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Results for “Double-negative”

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PubMed1990

A large fraction of human peripheral blood gamma/delta + T cells is activated by Mycobacterium tuberculosis but not by its 65-kD heat shock protein.

We report that M. tuberculosis organisms, but neither PHA nor allogeneic stimulator cells, preferentially activate gamma/delta+ cells within E rosette-purified peripheral blood T cells. gamma/delta+ T cells from purified protein derivative (PPD)-nonimmune healthy donors were enriched by depletion of CD4+ and CD8+ cells; double-negative (DN) cells contained 65-92% gamma/delta+ T cells. Limiting dilution (LD) analyses revealed that 1 of 2-19 purified DN cells proliferated in response to mycobacteria, while frequencies of DN cells proliferating in response to a recombinant 65-kD heat shock protein (hsp 65) of M. tuberculosis/M. bovis were 10-20-fold lower. Established clones of mycobacteria-reactive gamma/delta+ T cells specifically recognized mycobacteria, but neither PPD nor hsp 65. Restimulation of these clones required the presence of PBMC feeder cells; EBV-transformed lymphoblastoid cell lines could not substitute for PBMC. Mycobacteria-reactive gamma/delta+ clones proliferated equally well in the presence of autologous or allogeneic (HLA-DR-different) PBMC feeder cells and thus were not MHC class II restricted. Taken together, these results demonstrate that mycobacteria-reactive gamma/delta+ T cells are present in high frequency in the peripheral blood of healthy individuals, and suggest that hsp 65 of mycobacteria is not a major antigen for gamma/delta+ T cells of normal PPD-nonimmune blood donors.

HLA-DR Antigens↗

PubMed1991

T cell receptor-mediated selection of functional rat CD8 T cells from defined immature thymocyte precursors in short-term suspension culture.

Recent results have indicated that positive and negative repertoire selection act on the major population of CD4,8 double-positive (DP) thymocytes that express 5-10-fold less T cell receptor (TCR) than mature T cells (i.e., they are TCRlow). Since DP cells obtained ex vivo are heterogeneous with regard to their stage within thymic selection, a homogeneous population of virgin DP cells suitable for selection studies was generated in vitro from their immediate precursors, the CD8 single-positive (SP) immature blast cells. To mimic TCR-mediated selection signals, these virgin DP cells were then cultured for another 2 d in the presence of immobilized anti-TCR monoclonal antibodies with or without interleukin 2 (IL-2). Daily monitoring of recovery and phenotype showed that without TCR stimulation, the cells remained DP and became small, TCRlow cells that were lost with a half-life of 1 d, regardless of the presence of IL-2. TCR stimulation resulted in rapid downregulation of CD4 and CD8, maintenance of a larger cell size, and induction of the CD53 antigen that marks mature and CD4,8 double-negative rat thymocytes. In the absence of IL-2, viability decreased as rapidly as without TCR stimulation. Addition of IL-2 rescued TCR-stimulated virgin DP cells and prevented CD8 downregulation, so that 50-80% of input DP cells were recovered after 2 d as CD4-8+53+ cells. After release from modulation, these in vitro generated CD8 SP cells quantitatively upregulated the TCR to the TCRhigh phenotype and were readily induced to proliferate and exhibit cytotoxic T lymphocyte (CTL) activity in a polyclonal readout. Evidence is presented implicating an IL-2 receptor (IL-2R) not containing the p55 chain (i.e., most likely the p70 intermediate affinity IL-2R) in the TCR plus IL-2-driven in vitro differentiation of virgin DP cells towards the mature CD8 SP phenotype.

Animals↗

PubMed1991

The appearance of T cells bearing self-reactive T cell receptor in the livers of mice injected with bacteria.

We demonstrated in the present study that with bacterial stimulation, an increased number of alpha/beta T cells proliferated in the liver of mice and that even T cells bearing self-reactive T cell receptor (TCR) (or forbidden T cell clones), as estimated by anti-V beta monoclonal antibodies in conjunction with immunofluorescence tests, appeared in the liver and, to some extent, in the periphery. The majority (greater than 80%) of forbidden clones induced had double-negative CD4-8-phenotype. In a syngeneic mixed lymphocyte reaction, these T cells appear to be self-reactive. Such forbidden clones and normal T cells in the liver showed a two-peak pattern of TCR expression, which consisted of alpha/beta TCR dull and bright positive cells, as seen in the thymus. A systematic analysis of TCR staining patterns in the various organs was then carried out. T cells from not only the thymus but also the liver had the two-peak pattern of alpha/beta TCR, whereas all of the other peripheral lymphoid organs had a single-peak pattern of TCR. However, T cells in the liver were not comprised of double-positive CD4+8+ cells, which predominantly reside in the thymus. The present results therefore suggest that T cell proliferation in the liver might reflect a major extrathymic pathway for T cell differentiation and that this hepatic pathway has the ability to produce T cells bearing self-reactive TCR under bacterial stimulation, probably due to the lack of a double-positive stage for negative selection.

Animals↗

PubMed1991

Reduction of lupus nephritis in MRL/lpr mice by a bacterial superantigen treatment.

The effects of biweekly intravenous injections of Staphylococcus Enterotoxin B (SEB) into autoimmune MRL-lpr/lpr (MRL/lpr) mice were investigated. Rather than causing the expansion of V beta 8+ T cells, SEB administration resulted in the reduction V beta 8+, CD4-CD8- "double-negative" (DN) T cells. This was shown by FACS analysis as this putative pathogenic population was diminished in both spleen and lymph node. The symptoms of systemic lupus erythematosus (SLE) in MRL/lpr, which include high titers of anti-DNA antibodies and circulating immune complexes and proteinuria, were reduced in SEB-treated mice in a dose-dependent manner. The clinical parameters of SLE in MRL/lpr, which include lymph node hyperplasia and necrotic vasculitis, were suppressed in 50-micrograms SEB-treated mice. T cells bearing V beta 6 T cell receptor, which does not interact with SEB, were not reduced with SEB administration. Thus, disease suppression was associated with a specific reduction in the number of V beta 8+, DN T cells. These results implicate a possible therapeutic role of superantigen-based immunotherapy in V beta-restricted, T cell-dominated clinical syndromes.

Animals↗

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↗

PubMed1991

Induction of granulocyte-macrophage colony-stimulating activity by 12-O-tetradecanoylphorbol-13-acetate in SENCAR and B6C3F1 mice.

Previous studies in this laboratory and others have indicated that 12-O-tetradecanoylphorbol-13-acetate (TPA), the most potent skin tumor promoter known, evokes significantly greater inflammatory responses in phorbol ester-sensitive (SENCAR) mice compared to strains (e.g. C57BL/6 and B6C3F1) that are relatively resistant to the outgrowth of skin tumors in two-stage chemically induced carcinogenesis protocols. In the studies reported herein, subchronic topical application of TPA at doses relevant to two-stage protocols induced serum granulocyte-macrophage colony-stimulating activity (GM-CSA) in both SENCAR and B6C3F1 mice; however, the increase in SENCAR mice was significantly greater than that observed in the relatively resistant B6C3F1 strain (5-fold versus a 2-fold increase respectively). The greater increase in serum GM-CSA observed in SENCAR mice was correlated with a 31% increase in the number of splenic leukocytes that lacked both B and T cell surface markers (i.e. double-negative cells), a presumed GM progenitor cell; no significant increase in the relative percentage of such cells was observed in B6C3F1 mice. Alternatively, significant decreases in splenic T lymphocytes (23 and 32% in SENCAR and B6C3F1 respectively) were observed in both strains of TPA-treated mice and may, in part, account for the previously observed decreases in splenic cell blastogenic response to the T cell mitogen phytohemagglutinin (PHA). In vitro incubation of splenic cells from SENCAR mice with 0.01-1.0 microM TPA led to significantly greater increases in colony formation relative to splenic cells isolated from B6C3F1 mice; therefore, differences in the biochemical responsiveness between strains may occur at the level of signal transduction in splenic GM progenitor cells. In conclusion, these studies indicated that strain-dependent differences in the systemic inflammatory response following topical application of TPA may result from direct stimulation of splenic GM precursor cells by TPA and/or may occur, indirectly, through the release of cytokines [e.g. GM colony-stimulating factor (GM-CSF)] by induced epidermal (or other) cells.

Administration, Topical↗

PubMed1991

Interplay between IL-2 and IL-4 in human thymocyte differentiation: antagonism or agonism.

The effect of recombinant interleukin 2 (IL-2) and IL-4, as well as a combination of both lymphokines on human post-natal thymocytes at different maturation stages, was analyzed by culturing highly purified pro-T cells, pre-T cells, double-negative and double-positive thymocyte subsets in the presence of IL-2 and/or IL-4. Both IL-2 and IL-4 responsiveness are developmentally regulated in human thymocytes, since IL-2 and IL-4 responses decline with increasing thymocyte differentiation, double-positive T cells displaying far less proliferation than immature thymocytes. IL-2 and IL-4 may influence pro-T cell growth in both an antagonistic and additive fashion. At low doses, IL-4 inhibits IL-2-supported growth of pro-T cells, whereas, at higher concentrations, this inhibitory effect is masked by the ability of IL-4 to stimulate pro-T cell proliferation. In contrast to peripheral lymphocytes, IL-4 does not down-regulate the expression of the IL-2 receptor light chain on thymocytes. In pro-T cell cultures, IL-2 and IL-4 favour the differentiation of distinct cell populations, namely lymphocytes displaying preferentially a TCR alpha/beta+ and CD4+CD8- phenotype versus predominantly TCR gamma/delta+ and CD4-CD8+ cells, respectively. The effect of IL-2 dominates over that of IL-4, since the composition of cultures set up in the presence of IL-2 plus IL-4 resembles that of cells cultured with IL-2 alone. In synthesis, IL-2 and IL-4 exhibit reciprocal inter-relations in human thymocyte cultures, thus supporting the notion that these lymphokines are implicated in the complex regulation of a local cytokine network.

Antigens, CD↗

PubMed1990

Analysis and characterization of the interleukin 2 receptor alpha and beta chain expression in CD4-CD8- cells.

The differential effects that the binding of interleukin 2 (IL-2) to its beta or alpha beta receptors might induce in two different CD4-CD8- T-cell lines were analysed. While LD1.T3b, a double-negative T cell derived from MRL/lpr mice, constitutively expressed high levels of the IL-2R beta chain, YAC-1, a Moloney sarcoma virus-transformed CD4-CD8- T cell, expressed (as an activated T cell) the beta and alpha chains. The presence of IL-2 in the culture medium was lethal for LD1.T3b cells, while it had no effect on the growth of YAC-1 cells. IL-2 increased the expression of the beta chain and, to a lesser extent, of the alpha chain in YAC-1 cells. In addition, other markers such as CD4 and CD5 were induced by IL-2 in this cell line.

CD4-Positive T-Lymphocytes↗

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↗

PubMed1991

Extensive analysis of lymphocyte subsets in normal subjects by three-color immunofluorescence.

In the present work, 30 normal controls were studied with 11 combinations of 3 monoclonal antibodies in order to define CD20, CD4, CD8, CD16 and CD56 subsets as well as their activation status. Our results indicated that among B cells, CD5- cells predominated (about 92%), the minor CD5+ fraction showed variations between individuals but sometimes was as high as 20% in B cells; the CD45RA+CD29- subset (naive cells) accounted for 31.56 +/- 10.03% in CD4 cells, as compared to CD4+CD29+CD45RA- (memory cells) (46.54 +/- 10.35%), while CD4+CD29+CD45RA+ (transition cells between naive and memory state) represented 9.6 +/- 5.3% as compared to double-negatives (12.3 +/- 5.24%). Some uncertainties persist in defining CD8 subsets. NK CD8 cells accounted for about 20% of total CD8 according to CD16 and CD56 expression. Cytotoxic T lymphocytes could be delineated by S6F1 (76.22 +/- 11.28% within CD8 cells), though this marker appeared to be expressed by both cytotoxic and NK cells. Phenotypic definition of suppressive CD8 cells remains uncertain despite the fact that suppressor activity was found among CD8 lymphocytes expressing CD11b and probably CD57. NK cells coexpressed CD16 and CD56 markers in about 5% of all lymphocytes, while NK cells expressing CD16 alone accounted about 6%. Exclusive expression of CD56 was found in about 5%. Finally, while activated cells characterized by DR expression represented about 4% of CD4 and 9% of CD8 cells, CD25 appeared to be poorly represented among CD4, CD8 and CD20.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗

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↗