzylguanidine, high dose melphalan and total body irradiation with bone marrow rescue: feasibility study of a new strategy for advanced neuroblastoma

New therapeutic approaches are needed for advanced neuroblastoma as few patients are currently curable. We describe an innovative strategy combining [131I]meta-iodobenzylguanidine ([131I]mIBG) therapy with high dose chemotherapy and total body irradiation. The aim of combining these treatments is to overcome the specific limitations of each when used alone to maximise killing of neuroblastoma cells. Five children received combined therapy with [131I]mIBG followed by high dose melphalan and fractionated total body irradiation. Autologous bone marrow transplantation was undertaken in 3 patients and allogeneic in 2 patients. One patient received additional localised radiotherapy to residual bulk disease. One patient is alive without relapse 32 months after treatment. 4 patients relapsed after remissions of 9, 10, 14 and 21 months. These results indicate that this combined modality approach is feasible and safe, but further evaluation is necessary to establish whether it has advantages over conventional megatherapy using melphalan alone.

Non-diabetogenic insulitis in NOD<-->B10.GD allophenic mice in spite of permissive class I MHC antigens

Allophenic mice (embryo aggregation mouse chimeras) enable us to dissect the process of spontaneous autoimmunity under physiological conditions. Our previous experiments showed that the autoimmune process in allophenic mice of the NOD<-->C57B1/6 strain combination does not progress from insulitis to diabetes. One possible explanation for this protection is that H-2 Kd-restricted CD8+ T cells kill only NOD beta cells (Kd,Db) in the chimeric islets, while the B6 beta cells (Kb,Db) are spared from destruction. To test this hypothesis we analysed 22 NOD<-->B10.GD chimeras in which the class I MHC are shared by both parental strains. Therefore all the beta cells in these chimeras express H-2 Kd molecules. Ten allophenic mice were killed at 7 weeks and studied for early pathology. No evidence for intra-islet infiltration was obtained at this age, suggesting that the autoimmune process in NOD<-->B10.GD chimeras is slower than in NOD mice. Twelve chimeras were followed up for 1 year for disease development and all failed to progress to full-blown diabetes, despite the occurrence of intra-insulitis in six out of 12 mice. The lack of disease in NOD<-->B10.GD chimeras demonstrates that class I MHC chimerism does not account for diabetes resistance in NOD-allophenic mice.

Deletion mapping by immunoselection against the H-Y histocompatibility antigen further resolves the Sxra region of the mouse Y chromosome and reveals complexity of the Hya locus

A genetic map of the mammalian Y chromosome cannot be produced by standard Mendelian methods because the Y does not participate in meiotic exchange over the majority of its length. However, deletion mapping of the mouse Y chromosome is facilitated by the fact that its short arm carries the histocompatibility-Y (Hya) locus. This locus encodes male-specific (H-Y) antigens that can be selected against in tissue culture by the technique of immunoselection. To produce cells carrying deletions, cytotoxic T lymphocytes (CTLs) specific for H-Y antigens were cocultured with a lymphoblastoid cell line derived from a mouse carrying the portion of the short arm defined by the Sxra translocation on the distal end of its X chromosome. H-Y antigen-loss variant cells that contained Y-specific deletions were identified. Molecular, karyotypic, and immunological analysis of the deletion variants allowed us to define up to 16 ordered intervals and suggested an overall organization of Sxra. The analysis also suggests that at least two and up to five distinct loci encode H-Y antigens.

The relationship between characteristics of sexual abuse and dissociative experiences

Childhood sexual abuse has been associated with adult dissociative symptomatology. The purpose of this study was to examine the relationship between specific characteristics of sexual abuse and dissociative experiences in adulthood. Fifty-six female inpatients with a history of physical abuse and severe sexual abuse reported on their history of abuse and dissociative experiences. A logistic regression that controlled for physical revictimization showed that sexual abuse by a greater number of different sex abuse offenders was significantly related to an elevated level of dissociation. In exploring how many sex abuse offenders are associated with dissociative experiences, a logistic regression revealed a significant relationship between four or more sex abuse offenders and greater dissociative symptomatology. The reported age of onset of the sexual abuse was not a significant predictor of dissociation when sexual revictimization was included in the analysis. These findings suggest that severely traumatized patients with a history of multiple sex abuse offenders are highly likely to use dissociation as a primary psychological defense. The implications of the study are discussed.

Resectability of advanced liver tumours in children after combination chemotherapy

Five patients with locally advanced or metastatic liver tumours were treated at the Royal Hospital for Sick Children between 1983 and 1992 by preoperative combination chemotherapy and subsequent complete resection of the residual liver tumour. Chemotherapy was generally well tolerated with few significant adverse effects. Tumour resection was accomplished by lobectomy in three cases and an extended lobectomy in the remaining two. All five children are currently well and free of disease at a mean follow-up of 36 months.

Studies on the thymus of non-obese diabetic (NOD) mice: effect of transgene expression

The non-obese diabetic (NOD) mouse is a good model of insulin-dependent diabetes mellitus. Autoreactive T cells may play a fundamental role in disease initiation in this model, while disregulation of such cells may result from an abnormal thymic microenvironment. Diabetes is prevented in NOD mice by direct introduction of an E alpha d transgene (NOD-E) or a modified I-A beta chain of NOD origin (NOD-PRO or NOD-ASP). To investigate if disease pathology in NOD mice, protection from disease in transgenic NOD-E and NOD-PRO and partial protection from disease in NOD-ASP can be attributed to alterations in the thymic microenvironment, immunohistochemical and flow cytometric analysis of the thymi of these mouse strains was studied. Thymi from NOD and NOD-E mice showed a progressive increase in thymic B-cell percentage from 12 weeks of age. This was accompanied by a concomitant loss in thymic epithelial cells with the appearance of large epithelial-free areas mainly at the corticomedullary junction, which increased in size and number with age and contained the B-cell clusters. Such thymic B cells did not express CD5 and were absent in CBA, NOD-ASP and NOD-PRO mice as were the epithelial cell-free spaces, even at 5 months of age. Therefore the mechanisms of disease protection in the transgenic NOD-E and NOD-ASP/NOD-PRO mice may differ if these thymic abnormalities are related to disease.

Metabolic effects of acute hyperketonaemia in man before and during an hyperinsulinaemic euglycaemic clamp

1. The effects of acutely raising blood ketone body levels to those seen after 72 h of starvation were examined in 10 subjects after an overnight fast. Metabolic rate and respiratory exchange ratio were measured with indirect calorimetry before and during an insulin-glucose clamp. Arteriovenous differences were measured across forearm and subcutaneous abdominal adipose tissue. 2. In response to the clamp the respiratory exchange ratio rose from 0.82 to 0.83 during 3-hydroxybutyrate infusion and from 0.83 to 0.94 during control (saline) infusion (P < 0.001). 3. Forearm glucose uptake at the end of the clamp was 4.02 +/- 0.95 (3-hydroxybutyrate infusion) and 7.09 +/- 1.24 mmol min-1 100 ml-1 forearm (saline infusion). Whole body glucose uptake at the end of the clamp was 72.8 +/- 7.9 (3-hydroxybutyrate infusion) and 51.0 +/- 3.0 (saline infusion) mmol min-1 kg-1 body weight-1. 4. 3-Hydroxybutyrate infusion reduced the baseline abdominal venous-arterialized venous glycerol difference from 84 +/- 28 to 25 +/- 12 mmol/l and the non-esterified fatty acid difference from 0.60 +/- 0.17 to 0.02 +/- 0.09 mmol/l (P < 0.05 versus saline infusion). 5. Hyperketonaemia reduces adipose tissue lipolysis and decreases insulin-mediated forearm glucose uptake. Hyperketonaemia appears to prevent insulin-stimulated glucose oxidation, but does not reduce insulin-mediated glucose storage.

Combination chemotherapy for primitive neuroectodermal and other malignant brain tumours

The toxicity and efficacy of a chemotherapy schedule comprising vincristine and cyclophosphamide, alternating with carboplatin and etoposide, has been assessed in a group of 15 patients with medulloblastoma, supratentorial primitive neuroectodermal tumours (PNET) or other malignant brain tumours. The patients comprised four adults and 11 children. Chemotherapy was given for palliation of recurrent disease (six patients), as an adjuvant to radiotherapy and surgery in five poor prognosis patients, or to delay the need for radiotherapy in four children aged 2 years or less. The treatment was generally well tolerated, with the principal toxicity being myelo-suppression. Among the ten assessable patients, there were six complete responders and one partial, an overall response rate of 70%. Three patients had progressive disease. Responses, although associated with good symptomatic improvement, were short lived, with two patients relapsing while still receiving chemotherapy. Three of four very young children relapsed within 7 months of completing chemotherapy and then received radiotherapy. It is concluded that this schedule merits further evaluation and comparison with more protracted and toxic schedules.

Separation of thymic education from antigen presenting functions of major histocompatibility complex class I molecules

Participation of transmembrane (TM) and glycosyl-phosphatidylinositol (GPI) anchored H-2Db molecules in antigen presentation and thymic selection events was investigated using transgenic mice. Both GPI-Db and TM-Db can efficiently present H-Y antigen, influenza and lymphocytic choriomeningitis virus (LCMV) peptides to primed cytotoxic, H-2Db-restricted T cells. Transgenic mice expressing GPI-Db, although unable to reject TM-Db skin grafts, nevertheless generate secondary CTL responses which can lyse TM-Db-bearing targets, indicating that GPI-Db mice fail to delete all TM-Db-reactive T cells. Furthermore, double-transgenic mice bearing GPI-Db and a T-cell receptor (TcR) for H-2Db+LCMV do not positively select receptor positive, CD8+CD4- T cells. This paradoxical behaviour of GPI-Db molecules suggests that the structural requirements for antigen presentation and thymic selection by class I molecules are different and may explain why GPI-linked class I molecules, such as Qa-2, do not appear to function as restriction elements in vivo.

Deletion of Y chromosome sequences located outside the testis determining region can cause XY female sex reversal

An approach designed to map and generate mutations in the region of the short arm of the mouse Y chromosome, known to be involved in sex determination and spermatogenesis, is described. This relies on homologous Yp-Sxra pairing and asymmetrical exchange which can occur at meiosis in XY males carrying Sxra on their X chromosome. Such exchange potentially generates deficiencies and duplications of Yp or Sxra. Three fertile XY females were found out of about 450 XY offspring from XSxra/Y x XX crosses. In all three, despite evidence for deletion of Y chromosomal material, the Sry locus was intact. Each deletion involved a repeat sequence, Sx1, located at a distance from Sry. Since expression of Sry was affected these results suggest that long range position effects have disrupted Sry action.

Exon-specific northern analysis and rapid amplification of cDNA ends (RACE) reveal that the proximal promoter II (PII) is responsible for aromatase cytochrome P450 (CYP19) expression in human ovary

Estrogens are synthesized from C19 steroids by a unique form of cytochrome P450, aromatase cytochrome P-450 (P-450AROM; the product of the CYP19 gene). We have shown that tissue-specific expression of human P-450AROM is determined, in part, by the use of alternative promoters. Previous methods of analysis for determining the specific 5'-termini of the different transcripts included S1 nuclease protection, primer extension, and Northern analysis. In the present study we have used the RACE procedure (rapid amplification of cDNA ends) to amplify and clone the 5' termini of P-450AROM transcripts expressed in human corpus luteum (CL). Sequencing of the resulting clones supports the results of the previously performed studies. Specifically, the proximal promoter, PII, is the predominant promoter utilized in CL, such that the start of transcription occurs 26 bp downstream of the putative TATA sequence. A minority of the clones possess an alternative 5'-end, namely I.3. Exon-specific Northern analysis confirms that the majority of the P-450AROM transcripts in CL tissue contain sequence specific for promoter II. Similarly, exon-specific Northern analysis indicates that transcripts in human follicles, as well as granulosa cells in culture, contain primarily sequence specific for promoter II.

The effect of bone marrow and thymus chimerism between non-obese diabetic (NOD) and NOD-E transgenic mice, on the expression and prevention of diabetes

The non-obese diabetic (NOD) mouse is an established animal model of the autoimmune disease, insulin-dependent diabetes mellitus (IDDM). The NOD-E mouse is a transgenic mouse which expresses the I-E molecule (absent in NOD mice). Expression of I-E protects these mice from both insulitis and IDDM. We have investigated the possible mechanisms of this protection by constructing bone marrow, and combined bone marrow and thymus chimeras between NOD and NOD-E mice. Our data suggest that thymic epithelium may play no direct role in either protection against, or promotion of, IDDM. Protection from diabetes is provided either by NOD-E donor bone marrow or NOD-E recipient non-thymic radioresistant cells. The means by which protection may be achieved in this system are discussed.

T cell deletion follows chronic antigen specific T cell activation in vivo

Exposure of mice transgenic for a TCR (F5) to cognate peptide antigen results in thymic depletion of CD4+CD8+ cells and expansion and activation of peripheral CD8+ TCR(tg)+ T cells. In the thymus apoptotic DNA ladder is evident as early as 3 h after peptide injection. Long exposure of intact or thymectomized F5 TCR transgenic mice to peptide antigen leads to depletion of most of the peripheral CD8+ T cells bearing the F5 receptor, with the remaining cells having lower levels of transgenic TCR compared with non-treated animals. In the thymus of intact F5 TCR transgenic mice such continuous exposure to antigen results in the reappearance of CD4+CD8+ with lower levels of the transgenic receptor.

Regulation of expression of the CYP11A (P450scc) gene in bovine ovarian luteal cells by forskolin and phorbol esters

This study examines the transcriptional regulation of the bovine CYP11A (P450scc) gene by activators of protein kinase A and protein kinase C in bovine ovarian luteal cells. Cells were transfected with reporter gene constructs containing deletion mutations of the 5'-flanking region of the bovine CYP11A gene linked to the minimal beta-globin gene. A construct containing -118/-101 base pairs of CYP11A sequence retains the same degree of stimulation by forskolin and inhibition by co-treatment with phorbol 12-myristate 13-acetate as larger constructs. This sequence contains two putative binding sites for nuclear proteins, an AP1-like sequence and an overlapping GA box element. Gel shift analysis using nuclear extracts of bovine ovarian luteal cells demonstrated that both the wild-type -118/-101-base pair sequence and a consensus GC box bound Sp1 or Sp1-like proteins. Mutation of the GA box element completely suppressed stimulation by forskolin. Absence of binding using the same mutated sequence correlated with the reporter gene transcription results. Mutation of the AP1-like site had little effect on forskolin induction of phorbol 12-myristate 13-acetate inhibition. These results indicate that both stimulation by forskolin and inhibition by phorbol esters are mediated by the same GA box element, which binds Sp1 or an Sp1-like protein.