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Results for “Double-negative”

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At least 19 recordsLinked to original sources

PubMed1992

T cell receptor V beta repertoire of double-negative alpha/beta T cells in patients with systemic sclerosis.

OBJECTIVE: To analyze the T cell receptor V beta gene on double-negative (DN) alpha/beta T cells, which are increased in number, on peripheral blood lymphocytes (PBL) from patients with systemic sclerosis (SSc). METHODS: The DN alpha/beta T cells were sorted by flow cytometry from PBL obtained from 3 patients with SSc. The V beta repertoire was analyzed by polymerase chain reaction. RESULTS: Only 1 or 2 V beta genes (V beta 5/7, 5, or 17) were predominantly expressed on DN alpha/beta T cells from these 3 patients. CONCLUSION: The V beta repertoire on DN alpha/beta T cells in PBL from patients with SSc is rather restricted.

Base Sequence↗

PubMed2025

A double-negative prostate cancer subtype is vulnerable to SWI/SNF-targeting degrader molecules.

Proteolysis targeting chimera (PROTAC) therapies degrading SWI/SNF ATPases offer a novel approach to interfere with androgen receptor (AR) signaling in AR-dependent castration-resistant prostate cancer (CRPC-AR). To explore the utility of SWI/SNF therapy beyond AR-sensitive CRPC, we investigated SWI/SNF-targeting agents in AR-negative CRPC. SWI/SNF targeting PROTAC treatment of cell lines and organoid models reduced the viability of not only CRPC-AR but also WNT-signaling dependent AR-negative CRPC (CRPC-WNT). The CRPC-WNT subgroup represents 11% of around 400,000 cases of CRPC worldwide who die yearly of CRPC. We discovered that SWI/SNF ATPase SMARCA4 depletion interfered with the master transcriptional regulator TCF7L2 (TCF4) in CRPC-WNT. Functionally, TCF7L2 maintains proliferation via the MAPK signaling axis in this subtype of CRPC. These data suggest a mechanistic rationale for interventions that perturb the DNA binding of the pro-proliferative TCF7L2 transcription factor (TF) and/or direct MAPK signaling inhibition in the CRPC-WNT subclass of advanced prostate cancer.

Journal Article↗

PubMed1992

Quantitative analyses comparing all major spleen cell phenotypes in BB and normal rats: autoimmune imbalance and double negative T cells associated with resistant, prone and diabetic animals.

The BB rat is a model of spontaneous autoimmune diabetes. To characterize quantitatively all known immune cell subsets involved in disease pathogenesis, FACS analysis of spleen cells was performed in diabetes-prone (DP) and acutely diabetic (D) BB rats and compared with diabetes-resistant (DR) BB and normal Wistar-Furth (WF) strains. We observed increased percentages of splenic NK cells in DP and D animals compared with DR rats using an NK-specific monoclonal antibody. We found increased proportions of splenic macrophages in the T-lymphopenic DP and D rats and low macrophage contents in DR spleens compared with WF spleens. We observed that percentages of the CD4-CD8- T cell receptor alpha/beta+ (double-negative) T cell subset were strikingly increased in the lymphopenic DP and D animals, compared with DR animals. We observed increased percentages of activated splenic CD5+ T cells expressing the IL-2 receptor and MHC class II antigen in DP and D rats compared with DR animals. Our studies suggest that (a) splenic NK cells and macrophages quantitatively appear to be involved in the pathogenesis of diabetes; (b) double-negative T cells escape from the T cell depletion process; (c) a marked increase of activated splenic T cells suggests diabetes is associated with general T cell activation processes; and (d) an altered balance among the different immune cell subsets may in part explain the pathogenesis of diabetes, since marked relative changes are observed when comparing the DR strain to the DP strain in both the prediabetic and diabetic stages.

Animals↗

PubMed1992

Induction and suppression of delayed-type hypersensitivity to non-MHC antigens during lethal graft-versus-host reaction.

A delayed-type hypersensitivity reaction (DTH) to non-MHC Ag was detected during a lethal graft-vs-host reaction (GVH) induced by incompatibility for non-MHC Ag alone. In this model, when appropriate doses of B10.D2 bone marrow and lymphoid cells are grafted to irradiated (DBA/2 x B10.D2)F1 recipients, the ensuing GVH, directed against those DBA/2 non-MHC Ag absent from the B10.D2 background, results in virtually 100% mortality in less than 3 mo; donor alloimmunization against the host histocompatibility Ag considerably reduces mortality, and survival rates of 80 to 100% are common. The experiments reported here show that: 1) the cell responsible for DTH induction expresses the CD4+ CD8- phenotype; 2) CD4+ cells likewise seem to play a predominant role in the pathology of lethal GVH in this genetic combination; 3) the alloimmunization protocol that abrogates mortality also abolishes GVH-associated DTH; and 4) this suppressive effect, as shown elsewhere for the protection against mortality, is mediated by CD4- CD8- "double negative" Thy-1+ CD3+ T suppressor cells. Thus, there is a good parallel between lethal GVH and its associated DTH as concerns both induction and suppression of the two phenomena, suggesting that mortality and DTH may represent different manifestations of a common underlying mechanism. Initiation of the effector phase of DTH in the adoptive transfer model seems to be dependent on the presence of a Thy-1+ double-negative cell in the transfer inoculum; the possible relationship of this double-negative cell to the Th-1-type CD4+ DTH-mediating cell recently shown to induce lethal GVH is discussed.

Animals↗

PubMed1992

CD45 isoform expression during T cell development in the thymus.

Various isoforms of leukocyte common antigen, or CD45, are expressed differentially on T cells at different stages of development and activation. We report studies on CD45 isoform expression on various subsets of human T cells using two- and three-color flow cytometry and cell depletion. Bone marrow cells that were depleted of CD3+ and HLA-DR+ cells were CD45RA-RO-. The earliest CD3-CD4-CD8-CD19- thymocytes were CD45RO- with 20%-30% CD45RA+ cells. The most prominent population of CD4+CD8+ double-positive thymocytes were CD45RA-RO+. Even the CD4+CD8+ blasts were greater than 90% CD45RO+. About 80% of single-positive thymocytes (CD4+CD8- or CD4-CD8+) were also CD45RO+. Only 4.3% of CD4+ and 18% of CD8+ single-positive thymocytes were CD45RA+. In contrast, cord blood T cells which represent the stage that immediately follows single-positive thymocytes, contained 90% CD45RA+ cells. Thus, in terms of CD45 isoform expression, single-positive thymocytes are more like double-positive cells than cord blood T cells. These results suggest the following sequence of CD45 isoform switching during T cell development: CD45RA-RO- or RA+RO- (double-negative thymocytes)----RA-RO+ (double-positive and most single-positive thymocytes)----RA+RO- (cord blood T cells), the last switch from CD45RO to CD45RA occurring as a final step of maturation in the thymus.

Antigens, CD↗

PubMed1992

Relative resistance of intermediate TCR cells to anti-CD3 mAb in mice in vivo and their partial functional characterization.

In addition to T cells differentiated in the thymus, T cells, possibly of extrathymic origin, were recently demonstrated in the liver of mice. These T cells are characterized by the expression of intermediate TCR and contain double-negative CD4-8- cells. A further characterization of intermediate TCR cells was carried out. When mice were injected ip with anti-CD3 mAb, bright TCR cells (i.e., regular T cells) and intermediate TCR cells were reduced on Day 3, depending on the amount of mAb. Because of the resistance of intermediate TCR cells to treatment, injection of an appropriate dose of antibody (i.e., 100 micrograms/mouse) eliminated most bright TCR cells, but not intermediate TCR cells. This dose revealed that a significant proportion of intermediate TCR cells also reside in the periphery. Hepatic and splenic mononuclear cells (MNC), in which intermediate TCR cells became abundant after treatment, showed a unique response to T cell mitogens and IL-2. Thus, the intermediate TCR cell-enriched population could not respond to a T cell mitogen, Con A, but responded well to a super antigen, staphylococcal enterotoxin B, and IL-2. MNC obtained from athymic nude mice, which comprise only intermediate TCR cells, responded in the same manner. These findings revealed that intermediate TCR cells are present not only in the liver but also in the periphery, and that they have a unique function distinct from regular T cells.

Animals↗

PubMed2026

A distinct effector B cell population drives autoantibody production in SARS-CoV-2 infection.

Autoantibodies (autoAbs) are linked to mortality and Long COVID, yet their cellular origins remain unclear. We analyzed the INCOV cohort and identified 12 age- and sex-matched participants with varying autoAb abundance and integrated single-cell RNA-seq and ATAC-seq data from B cells, plasma proteomics, proteome-wide autoAb profiling, clinical data, and in vitro assays. AutoAb abundance inversely correlated with neutralizing IgG and declined as infection resolved, paralleling the contraction of atypical memory B cells (AtMs). In vitro, AtMs preferentially differentiated into autoAb-producing antibody-secreting cells upon TLR7/8 stimulation. CD11c+ AtMs (double-negative 2, DN2s) in autoAb-high individuals exhibited increased TLR7 signaling, oxidative stress, and isotype switching, regulated by transcription factors T-bet and XBP1. Integrated genetic and genomic analyses showed that DN2s had the strongest enrichment for autoimmune trait heritability and inferred regulatory effects of autoimmune risk variants among B cell subsets. These findings identify DN2s as key precursors of autoAb-producing cells during SARS-CoV-2 infection.

B cell↗

PubMed2026

TFAP2B and FOXC1 are associated with biologically and clinically distinct differentiation states in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) comprises biologically distinct subtypes, including luminal androgen receptor (LAR) tumors, but routine immunohistochemical markers incompletely capture lineage-associated differentiation states. We investigated TFAP2B, an AP-2 family transcription factor linked to epithelial differentiation, and FOXC1, a basal-like-associated transcription factor, as complementary markers of luminal and basal differentiation in TNBC. In a tissue microarray of 105 TNBCs, tumors were stratified as TFAP2B-dominant, FOXC1-dominant, or double-negative according to relative marker predominance and characterized using lineage, proliferation, molecular, immune, and chemotherapy-response parameters. TFAP2B-dominant tumors were associated with a coherent luminal phenotype, including apocrine/lobular enrichment, strong MUCL1 and AR expression, high CK18, low SOX10, reduced proliferation, frequent wild-type p53 patterns and retained RB1 expression, and low PD-L1 expression. FOXC1-dominant tumors showed contrasting basal-like features. These associations were independently supported at the transcriptional and genomic levels in the METABRIC TNBC cohort. FOXC1-dominant tumors also showed more frequent chemotherapy-induced downstaging than TFAP2B-dominant tumors. Together, we identify TFAP2B as a marker associated with luminal differentiation in TNBC and support combined TFAP2B/FOXC1 assessment as a practical framework for identifying clinically relevant TNBC differentiation states.

Humans↗

PubMed1992

Immunoregulatory functions for murine intraepithelial lymphocytes: gamma/delta T cell receptor-positive (TCR+) T cells abrogate oral tolerance, while alpha/beta TCR+ T cells provide B cell help.

Past work has shown that a subset of effector T cells with unique characteristics could abrogate hapten- or antigen-induced tolerance, and the reconstitution of this immune response has been termed contrasuppression. We have studied contrasuppression in a model of oral tolerance (OT) in which adoptively transferred antigen-specific T contrasuppressor (Tcs) cells reverse OT and result in antibody responses to the eliciting antigen. In the present study, we show that murine intraepithelial lymphocytes (IELs) from mice orally immunized with sheep red blood cells (SRBC) contain T cells that exhibit Tcs cell activity. This effect was mediated by CD3+ gamma/delta T cell receptor-positive (TCR+), but not alpha/beta TCR+ T cells, and gamma/delta TCR+ Tcs cells were associated with both the CD4-,CD8+ and CD4-,CD8- (double-negative) IEL fractions. The CD4-,CD8+ gamma/delta TCR+ IELs were further separated into Vicia villosa-adherent and -nonadherent fractions. Adoptive transfer of V. villosa-adherent gamma/delta TCR+ T cells to mice with OT to SRBC resulted in splenic IgA, IgM, and IgG subclass anti-SRBC responses, while V. villosa-nonadherent gamma/delta TCR+ T cells were without activity. The gamma/delta TCR+ IELs did not support in vitro antibody responses in B cell cultures, while alpha/beta TCR+ IELs were effective T helper cells. Further, cytokine production by the gamma/delta TCR+ IELs was examined, and the gamma/delta TCR+ V. villosa-adherent fraction, which possessed contrasuppressor function, contained low levels of IL-5 mRNA and small numbers of IL-5-producing cells when compared with alpha/beta TCR+ IELs and V. villosa-nonadherent gamma/delta TCR+ IELs. Our results now show that mouse IELs contain two distinct types of T cells that function in the immune response, e.g., alpha/beta TCR+ T cells that produce IL-5 and function as helper cells, and gamma/delta TCR+ T cells that restore antibody responses in mice that had been orally tolerized with antigen.

Animals↗

PubMed1992

In vivo and in vitro clonal deletion of double-positive thymocytes.

To study the processes of thymic development, we have established transgenic mice expressing and alpha/beta T cell antigen receptor (TCR) specific for cytochrome c associated with class II major histocompatibility complex (MHC) molecules. The transgenic TCR chains are expressed by most of the thymocytes in these mice, and these cells have been shown to efficiently mature in association with Ek- and Ab-encoded class II MHC molecules. This report describes a characterization of the negative selection of these transgenic thymocytes in vivo that is associated with the expression of As molecules. Negative selection by As molecules appears to result in the deletion of a late stage of CD4/CD8 double-positive thymocytes in that there is a virtual absence of transgenic TCR bearing CD4 single-positive thymocytes. This phenotype is accompanied by the appearance of CD4/CD8 double-negative thymocytes and peripheral T cells that are functionally antigen reactive. The process of negative selection has also been investigated using an in vitro culture system. Upon presentation of cytochrome c by Eb-expressing nonthymic antigen-presenting cells, there occurs an antigen dose-dependent deletion of the majority of CD4/CD8 double-positive thymocytes. In contrast, presentation of Staphylococcal enterotoxin A by Eb in vitro results in minimal deletion of double-positive thymocytes. In addition, we use this in vitro model to examine the effects of cyclosporin A on negative selection. In contrast to its effects on mature T cells, and the findings of others in vivo, cyclosporin A does not inhibit antigen-induced deletion of double-positive thymocytes. Finally, a comparison of the antigen dose responses for thymocyte deletion and for peripheral T cell activation indicates that double-positive thymocyte recognition is more sensitive than mature T cells to antigen recognition.

Animals↗

PubMed1992

Distinctive selection mechanisms govern the T cell receptor repertoire of peripheral CD4-CD8- alpha/beta T cells.

The T cell receptor (TCR) repertoire of CD4+ and CD8+ alpha/beta T cells is heavily influenced by positive and negative selection events that occur during T cell development in the thymus. The coreceptors CD4 and CD8 appear to be essential for this selection to occur. To gain insight into whether T cells that express TCR alpha/beta but lack either coreceptor (CD4- CD8- TCR alpha/beta or alpha/beta double-negative [DN] cells) are also subject to positive and negative selection, and whether selection can occur in the absence of coreceptors, we have performed an extensive immunogenetic analysis of the TCR V beta repertoire of alpha/beta DN cells in lymph nodes of normal mice. Our results show that alpha/beta DN cells appear to be unaffected by clonal deletion of V beta 5 and V beta 11 in I-E-expressing mice, and do not undergo deletion of V beta 6- and V beta 8.1-expressing T cells in Mls-1a-positive mice. They are also unaffected by positive selection of V beta 17a+ T cells in the context of I-Aq. The results suggest that most selection events require the participation of CD4 and CD8, while alpha/beta DN cells are unselected. This argues that most alpha/beta DN cells probably have never expressed CD4 or CD8. However, a unique form of repertoire selection occurs: enrichment of V beta 17a+ alpha/beta DN cells in I-E+ mice. This could be an instance of coreceptor-independent selection.

Animals↗

PubMed1992

Monoclonal antibodies specific for canine CD4 and CD8 define functional T-lymphocyte subsets and high-density expression of CD4 by canine neutrophils.

The characteristics of canine homologues of CD4 and CD8, defined by murine monoclonal antibodies CA13.1E4 (IgG1) and CA9.JD3 (IgG2a) respectively, are described. These antibodies identify mutually exclusive subpopulations of non-B lymphocytes in peripheral lymphoid organs and blood. However, in thymus the antibodies defined populations of double-positive, double-negative and single-positive cells that showed a progressive maturation consistent with that described for CD4 and CD8 in other mammalian species. Furthermore, functional studies clearly associated cytotoxic effector cell function with the subpopulation reactive with CA9.JD3 (CD8). In contrast, proliferation stimulated by allogeneic cells and mitogens was more pronounced in the subpopulation reactive with CA13.1E4 (CD4). Cell and tissue distribution studies revealed that CA13.1E4 stained neutrophils with equivalent intensity to the staining of peripheral T cells. CA13.1E4 precipitated a 60 kD protein from the surface of T cells and highly purified neutrophils under both reducing and nonreducing conditions. CA9.JD3 precipitated a heterodimer of 32 kd and 36 kD under reducing conditions, and a 70 kD protein under non-reducing conditions. The expression of CD4 by canine neutrophils is without precedent in other mammalian species; the functional significance of neutrophil CD4 expression is puzzling in light of the current understanding of the functions of CD4 which include it's role as a receptor for nonpolymorphic regions of MHC class II molecules.

Animals↗

PubMed1992

Phenotypes of murine leukemia virus-induced tumors: influence of 3' viral coding sequences.

Murine leukemia viruses (MuLVs) induce leukemias and lymphomas in mice. We have used fluorescence-activated cell sorter analysis to determine the hematopoietic phenotypes of tumor cells induced by a number of MuLVs. Tumor cells induced by ecotropic Moloney, amphotropic 4070A, and 10A1 MuLVs and by two chimeric MuLVs, Mo(4070A) and Mo(10A1), were examined with antibodies to 13 lineage-specific cell surface markers found on myeloid cell, T-cell, and B-cell lineages. The chimeric Mo(4070A) and Mo(10A1) MuLVs, consisting of Moloney MuLV with the carboxy half of the Pol region and nearly all of the Env region of 4070A and 10A1, respectively, were constructed to examine the possible influence of these sequences on Moloney MuLV-induced tumor cell phenotypes. In some instances, these phenotypic analyses were supplemented by Southern blot analysis for lymphoid cell-specific genomic DNA rearrangements at the immunoglobulin heavy-chain, the T-cell receptor gamma, and the T-cell receptor beta loci. The results of our analysis showed that Moloney MuLV, 4070A, Mo(4070A), and Mo(10A1) induced mostly T-cell tumors. Moloney MuLV and Mo(4070A) induced a wide variety of T-cell phenotypes, ranging from immature to mature phenotypes, while 4070A induced mostly prothymocyte and double-negative (CD4- CD8-) T-cell tumors. The tumor phenotypes obtained with 10A1 and Mo(10A1) were each less variable than those obtained with the other MuLVs tested. 10A1 uniformly induced a tumor consisting of lineage marker-negative cells that lack lymphoid cell-specific DNA rearrangements and histologically appear to be early undifferentiated erythroid cell-like precursors. The Mo(10A1) chimera consistently induced an intermediate T-cell tumor. The chimeric constructions demonstrated that while 4070A 3' pol and env sequences apparently did not influence the observed tumor cell phenotypes, the 10A1 half of pol and env had a strong effect on the phenotypes induced by Mo(10A1) that resulted in a phenotypic consistency not seen with other viruses. This result implicates 10A1 env in an active role in the tumorigenic process.

Animals↗

PubMed1992

Thymic overexpression of Ttg-1 in transgenic mice results in T-cell acute lymphoblastic leukemia/lymphoma.

T-cell translocation gene 1 (Ttg-1), also called rhombotin, is deregulated upon translocation into the alpha/delta T-cell receptor loci in acute lymphoblastic leukemias bearing the t(11;14)(p15;q11). Ttg-1 encodes a nuclear protein, expressed predominantly in neuronal cells, which belongs to a novel family of transcription factors possessing LIM domains. We utilized the lck proximal promoter to overexpress this candidate oncogene in immature thymocytes of transgenic mice. lckPr Ttg-1 mice develop immature, aggressive T-cell leukemia/lymphomas. Tumor incidence is proportional to the level of Ttg-1 expression. Most tumors contain CD4+8+ cells as well as CD4-8+ cells, which have an immature rather than a mature peripheral phenotype. Ttg-1-induced tumorigenesis preferentially affects a minority population of thymocytes representing an immature CD4-8+ intermediate stage between double-negative CD4-8- cells and double-positive CD4+8+ cells. This model indicates that the aberrant expression of putative transcription factors plays a primary role in the genesis of T-cell acute lymphoblastic leukemias.

Animals↗

PubMed1992

V beta gene family usage in spontaneous lymphomas of AKR mice: evidence for defective clonal deletion.

T-cell receptor (TCR) beta-chain usage and expression of the CD3, CD4, and CD8 differentiation antigens were analyzed in 14 spontaneous AKR lymphomas. Lymphoma cells massively infiltrated and/or proliferated in the organs analyzed (thymus, spleen, and mesenteric lymph nodes), giving rise to a loss of organ structure. One lymphoma occurred only in the thymus, and failed to express CD3, CD4, and CD8. All other lymphomas expressed the CD3/TCR complex. With respect to CD4 and CD8 expression, the lymphomas were either double-negative (DN), double-positive (DP), or single-positive (SP). The frequency of DP (CD4+8+) lymphomas was low compared to the frequency of DP thymocytes in a normal AKR thymus. A substantial heterogeneity was seen in the intensity of CD4 and CD8 expression among various lymphomas, which was independent of the level of CD3 expression. Considering TCR V beta gene family usage, 2 out of 14 lymphomas expressed V beta 6. Normally, V beta 6+ thymocytes are deleted from the thymocyte pool at the immature DP stage of T-cell development in AKR mice. These data support the hypothesis that the lymphocytes in the immature DP stage of T-cell development are susceptible to the induction of AKR lymphomagenesis. The presence of V beta 6+ lymphoma cells indicates that the lymphomagenesis is accompanied by a defective clonal deletion of cells expressing a possible autoreactive TCR.

Animals↗

PubMed2026

ATP-Dependent Chromatin Remodelers in Prostate Cancer Progression and Therapeutic Resistance.

ATP-dependent chromatin remodelers (ACRs) have emerged as central determinants of prostate cancer (PCa) progression and therapy resistance. Organized into four mechanistically distinct families (SWI/SNF, ISWI, CHD, and INO80/SWR), ACRs govern nucleosome positioning genome-wide and thereby occupy a central position in the epigenomic regulatory landscape that dictates where and when transcription factors, including the androgen receptor (AR), can engage chromatin. This review discusses ACR dysregulation in PCa through both mutational and non-mutational mechanisms. These are illustrated by discussing how the functional consequences are highly context-dependent, varying with disease stage, prior treatment exposure, and tumor ancestry. Loss of the tumor suppressors RB1, TP53, and PTEN each generates specific ACR dependencies that are potentially therapeutically exploitable, including synthetic lethal relationships between PTEN deficiency and SWI/SNF ATPase activity. Across the spectrum of AR signaling states, from hormone-sensitive disease through therapy-resistant neuroendocrine and double-negative PCa subtypes, ACR complex composition and genomic targeting are continuously reprogrammed to enable and sustain lineage plasticity and endocrine therapy escape. Therapeutic strategies targeting SWI/SNF, ISWI, and INO80/SWR complexes are at varying stages of preclinical and clinical development and are attractive novel avenues to target therapy resistant PCa.

ATP dependent chromatin remodeling↗

PubMed1992

Age-dependent increase of extrathymic T cells in the liver and their appearance in the periphery of older mice.

The liver is a major site of generation of extrathymic T cells with unique properties (e.g., expressing intermediate TCR and containing self-reactive clones). We investigated herein whether the levels of extrathymic alpha beta T cells varied in various organs as a function of age. A systematic examination of the number of mononuclear cells in various organs of BALB/c mice revealed that the number of hepatic MNC increased with age whereas the number of thymocytes decreased. These changes were more striking in mice fed under conventional conditions than under specific pathogen-free condition. The age-dependent changes in the number of mononuclear cells in the spleen and lymph nodes were minimal. Although the total proportion of alpha beta T cells in each organ remained constant, the staining patterns of TCR-alpha beta as shown by immunofluorescence profiles varied. The most prominent change was that intermediate TCR-alpha beta cells, which constituted a small population in the liver of young mice, expanded in the liver of older mice. Intermediate TCR cells appeared even in the periphery of older mice. These findings were confirmed by the appearance of extrathymic T cells with other unique properties, e.g., double-negative CD4-8- phenotype and CD44 expression. In athymic nude mice, only intermediate TCR cells were present in the liver and periphery. An age-dependent increase of intermediate TCR cells was also seen in these mice. Taken together with the result of bromodeoxyuridine-injection experiment, which showed an intensive in vivo proliferation of cells in the hepatic sinusoids, extrathymic T cells may differentiate predominantly in the liver and appeared even to the periphery in older mice.

Age Factors↗

PubMed1976

Serological differential diagnosis of viral hepatitis in adults.

Serum samples from different groups of adults were tested for HBsAg and IHxAg, using a complement-fixation microtest and the Indian-ink immune reaction, respectively. (i) In healthy men 18-24 years of age, living in camps in closed communities, HBsAg was demonstrated in 1.5%, IHxAg in 12.2%, and both antigens in 0.7%. The incidence of HBsAg positivity seems to be age-dependent and influenced by environmental factors. (ii) For patients hospitalized with liver and/or biliary-tract diseases other than hepatitis, the respective percentages were 10, 13.5 and 4.5%. (iii) Of the cases clinically diagnosed as infectious hepatitis (IH, hepatitis A) or serum hepatitis (SH, hepatitis B), 14% were positive for both antigens whereas 10% were double-negative; 76% were positive for either HBsAg or IHxAg. In two-thirds of the single-positive cases the demonstrated antigen agreed with the clinical diagnosis, in one-third the unexpected antigen was present. (iv) SGPT and thymol turbidity values agreed better with the serological findings that with the clinical diagnosis. The number of days in hospital appeared to be related to both the serological findings and the clinical diagnosis. The clinical course was the most severe for those having both antigens in blood. (v) IHxantibodies from early convalescence were sensitive, those from a later stage were resistant, to 2-mercaptoethanol. (vi) No correlation was found between the presence of IHxAg and that of the rheumatoid factor. (vii) The IHx Indian-ink reaction is disturbed by the presence of labile serum proteins while the essentially similar reverse passive haemagglutination reaction was not affected by them. (viii) Testing for IHxAg seems to be a procedure valuable in the differential diagnosis of IH and SH, though the results are less convincing in adult age than in childhood.

Adolescent↗