Prevalence and factors associated with chronic kidney disease and end-stage renal disease in HIV-1-infected Asian patients in Tokyo

This single-center cross-sectional study determined the prevalence and factors associated with chronic kidney disease (CKD) and end-stage renal disease (ESRD) in HIV-1-infected Asian patients at the largest HIV clinic in Japan. HIV-1-infected patients who visited the clinic between September and December 2016 were analyzed. CKD was defined as estimated glomerular filtration rate of <60 ml/min/1.73 m² or proteinuria ≥1+, observed at least over three months. A logistic regression model was used to estimate the effects of various variables on CKD. The study included 1,990 patients; with 97% Asians, 34% aged of ≥50 years, and 94% had HIV-1 load <50 copies/ml. The median time from HIV-1 diagnosis to study enrollment and duration of ART were 9.1 years (IQR4.8–14.2) and 7.35 years (IQR3.28–12), respectively. CKD and ESRD were diagnosed in 256 (13%) and 9 (0.5%) patients, respectively. The prevalence of CKD was 18.6% for age 50–59, 28.5% for 60–69, and 47% for over 70. Older age, heavier body weight, diabetes mellitus, hypertension, and longer duration of ART, but not duration of TDF exposure, were associated with CKD. The traditional risk factors, rather than HIV-1-related variables, were associated with CKD, suggesting the importance of management of such comorbidities in maintenance of renal function.

Involvement of brown adipose tissue in subcutaneous fat necrosis of the newborn

BACKGROUND

Subcutaneous fat necrosis (SCFN) of the newborn is a rare condition that manifests within days after birth. The interscapular region, axillae and shoulders are the most commonly affected sites, corresponding to anatomic sites of brown adipose tissue (BAT) in newborns.

OBJECTIVE

We postulated a specific involvement of BAT in SCFN and searched for brown adipocytes at affected sites.

METHODS

Biopsy specimens were immunostained with antibodies against uncoupling protein 1 (UCP-1) and examined by electron microscopy. We also examined BAT by (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography and computed tomography (PET-CT) scanning.

RESULTS

A few cells in biopsy specimens from two patients bound antibodies against UCP-1, and brown adipocytes were detected at several stages of degeneration. PET-CT scans revealed lower uptake of (18)F-FDG at major sites of SCFN.

CONCLUSION

SCFN and BAT can be found at the same sites, suggesting a pathophysiological connection.

Root of the small-bowel mesentery: correlative anatomy and CT features of pathologic conditions

The root of the small-bowel mesentery (SBM) is an important peritoneal fold that is contiguous to other peritoneal ligaments and mesocolons. Several pathologic conditions can occur in the SBM itself, and diseases that spread through the connections from adjacent organs frequently involve it. The root of the SBM is contiguous to the hepatoduodenal ligament around the superior mesenteric vein (SMV) and contiguous to the right side of the transverse mesocolon around the gastrocolic trunk. The inferior mesenteric vein, which is a landmark of the descending mesocolon, runs along the left side of the root of the SBM. Malignant neoplasms can spread to the SBM by means of direct extension, extension along the neural plexus, extension along neighboring ligaments, or extension along lymphatic vessels. Inflammatory conditions such as pancreatitis and perforation of a jejunal diverticulum can also spread to the SBM. Anomalies that can occur in the SBM include rotation anomalies and internal hernia. Vascular lesions of the SBM include thrombosis of the superior mesenteric artery (SMA), acute SMV thrombosis, SMA dissection, arterioportal fistula, and portal venous gas. Other pathologic conditions that can occur in the SBM are edema or congestion, mesenteric tear, mesenteric panniculitis, and tumors or tumorlike lesions.

An immature rat lymphocyte marker CD157: striking differences in the expression between mice and rats

We have established a novel monoclonal antibody that recognises mouse and rat CD157, and uncovered striking differences in both the level and stage of expression of this antigen in the primary lymphoid organs between these two species. Unlike mouse, the majority of rat thymocytes express CD 157. SHR and WKY rats were the exception, having unusually low levels (similar to those of the mouse) of these cells. However, in both species, a subset of CD3- CD4- CD8- thymocytes exhibited high levels of CD157. Surprisingly, these CD157high cells temporarily upregulated MHC class I molecules in both species. Furthermore, a third of CD157high rat thymocytes were CD45RC+, a marker found on immature thymocytes with regenerative capacity. Examination of the bone marrow lymphoid population shows that the expression of rat CD157 is largely observed at the CD45R+ IgM- pre-B-II cell stage, and unlike mouse, extension of expression into the IgM+ immature B cell stage was marginal. Similar to CD157high immature thymocytes, these immature B cells also expressed high levels of MHC class I. With the exception of the LEC, SHR and WKY rat strains, which have three- to four-fold less CD157+ bone marrow myeloid cells, percentages of these cells are similar between these two species. Thus, marked differences in the level and stage(s) of CD157 expression on lymphoid cells in mouse and rat indicate that CD157 may not, as previously thought, have a direct role in T or B cell differentiation.

Leiomyoma of the parapharyngeal space

A rare case of leiomyoma of the prestyloid parapharyngeal space is reported together with computed tomographic and magnetic resonance imaging findings. The tumor appeared as a well-circumscribed ovoid mass with some calcifications and lobulations. Because the attenuation, signal intensity, and shape of the mass were not specific and were similar to those of a pleomorhic adenoma, the most common tumor of the prestyloid parapharyngeal space, radiological differentiation of leiomyoma from pleomorphic adenoma of the prestyloid parapharyngeal space was difficult.

Pelvic extension of retroperitoneal fluid: analysis in vivo

OBJECTIVE

The purposes of this study were to describe the pathway of fluid flow from the retroperitoneal space into the pelvic extraperitoneal space on CT in vivo, to clarify the relation between its occurrence and the site or amount of retroperitoneal fluid, and to delineate the anatomic relation between the retroperitoneal spaces and the pelvic extraperitoneal space.

MATERIALS AND METHODS

We reviewed the CT scans of 37 patients with retroperitoneal fluid collections. Patients who had undergone pelvic laparotomy and patients who had either fascial thickening alone or fluid within muscle (such as the psoas muscle or iliac muscle) alone were excluded.

RESULTS

Fluid extension into the pelvic extraperitoneal space was seen in six patients (16%). Extension by the infrarenal extraperitoneal space was seen in all six of these patients, but extension by properitoneal fat was seen in only one of the six patients. In patients with large amounts of fluid in the infrarenal extraperitoneal space, we frequently saw extension into the pelvic extraperitoneal space. Extension of pancreatic fluid into the infrarenal extraperitoneal space occurred in only 15% of the 37 patients. However, it occurred in both patients with ruptured abdominal aortic aneurysms. Three pathways from the infrarenal extraperitoneal space into the pelvic extraperitoneal space were seen: extension dorsally medial to the iliac vessels (n = 6), extension dorsally lateral to the iliac vessels (n = 1), and extension medially into the prevesical space (n = 2). Coexistence of two of these three pathways was seen in three patients.

CONCLUSION

In vivo, extension of retroperitoneal fluid into the pelvic extraperitoneal space is not rare and occurs more often by the infrarenal extraperitoneal space than by properitoneal fat. Extension of retroperitoneal fluid to the infrarenal extraperitoneal space can be attributed less frequently to sources distant to the pelvic cavity such as pancreatic fluid. Such extension often derives from sources that can produce large amounts of retroperitoneal fluid such as ruptured abdominal aortic aneurysms. Of the three pathways from the infrarenal extraperitoneal space to the pelvic extraperitoneal space, dorsal extension medial to the iliac vessels is the most common, and multiple pathways often coexist.

Appendiceal abscess mimicking infected urachal cyst in a child with intestinal malrotation

An appendiceal abscess with intestinal malrotation can occur anywhere in the abdomen, not only in the right lower quadrant. We report a case presenting a midline mass of the lower abdomen whose computed tomography (CT) and ultrasonography (US) findings mimicked a urachal abscess. A retrospective review of CT findings led to the correct diagnosis by showing malposition of the ascending colon.

Adenoid cystic carcinoma of the external auditory canal: correlation between histological features and MRI appearances

A rare case of adenoid cystic carcinoma of the external auditory canal with magnetic resonance imaging appearances is reported. Both T1 weighted and T2 weighted MR images showed the tumour as a hypointense mass, although there was marked contrast enhancement. Microscopic examination of the resected tumour showed a preponderance of solid tumour cell nests. According to previous reports, these pathological and radiological findings indicate a poor prognosis.

TCR V alpha chain expression influences reactivity to the hapten TNP

We have recently demonstrated a remarkable selection of in vitro cultivated, TNP-specific polyclonal T cell lines for the expression of a TCR beta chain encoded by the V beta 8.2 gene. The goal of the present study was to analyse V alpha usage in V beta 8.2 T cells responsive to TNP, using TNP-specific T cell lines derived from three common strains of mice, as well as from V beta 8.2 transgenic mice. Results indicate that in vitro TNP stimulation of T cells from TNP-immune mice results in significant skewing of V alpha usage among responding V beta 8.2+ T cells, with overexpression observed for V alpha 3.2 and V alpha 8. These results indicate that V alpha expression influences recognition of TNP by T cells, and suggest that the hapten TNP might be recognized like typical peptide antigens by combinatorial TCR alpha and beta contact sites.

Identification of murine T cells reactive with the bacterial superantigen Yersinia pseudotuberculosis-derived mitogen (YPM) and factors involved in YPM-induced toxicity in mice

We previously reported that Yersinia pseudotuberculosis-derived mitogen (YPM) acts as a superantigen to human T cells. In this study, we assessed the superantigenicity and toxicity of YPM using murine experimental models. YPM activated T cells to produce interleukin-2 in a major histocompatibility complex class II molecule-dependent manner. The T-cell blasts induced by YPM expressed T-cell receptor (TCR) beta-chain variable region (Vbeta)7, Vbeta8.1, Vbeta8.2 and Vbeta8.3. The injection of YPM into mice pre-sensitized with D-galactosamine induced lethal shock. This shock was blocked by the injection of monoclonal antibodies (mAbs) to CD4, TCR Vbeta7 plus Vbeta8, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), but not by injection to CD8 or unrelated Vbeta. These results indicate that YPM-induced shock requires the presence of CD4+ T cells bearing TCR Vbeta7 and Vbeta8, and that endogenous TNF-alpha and IFN-gamma mediate the lethal effects.

Percutaneous retrieval of intracardiopulmonary artery metallic needle (Kirschner's wire): a case report

We report a case of successful percutaneous retrieval of a broken Kirschner's wire that had entered the venous system and the right atrium and later migrated to the left pulmonary artery. The management of a long, rigid, nail-like foreign body within the heart and/or the pulmonary artery is discussed.

[Recent progress in superantigen research]

In 1993 there was substantial progress in superantigen research. The following are the main achievements. (i) The life cycle of an exogenous mouse mammary tumor virus, MMTV (SW), has been clearly eluciated. (ii) X-ray crystallography of toxic shock syndrome toxin 1 has been completed. (iii) The involvement of a superantigen encoded by an endogenous mouse mammary tumor virus, Mtv-51, in the development of a B cell lymphoma has been shown in SJL mice. However, there are many unsolved questions. For example, (i) are there endogenous superantigens in man? (ii) is there any role for superantigens in the development of autoimmunity? (iii) what is the three dimensional structure of superantigens encoded by mouse mammary tumor viruses? In the near future superantigens will be exploited for therapeutic purposes in the area of autoimmunity and cancer.

Family characteristics and offspring growth in various countries. I. Frequency of various family types in Bulgaria, Japan, Korea, Mexico and Poland

9936 families were analyzed from Bulgaria, Japan, Korea, Mexico, and Poland. A factor analysis revealed four factors: culture (F1), income (F2), genetics (F3), and family and apartment size (F4). Family types we coded as 1 if below the median and 2 if above the median. The most frequent types were represented by 1122, 2221, and 2211 (frequency 8.7-8.0%), and the least frequent by 1221 and 2111 (frequency 4.2-4.3%). Some similarity with respect to family types were found between populations: from Polish regions with heavy industry and seaside regions; from Polish towns under industrialization and from Mexico; from the Polish medium-size town of Lublin and Bulgarian towns; from Polish villages; from Polish mountain areas and north-eastern towns; from Korea; from Japan; from Polish cities.

T cell receptor V alpha-V beta combinatorial selection in the expressed T cell repertoire

This study has evaluated whether preferential pairing occurs between TCR alpha- and beta-chains expressing specific V alpha and V beta gene products in the mature peripheral T cell population, as a result of either thymic selection or of structural constraints on chain pairing. The association of specific V alpha products with specific V beta products on individual T cells was found, in multiple instances, to be highly selective. Moreover, patterns of preferential V alpha-V beta association were highly strain-specific and were independently expressed in CD4+ and CD8+ T cell subsets. Although these findings do not exclude the possibility that structural constraints may limit V alpha-V beta pairing in other instances, they indicate that the observed instances of skewed expression are not caused by structural constraints in chain pairing. Rather, they suggest that strain-specific selective events alter the expressed V alpha V beta repertoire as a result of recognition of self or environmental Ag during T cell repertoire selection.

T cell receptor V alpha-V beta combinatorial selection in the expressed T cell repertoire

This study has evaluated whether preferential pairing occurs between TCR alpha- and beta-chains expressing specific V alpha and V beta gene products in the mature peripheral T cell population, as a result of either thymic selection or of structural constraints on chain pairing. The association of specific V alpha products with specific V beta products on individual T cells was found, in multiple instances, to be highly selective. Moreover, patterns of preferential V alpha-V beta association were highly strain-specific and were independently expressed in CD4+ and CD8+ T cell subsets. Although these findings do not exclude the possibility that structural constraints may limit V alpha-V beta pairing in other instances, they indicate that the observed instances of skewed expression are not caused by structural constraints in chain pairing. Rather, they suggest that strain-specific selective events alter the expressed V alpha V beta repertoire as a result of recognition of self or environmental Ag during T cell repertoire selection.

Influence of viral superantigens on V beta- and V alpha-specific positive and negative selection

In mice, V beta-specific negative selection is mediated by a number of superantigens encoded by various mouse mammary tumor viruses. We have identified Mtv-3, Mtv-27, Mtv-44, Mtv-8, Mtv-9, Mtv-11, and MMTV(D2.GD), and have confirmed Mtv-1. Although specificities of superantigens correlate well with sequences of their carboxy terminal regions, Mtv-44 appears to be an exception: the product is specific for V beta 3, V beta 6, V beta 8.1, and V beta 9. It remains to be determined whether Mtv-44 produces one or two different superantigens to exhibit this specificity. V beta 5+ T-cell deletion is induced by two groups of superantigens: V beta 3-specific superantigens encoded by Mtv-1, Mtv-3, Mtv-6, Mtv-13, Mtv-27, and Mtv-44, and V beta 11-specific superantigens encoded by Mtv-8, Mtv-9, and Mtv-11. Furthermore, these V beta 3-specific superantigens are also specific for V beta 17a(cz). In contrast, V beta-specific positive selection and V alpha-specific positive and negative selection do not seem to involve non-H-2 (super)antigens, although their involvement can not be excluded. In the near future, superantigens, powerful modulators of T-cell functions, will be exploited for clinical applications.

Positive selection of V beta 2+ CD8+ T cells

T cells bearing V beta 4, V beta 6, V beta 10, V beta 14, and V beta 17a are positively selected by MHC class I and/or class II molecules with poorly elucidated mechanisms. In this paper levels of V beta 2+ CD4+ and V beta 2+ CD8+ T cells from 33 inbred, five F1 hybrid, and 48 [(C58 x DBA/2)F1 x DBA/2] backcross mice have been examined. The results show that (i) V beta 2+ CD8+ T cells are positively selected by MHC class I H-2k molecules, (ii) this positive selection might be mediated by a non-H-2 ligand(s) in association with the Kk molecule, and (iii) inbred strains of mice, so far examined, do not have endogenous superantigens for deletion of V beta 2+ T cells.

Novel cell junctions induced by activating Thy-1-specific antibodies

KT16, like other anti-Thy-1 antibodies, induces T cell aggregation. Protein A-gold labelling shows the antibody to be concentrated along areas of intercellular contacts. Electron micrographs of KT16 treated T cells reveal a consistent type of junction between the cells. We demonstrate that this type of cell junction is Thy-1 specific, is predominantly the property of antibodies directed against a particular epitope, and is distinct from cellular aggregation caused by concanavalin A or anti-CD3 antibodies. The degree of adhesiveness induced by different anti-Thy-1 antibodies is related to their mitogenic capacity.

Tcrb-V3+ T-cell deletion and a mouse mammary tumor provirus, Mtv-27

Genes encoding superantigens which delete Tcrb-V3+ T cells co-segregate with mouse mammary tumor proviruses (Mtv), Mtv-1, Mtv-3, Mtv-6, Mtv-13, and Mtv-44. We have examined percentages of Tcrb-V3+ T cells and Mtv integrations in [(B10 x NZB)F1 x B10.BR] mice, and show that Mtv-27 as well as Mtv-3 from NZB mice co-segregate with genes encoding deletion ligands for Tcrb-V3+ T cells without recombination.

Positive and negative selection of Tcrb-V6+ T cells

Tcrb-V6+ T cells are deleted by an endogenous superantigen probably encoded by a mouse mammary tumor provirus (Mtv), Mtv-7, in association with major histocompatibility complex (MHC) class II molecules. In contrast, Tcrb-V6+CD4+ T cells are positively selected by MHC class II E molecules in Mtv-7- mice. We have examined the levels of Tcrb-V6+CD4+ and Tcrb-V6+CD8+ T cells from six combinations of backcross mice. In this paper we show that: 1) Tcrb-V6+CD8+ T cells can be positively selected by MHC class I molecules; 2) MHC class II A molecules can also influence the levels of Tcrb-V6+CD4+ T cells; 3) Mtv-7- NZW mice have a new Mtv, Mtv-44, which cosegregates with a gene encoding the partial deletion ligand for Tcrb-V6+ T cells; 4) the remaining Tcrb-V6+ T cells from mice with partial deletion of these T cells appear not to be anergized in the periphery.

Influence of T cell receptor V alpha expression on Mlsa superantigen-specific T cell responses

Recognition of conventional foreign antigen by T cells is determined by the expression of multiple variable regions of both alpha and beta chains of the T cell receptor (TCR) alpha/beta heterodimer. In contrast, there exists a class of antigens that appears to interact with the TCR alpha/beta heterodimer through the variable region on the beta chain (V beta), independent of other TCR components, a property that has led to their designation as superantigens. The goal of the present study was to analyze V alpha use in V beta 6+ T cells responsive to the superantigen, Mlaa. Results indicate that while deletion of T cells expressing V beta 6 in Mlsa-expressing mice is essentially complete and therefore appears to occur regardless of V alpha usage, in vitro Mlsa stimulation of T cells from Mlsa-negative mice results in significant skewing of V alpha use among responding V beta 6+ T cells. This indicates that V alpha expression influences recognition of the superantigen, Mlsa by mature peripheral T cells.

Negative selection of Tcra-V8+CD8+ T cells by MHC class I molecules

Tcrb-V-specific positive and negative selection of T cells has been well documented. In contrast, nothing is known about Tcra-V-specific selection. Using Tcra-V8-specific KT50 antibody Tcra-V8-specific selection of T cells has been examined. The CD8+ T cell subpopulation bearing Tcra-V8 are shown to be negatively selected by major histocompatibility complex (MHC) class I H-2Kd and H-2Dd/Ld molecules. Furthermore, percentages of these T cells are also influenced by Tcra-V haplotypes. Involvement of non-H-2 self (super)antigens in this MHC class I restricted negative selection, however, remains to be determined.

Tcrb-V3+ T-cell deletion and a new mouse mammary tumor provirus, Mtv-44

Genes encoding endogenous superantigens causing Tcrb-V3+ T-cell deletion co-segregate with mouse mammary tumor proviruses (Mtv), Mtv-3, Mtv-6, and Mtv-13. In addition Mtv-1 has been implicated in deletion of these T cells. We have examined levels of Tcrb-V3+ T cells and Mtv integrations in the following offspring and their parental strains, [(CBA-T6 x NZW)F1 x CBA], [(CBA x C3H/He)F1 x CBA], and [(B10.S (9R) x NOD]F1 mice. We show that a new Mtv (Mtv-44) from NZW mice and Mtv-1 from C3H/He mice cosegregate with genes encoding ligands for partial deletion of Tcrb-V3+ T cells and that some NOD mice have an additional Mtv (Mtv-45) which is closely linked to Mtv-3.

Positive selection of Tcrb-V10b+ T cells

The Tcrb-V10b+ T cell population has been examined with a newly established antibody, KT10b, specific for Tcrb-V10b but not Tcrb-V10a. H-2E+ mice have higher levels of Tcrb-V10b+ T cells (4.3%-11.0%) than H-2E- mice (2.2%-4.9%). This difference appears to be determined by levels of Tcrb-V10b+ T cells in the CD4 population. F1 hybrid mice between H-2E+ and H-2E- mice dominantly express higher levels of Tcrb-V10b+ T cells. [NOD (E-) x (NOD x A (E+))F1] backcross mice show positive selection of Tcrb-V10b+CD4+ T cells by H-2E. On the other hand other backcross analyses reveal positive selection of Tcrb- V10B+CD8+ T cells by certain major histocompatibility class I molecules. Involvement of non-H-2 antigens in these positive selections remains to be determined.

Endogenous ligands selecting T cells expressing particular V beta elements

It has recently become clear that the minor lymphocyte stimulatory antigens (Mls) and other endogenous ligands which lead to the partial or total deletion of T cells bearing particular V beta segments are encoded by mouse mammary tumor virus (MMTV). We review here the genetic analyses of multiple V beta 11 and V beta 3 deletion ligands and demonstrate the involvement of MMTV in all examples. Several features of Mls and the V beta 11/V beta 3 deleting ligands identify them as members of the superantigen family. Bacterial superantigens are known to bind both MHC class II and the TCR in regions distinct from conventional peptide antigens. Within the MMTV genome, the 3' LTR has been identified as encoding superantigen function. We present data demonstrating that in vitro translation identifies the major product of the open reading frame (ORF) within the 3' LTR as a type II integral membrane glycoprotein. It is proposed that the type II membrane glycoprotein interacts with MHC and TCR in a manner analogous to the bacterial superantigens and distinct from conventional peptide antigen. Several unanswered questions regarding superantigen action remain; what determines total or partial deletion? How is Mls transferred between cells? These questions are addressed in the discussion.

Affinity enhancement and transmembrane signaling are associated with distinct epitopes on the CD8 alpha beta heterodimer

CD8 is a heterodimeric membrane glycoprotein on MHC class I-restricted T lymphocytes that cooperates with the alpha beta CD3 TCR in the recognition of MHC class I molecules presenting antigenic peptides. Co-operation has two components: enhancement of the affinity of MHC/peptide-TCR interaction, and signal transduction through the T cell membrane. The cytolytic function of CTL is primarily dependent on the affinity-enhancement component of CD8-TCR cooperation whereas activation of resting CD8+ T cells is primarily dependent on transmembrane signaling. Using a panel of mAb, two to the alpha-chain and three to the beta-chain of CD8, we investigated the relationships between epitopes and functional regions of the CD8 molecule. Two of the antibodies, one to the alpha-chain and one to the beta-chain of CD8, inhibit the cytolytic function of CTL but not the generation of CTL from resting T cells. Another two antibodies, also one to the alpha- and one to the beta-chain, inhibited the generation of CTL while enhancing the cytolytic function of CTL. These results suggest that both the alpha- and beta-chain of CD8 possess two distinct regions, one involved in affinity enhancement and the other in transmembrane signaling. The former may be the MHC class I-binding region whereas the latter may associate with the alpha beta CD3 TCR. The data can explain the apparent functional equivalence of CD8 alpha alpha homodimers and alpha beta heterodimers.

Affinity enhancement and transmembrane signaling are associated with distinct epitopes on the CD8 alpha beta heterodimer

CD8 is a heterodimeric membrane glycoprotein on MHC class I-restricted T lymphocytes that cooperates with the alpha beta CD3 TCR in the recognition of MHC class I molecules presenting antigenic peptides. Co-operation has two components: enhancement of the affinity of MHC/peptide-TCR interaction, and signal transduction through the T cell membrane. The cytolytic function of CTL is primarily dependent on the affinity-enhancement component of CD8-TCR cooperation whereas activation of resting CD8+ T cells is primarily dependent on transmembrane signaling. Using a panel of mAb, two to the alpha-chain and three to the beta-chain of CD8, we investigated the relationships between epitopes and functional regions of the CD8 molecule. Two of the antibodies, one to the alpha-chain and one to the beta-chain of CD8, inhibit the cytolytic function of CTL but not the generation of CTL from resting T cells. Another two antibodies, also one to the alpha- and one to the beta-chain, inhibited the generation of CTL while enhancing the cytolytic function of CTL. These results suggest that both the alpha- and beta-chain of CD8 possess two distinct regions, one involved in affinity enhancement and the other in transmembrane signaling. The former may be the MHC class I-binding region whereas the latter may associate with the alpha beta CD3 TCR. The data can explain the apparent functional equivalence of CD8 alpha alpha homodimers and alpha beta heterodimers.

Co-segregation of a gene encoding a deletion ligand for Tcrb-V3+ T cells with Mtv-3

A gene encoding the endogenous superantigen Mlsc, which deletes Tcrb-V3+ T cells in the NOD inbred mouse strain, was found to co-segregate with Mtv-3 on chromosome 11. This identifies a fourth gene encoding a deletion ligand for Tcrb-V3+ T cells and extends recently published observations in support of the hypothesis that a number of endogenous superantigens are the products of Mtv proviruses.

The genetic basis of negative selection of Tcrb-V11+ T cells

Non-H-2 genes responsible for negative selection of Tcrb-V11+ T cells were examined using backcross mice of various strains with C58, which does not delete Tcrb-V11+ T cells. Two independently segregating genes were found: one leading to partial deletion was closely linked to Ly-2/Ly-3 on chromosome 6, and the second giving virtually complete deletion has not yet been mapped. The A strain had only the former, whereas BALB/c, BALB.K, B10.BR, CBA-T6, C3H/He, and DBA/2 expressed both of these genes. Although a gene(s) of the NIH strain led only to partial deletion, the chromosomal localization of the gene(s) has not yet been determined: no informative polymorphic molecules are expressed from genes on chromosome 6 of this strain.

Genes encoding ligands for deletion of V beta 11 T cells cosegregate with mammary tumour virus genomes

The T-cell receptor (TCR) repertoire is selected in the thymus after rearrangement of genes encoding TCR alpha and beta chains. Selection is based on the recognition by newly emergent T cells of self-ligands associated with molecules of the major histocompatibility complex: some combinations result in positive selection, others in negative selection. Negative selection, or clonal deletion, is an important mechanism for eliminating autoreactive T cells. A group of self-ligands involved in clonal deletion was identified because they, like exogenous superantigens, were recognized by almost all T cells expressing particular TCR V beta genes. V beta 17a T cells are deleted by a tissue-specific ligand; V beta 6, V beta 7, V beta 8.1 and V beta 9 T cells are deleted by the minor lymphocyte-stimulating (Mls) determinant Mls-1a; V beta 3 T cells by Mls-2a and Mls-3a; V beta 11 T cells by ligands encoded by independently segregating genes; and V beta 5 T cells by ligands encoded by two genes. Chromosome mapping using recombinant inbred strains of mice and classic backcrosses show that Mls-1a in DBA/2 mice is encoded on chromosome 1, that one of the two ligand genes for deletion of V beta 5 T cells maps to chromosome 12 and that a ligand gene for V beta 11 deletion is linked to the CD8 locus on chromosome 6. Here we present evidence from three sets of backcross mice for concordance between V beta 11 deletion ligand genes on chromosomes 6, 12 and 14 and endogenous mouse mammary tumour virus integrant (Mtv) genomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between the V beta 4+ CD8+ T-cell population and the H-2d haplotype

The V beta 4+ T-cell population was examined with a newly established antibody, KT4, specific for V beta 4. Between 4.8% and 19.4% of CD3+ peripheral T cells from various inbred strains of mice or F1 hybrids expressed V beta 4. The CD4 T-cell population had higher numbers of V beta 4+ T cells (5.5%-20.6%) than the CD8 T-cell population (2.5%-10.7%). Deletion of certain V beta-expressing T cells due to the presence of the Mlsa antigen and/or the absence of certain Tcrb-V genes increased relative numbers of V beta 4+ T cells. The data suggest that V beta 4+ CD8+ T cells might be positively selected by H-2d molecules.

Epitope-specific binding of CD8 regulates activation of T cells and induction of cytotoxicity

Functions of the CD8 molecule were examined to determine whether CD8 is merely a ligand-binding molecule and/or is involved in signal transduction. Using KT112 (anti-CD8 beta), CD8 was demonstrated to transduce an activation signal leading to cytotoxicity. Conformational changes of the CD8 molecule might be responsible for the activation, because (i) KT15 (anti-monomorphic CD8 alpha), but not antibodies specific for polymorphic CD8 alpha determinants, abrogated KT112 (anti-CD8 beta)-induced cytotoxicity without blocking the binding of KT112, whilst (ii) KT112 (anti-CD8 beta) inhibited KT15 (anti-monomorphic CD8 alpha)-mediated augmentation of proliferation triggered by a V beta 11-specific antibody without blocking the binding of KT15.

Two monoclonal antibodies specific for the T cell receptor V alpha 8

Two monoclonal antibodies, KT50 and KT65, specific for V alpha 8 have been established. This was determined as follows: (a) 4 T cell clones, C6, R1, G22 and I9, out of 43 T cell clones with various antigen specificities, major histocompatibility complex restrictions and V beta usages not only bound KT50 and KT65 but also expressed V alpha 8 mRNA, (b) KT50 and KT65 precipitated molecules from the clone C6 similar to the T cell receptor molecules precipitated in C6 cells by KT11 (anti-V beta 11) or KTL2 (anti-Ti) and (c) KT50 and KT65 were mitogenic and induced cytotoxicity. All strains of mice so far examined have populations of KT50+ and KT65+ T cells of 1.4%-3.6% and 0.9%-2.6%, respectively. Different H-2 haplotypes were not observed to affect the number of cells expressing KT50 or KT65. In addition KT15 (anti-CD8), without cross-linking to KT50 or KT65, augmented proliferation triggered by KT50 or KT65.

Minor transplantation antigens: their role in shaping the T cell repertoire

Minor transplantation, or histocompatibility (H), antigens are the targets of host-versus-graft (hvg) and graft-versus-host (gvh) reactions that occur when organs or tissues are exchanged between members of the same species who, although genetically not identical, are matched for their major histocompatibility complex (MHC) encoded transplantation antigens. Genes encoding minor H antigens map outside the MHC, on a number of different chromosomes. Whilst gvh and hvg reactions against individual minor H antigens are relatively weak, certainly in comparison with such reactions against MHC antigens, the presence of multiple minor H differences (the situation encountered in man) gives rise to very vigorous reactions that can endanger the survival of graft or host, or both. This is the pathological role of minor H antigens and, indeed, it was this role which was first designated to the MHC antigens, before their physiological role as guidance molecules for T lymphocytes was discovered. Recently, a potential physiological role for minor H antigens has been uncovered by the finding that the presence of certain minor H alleles in mice leads to removal in the thymus (negative selection) of all those T cells expressing a particular T cell receptor (TCR) gene. Such cells therefore never reach the periphery, where they might otherwise give rise to autoimmune reactions. The T cell repertoire is thus moulded by at least some minor H antigens, which may therefore be regarded as non-MHC immune response genes. Furthermore, T cell receptor usage by T cells specific for allogeneic minor H antigens appears not to be representative of T cell receptor usage in the peripheral pool.(ABSTRACT TRUNCATED AT 250 WORDS)

T-cell receptor-specific monoclonal antibodies against a V beta 11-positive mouse T-cell clone

Two monoclonal antibodies specific for the mouse T-cell receptor (Tcr) have been established by immunization with a V beta 11+ T-cell clone, clone C6. One is a rat antibody, KT11 (IgG2b, k), specific for the V beta chain of C6, V beta 11. This was demonstrated by the fact that the strain distribution pattern of KT11+ cells was similar to that of V beta 5, 8, 9, 11, 12, and 13 and that the gene that encodes the molecule detected by KT11 was closely linked to V beta 8 in (B10 X SJL)F1 X SJL backcross mice. Furthermore, V beta of C6 has been cloned from a lambda gt10 cDNA library and was demonstrated to be identical to the V beta 11 published sequences. All strains of mice that do not express major histocompatibility complex class II E molecules had higher numbers of KT11+ cells than E+ strains. The KT11+ population in A strain mice and its H-2 congenic strains, however, was not affected by the presence or absence of E molecules. The other is a mouse antibody, KTL2 (IgM), specific for the idiotope of the Tcr expressed on the clone C6. Both antibodies were mitogenic and induced cytotoxicity. Expression of epitopes detected by KT11 or KTL2 was down-modulated by a T3 epsilon-specific antibody 145-2C11.

Down-regulation of the T cell receptor by a mitogenic anti-Thy-1 antibody

Antigen-specific unresponsiveness lasting at least 2 weeks can be induced in a T cell clone by 24-h pretreatment with mitogenic anti-T cell receptor antibodies. In this report the relationship is explored between the antigen-specific unresponsiveness and activation pathways triggered via the T cell receptor and Thy-1: the latter pathway is dependent on the former. A mitogenic anti-Thy-1 antibody (KT16) made the T cell clone unresponsive to specific antigen and to an anti-T cell receptor antibody coupled to Sepharose. The unresponsiveness lasted for at least 7 days. However, cells made unresponsive to specific antigen in these ways (the T cell receptor and Thy-1) could be activated by both interleukin 2 and KT16. KT16 down-modulated the T cell receptor immediately after the pretreatment, but not on day 7 after the pretreatment. These facts indicate that the state of the unresponsiveness was caused by blocking transduction of an activation signal triggered by the T cell receptor to an activation pathway shared by the T cell receptor and Thy-1.