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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↗

PubMed1991

Clonal deletion and autoreactivity in extrathymic CD4-CD8-(double negative) T cell receptor-alpha/beta T cells.

Peripheral CD4-CD8- (double negative) T cells (DNT cells) that express TCR-alpha/beta (DNT-alpha/beta cells) are expanded in some autoimmunity-prone mice, but in normal mice these cells have not been extensively studied. In this study, we isolated splenic DNT-alpha/beta cells that are Thy-1+, Ly-1+, MAC-1-, J11d-, and Ia-. Only 5% of these cells were B220+. Freshly isolated DNT-alpha/beta cells did not proliferate in MLC; however, these cells responded strongly to stimulation with matrix-bound anti-TCR-alpha/beta antibodies or Con A. After activation the cells became CD4+CD8-, acquired high reactivity in both syngeneic and allogeneic MLC, but lacked cytotoxicity. After activation the cells gradually reverted to a double-negative phenotype in culture. Surprisingly, despite high autoreactivity the analysis of TCR V beta expression revealed a near normal pattern of Mls-1a- and I-E-induced clonal deletions. These findings reveal that DNT-alpha/beta cells are subject to negative selection and that autoreactivity cannot be attributed to a general failure of clonal deletion in this T cell subpopulation. DNT-alpha/beta cells may normally remain tolerant by down-regulating the CD4 molecule.

Animals↗

PubMed1990

Growth of immature (double negative) rat thymocytes in the presence of IL-1.

It is unclear which growth factors, if any, are involved in the growth and differentiation of immature T cells in the thymus. Because IL-1 has been previously implicated in thymocyte proliferation, we examined the effects of IL-1 on precursor thymocytes, the CD4-CD8- or double-negative (DN) cells. We show that IL-1 (together with Con A) is a growth factor for DN, TCR- alpha beta-cells in vitro. After 5 days of culture in IL-1 and Con A, a number of phenotypic changes were observed and two subsets of DN cells were distinguished. One subset expressed full length TCR-alpha and -beta mRNA and surface alpha beta TCR, the other expressed low levels of full length TCR-gamma together with high levels of full length TCR-delta mRNA. Thus, DN cells are induced by IL-1 and Con A to proliferate and express TCR without parallel acquisition of CD4 or CD8 markers. These data suggest that IL-1 drives early steps of intrathymic T cell differentiation.

Animals↗

PubMed1990

In vitro differentiation from a pluripotent human CD4+CD8+ thymic cloned cell into four phenotypically distinct subsets.

Human thymic cell differentiation is almost totally unknown. In the present study we developed an in vitro system using human thymic cloned cells to analyze precursor-progeny relationship. We obtained several CD4+CD8+ double positive thymic clones that could give rise after several weeks in culture only to either CD4 or CD8 single positive clones. By contrast we isolated a unique pluripotent thymic double positive clone, termed B12, which differentiated into four phenotypically distinct T cell clones, namely double-positive CD4+CD8+, double-negative CD4-CD8- or either single-positive phenotype. We derived stable subclones representative of each phenotype and we showed by molecular analysis that they expressed the same TCR. Utilization of either CD3 or anticlonotypic mAb revealed that this TCR expressed by the four subclones was functional.

Antigens, CD↗

PubMed1991

In vivo stem cell function of interleukin-3-induced blast cells.

The treatment of mice with high doses of 5-fluorouracil (5-FU) results in an enrichment of primitive hematopoietic progenitors. Using this procedure, we obtained a new class of murine hematopoietic colonies that had very high secondary plating efficiencies in vitro and could differentiate into not only myeloid cells but also into lymphoid lineage cells. The phenotypes of interleukin-3 (IL-3) induced blast colony cells were Thy-1-positive and lineage-marker-negative. We examined whether these blast colony cells contained primitive hematopoietic stem cells in vivo and could reconstitute hematopoietic tissues in lethally irradiated mice. Blast colony cells could generate macroscopic visible spleen colonies on days 8 and 12, and 5 x 10(3) blast cells were sufficient to protect them from lethally irradiation. It was shown that 6 or 8 weeks after transplantation of 5 x 10(3) blast cells, donor male cells were detected in the spleen and thymus of the female recipients but not in the bone marrow by Southern blot analysis using Y-encoded DNA probe. After 10 weeks, bone marrow cells were partially repopulated from donor cells. In a congenic mouse system, donor-derived cells (Ly5.2) were detected in the thymus and spleen 6 weeks after transplantation. Fluorescence-activated cell sorter analyses showed that B cells and macrophages developed from donor cells in the spleen. In the thymus, donor-derived cells were found in CD4, CD8 double-positive, single-positive, and double-negative populations. Reconstitution of bone marrow was delayed and myeloid and lymphoid cells were detected 10 weeks after transplantation. These results indicate that IL-3-induced blast cells contain the primitive hematopoietic stem cells capable of reconstituting hematopoietic organs in lethally irradiated mice.

Animals↗

PubMed1990

Purification and characterization of intraparenchymal lung lymphocytes.

We analyzed phenotypic and functional characteristics of intraparenchymal pulmonary lymphocytes in mice. As determined by flow cytometry, approximately 30% more T cells than B cells were found. Nearly all T cells bore the alpha beta TCR, most of which stained with either CD4+ or CD8+, although small numbers of double-negative T cells were present; the CD8+/CD4+ ratio was approximately 0.37. While practically all B cells bore surface IgM, and no IgA+ cells were found, and approximately more than 80% of the plasma cells produced IgA. Approximately half of the LPS-responsive cells produced IgA. Pulmonary B cell clonal precursors specific for the autoantigen, transferrin, were present in higher frequencies than those specific for the bacterial antigens, levan and Pseudomonas aeruginosa polysaccharide type I, or those producing antibodies against OVA. These results demonstrate that a distinct population of lymphocytes is present in the lungs.

Animals↗

PubMed1990

Evidence for CD8-independent T cell maturation in transgenic mice.

Double-negative (CD4-/CD8-) T cells expressing the alpha/beta transgenic TCR from the 2C cell line (anti-H-2Ld) were examined in the periphery of animals whose MHC type produces positive, negative, or no selection for differentiation of the TCR on single positive (CD8+) cells. Regardless of the selection haplotype the CD4-/CD8- cells are capable of activation by anticlonotypic mAb indicating that negative selection does not inactivate the "forbidden" TCR. Rather, the lack of response to H-2Ld in the negative haplotype is likely to absence of CD8 required to produce a functional response to H-2Ld. The similarity of surface phenotype and functional activity of these CD4-/CD8- cells maturing in different haplotypes suggests they may arise by an alternative lineage which, unlike the dominant TCR alpha/beta pathway, does not require coexpression of CD4/CD8.

Animals↗

PubMed1990

Human cytotoxic lymphocytes. V. Frequency and specificity of gamma delta+ cytotoxic lymphocyte precursors activated by allogeneic or autologous stimulator cells.

We have investigated the frequency and specificity of gamma delta+ cytotoxic lymphocyte precursors (CLP) under limiting dilution culture conditions. E rosette separated total T cells and CD3+CD4-CD8-TCR alpha beta- double-negative (DN) T cells were cocultured with allogeneic or autologous PBMC stimulator cells, and frequencies of alloreactive and autoreactive CLP were determined after 12 to 14 days against Con A blast target cells. Freshly isolated DN cells consisting of 82.3 +/- 8.2% gamma delta+ T cells did not exert cytolytic activity against K562 or anti-TCR gamma delta mAb-producing hybridoma cells. In striking contrast to E+ cells, the vast majority of alloantigen-stimulated clonally developing DN CLP did not show specificity for stimulator-derived target cells. Thus, frequencies of alloreactive and autoreactive CLP after alloantigenic stimulation were in the range of 1/100 to 1/4800 and 1/450 to 1/5000, respectively. After coculture with autologous stimulator cells, frequencies of autoreactive and alloreactive DN CLP were 1/700 to 1/2700 and 1/1360 to 1/4500, respectively. Split culture analysis revealed that most proliferating DN colonies selected for high probability of clonality simultaneously killed both autologous and HLA-mismatched allogeneic targets. The majority of the DN cells expressed the CD3+/TCR gamma delta+ phenotype after culture, and thus were not CD2+CD3- NK cells. Taken together, our results show that 1) freshly isolated peripheral blood gamma delta+ T cells lack cytotoxic activity, and 2) most cytotoxic gamma delta+ T cells activated by autologous or allogeneic stimulator cells under limiting dilution conditions do not discriminate between autologous and allogeneic targets.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1990

CD45RA is detected in all thymocyte subsets defined by CD4 and CD8 by using three-colour flow cytometry.

In the mouse, using three-colour flow cytometry, the presence of CD45RA+ cells is demonstrated amongst all of the thymocyte subsets defined by expression of CD4 and CD8, i.e. amongst the double negatives, immature CD8 single positives, double-positive blasts and CD4 and CD8 single positives. This evidence is compatible with the existence of a continuous lineage of T cells expressing CD45RA which would develop from double-negative to mature single-positive T cells.

Aging↗

PubMed1988

Mouse melanoma antigen recognized by Lyt-2- and L3T4- cytotoxic T-lymphocytes.

A mouse melanoma (B16) antigen was investigated at a cellular level by three blocking experiments using monoclonal antimelanoma antibodies, soluble melanoma antigen, and enzyme-treated B16 melanoma cells as inhibitors. The activity of antimelanoma cytotoxic T-lymphocytes (CTL) was specifically reduced by addition of the mixture of two monoclonal antimelanoma antibodies, one (M2590) recognizing the cross-species melanoma epitope on GM3(NeuAc) and the other (M562) reactive with the mouse melanoma-specific epitope on protein molecules. The CTL activity was also blocked by GM3 liposome as well as by the soluble antigen. However, 3,000 times more GM3 than the soluble melanoma antigen is required to obtain a similar inhibitory effect. When pronase-treated B16 melanoma cells, which have had protein molecules removed but GM3 left intact on the surface, were used as an inhibitor, their blocking activity was greatly reduced but was still partly observed at a high inhibitor/target ratio. These results indicate that the melanoma antigen is not GM3 itself but is composed of the GM3-protein complex. This finding was also supported by using an interleukin 2-dependent CTL clone whose activity was blocked by both M562 and M2590. Antimelanoma CTL were found to belong to a double-negative T-cell population with Thy-1+, Lyt-2-, L3T4- phenotypes. L3T4+ T-cells were also demonstrated to be necessary for induction of double negative antimelanoma CTL.

Animals↗

PubMed1988

Escape mechanisms of melanoma from immune system by soluble melanoma antigen.

We demonstrate in the B16 melanoma (C57BL/6 derived) system that the soluble form of tumor Ag preferentially suppresses immune responses 1) by inhibiting CTL activity in the effector phase and 2) by induction of specific Ts that block CTL generation in the induction phase. Soluble melanoma antigen Ag injected i.p. into the tumor-bearing host can effectively augment melanoma growth in vivo. Two T cell types with the L3T4+ or double-negative/I-J+ phenotype are involved in the suppression of anti-melanoma CTL responses and can easily be generated in the in vitro primary 12 h-culture. Anti-melanoma Ts recognizes the GM3(NeuAc) structure and distinguishes GM3 molecular species. This is because liposomes constructed with GM3(NeuAc) but not with GM3(NeuGc) gangliosides alone can effectively induce the melanoma-specific Ts. It is thus likely that tumor cells can escape from the immunologic surveillance system by stimulating the repertoire of Ts for self-Ag, GM3, which has existed even in the unprimed conditions in order to maintain self-tolerance. These would appear to be the major escape mechanisms.

Animals↗

PubMed1989

Characterization of colony-forming cells in the human thymus: evidence for a suppressor mechanism.

Activation pathways for thymic cell growth remain partially unknown. Thymocytes generally show low growth responses when cultured in the presence of mitogens, especially when T-cell colony formation by these cells is assayed. In the present work we studied the T-cell colony-forming ability of thymic subsets under phytohemagglutinin (PHA) and/or recombinant interleukin 2 (rIL2) stimulation. Our results confirm the low number of T-cell colonies obtained from human thymus as compared to bone marrow and peripheral blood sources. In contrast, significant colony numbers were observed when thymocytes were depleted of CD8+ cells. This increase was due to the suppression exerted by CD8+ cells on both CD4+- and CD4- -, CD8- -derived colony precursors. This inhibitory mechanism is dose-dependent and cannot be replaced by media conditioned by CD8+ cells. Limiting dilution analysis corroborates agar assays and points to the existence of T-cell colony-forming cells within the double-negative (CD4-, CD8-) thymic subset.

Antibodies, Monoclonal↗

PubMed1989

Immunoregulatory function of CD3+, CD4-, and CD8- T cells. Gamma delta T cell receptor-positive T cells from nude mice abrogate oral tolerance.

Previous work has shown that abrogation of oral tolerance is mediated by T cells which are found in the CD3+, L3T4- (CD4-), and Lyt-2- (CD8-) subset (termed double-negative; DN) in mice. Inasmuch as it is known that athymic, nude (nu/nu) mice possess Thy 1+, CD4-, and CD8- T cells which also exhibit a functionally rearranged TCR gamma-chain, we investigated whether this subset of nude T cells contained functional immunoregulatory cells. In this report, we examined the phenotype and distribution of CD3+ T cells in the spleen and in the mesenteric and peripheral lymph nodes of BALB/c nu/nu mice in comparison with normal mice (+/+). In the spleens of nude mice, the predominant CD3+ T cell subpopulation was DN. Further, in mesenteric and peripheral lymph nodes, approximately one-third and one-half of the CD3+ T cells were double negative, respectively. In contrast, CD3+, DN T cells represent a small subpopulation in normal (+/+) mice. We next showed that functional regulatory T cells which possess the ability to abrogate oral tolerance were induced in nu/nu mice by Ag priming. BALB/c nude mice were immunized with SRBC, and the splenic CD3+, Vicia villosa-adherent cells were obtained by panning. Adoptive transfer of CD3+, V. villosa-adherent T cells to orally tolerant BALB/c mice restored responsiveness to SRBC, whereas V. villosa nonadherent cells were without effect. In other experiments, CD3+ T cells from the spleens of SRBC-primed mice were further enriched for the CD5+, DN phenotype and adoptive transfer of this subset completely abrogated oral tolerance to SRBC. To characterize the nature of the TCR expressed on these CD3+, DN T cells, we developed a rabbit antibody to a synthetic peptide (residues 209-218: Tyr-Ala-Asn-Ser-Phe-Asn-Asn-Glu-Lys-Leu) which was synthesized from a deduced sequence of the murine delta-gene. Immunoprecipitation of a cell membrane fraction from CD3+, DN T cells with anti-delta TCR antibody isolated a 45-kDa band. Furthermore, immunoprecipitation of these cells with anti-CD3 (145-2C11) revealed bands at 45 and 35 kDa (corresponding to delta- and gamma-chains, respectively). Taken together, these results are the first to show that gamma delta-TCR bearing CD3+, CD4-, and CD8- T cells are functional and reverse oral tolerance when adoptively transferred.

Administration, Oral↗

PubMed1989

Organotin-induced thymus atrophy concerns the OX-44+ immature thymocytes. Relation to the interaction between early thymocytes and thymic epithelial cells?

After single oral application of the organotin compound di-n-butyltindichloride (DBTC) to rats, a reversible dose-dependent thymus weight reduction is observed. This is maximal at day 4 and recovers to the control value approximately at day 9 after administration. In this study the changes in thymocyte subpopulations after a single oral dose of 15 mg DBTC/kg body weight were analysed by immunohistology. Thymus glands of exposed rats were collected at day 1,2,3,4,5,7 and 9 after DBTC dosing and frozen sections were screened for various thymocyte differentiation antigens. Staining by mAb HIS-44 that labels a subset of cortical thymocytes showed that the thymus atrophy was restricted to the cortex. Here a time-dependent decrease of labelling by CD2 (OX-34), CD8 (OX-8), CD4 (ER-2), and CD5 (OX-19) was observed. In contrast, the number of cortical OX-44+ cells increased from day 2 to day 5. This increase can reflect an increase of CD4-CD8- double-negative thymocytes or of macrophages. However, most of these OX-44+ cells were negative for acid phosphatase, which is present in most macrophages. We concluded that these OX-44+ cells were mainly CD4-CD8- thymocytes and that the thymocyte subpopulation of this phenotype, i.e. CD4-CD8-OX-44+, may be the target cell for DBTC. It is discussed whether DBTC might disturb the interaction of early thymocytes and thymic epithelium, probably by an interaction with the CD2 antigen.

Animals↗

PubMed1989

Tissue localization and CD8 accessory molecule expression of T gamma delta cells in humans.

In this study, we used TCR isotype-specific antibodies to examine the frequency, phenotype, and histologic localization pattern of T gamma delta cells in humans. The TCR delta 1+ cells comprised an average of 15% of the splenic CD3+ cells and 7% of circulating T cells. The T gamma delta cells in these human tissues, like their avian counterparts, were often not "double-negative" for the CD4 and CD8 accessory molecules. Approximately 50% of the splenic delta+ cells expressed CD8, and 30% of the delta+ cells in blood were CD8+. T cells of both gamma delta and alpha beta TCR isotypes were exceedingly rare in the skin. The T gamma delta cells exhibited preferential homing to the sinusoidal areas (red pulp) of the spleen and into the epithelial layer of the intestine in humans, as had been previously noted in chickens. Although 80% of the T gamma delta cells in the human intestinal mucosa were localized in the epithelial layer, these cells represented only 5 to 10% of all the CD3+ T cells in this microenvironment. We conclude that T gamma delta cells represent a sizeable subpopulation of the T cells in human peripheral tissues. The phylogenetic conservation of the CD8 expression by peripheral T gamma delta cells and of their preferential homing pattern suggests a special role in bodily defense for this T cell subpopulation.

Aged↗

PubMed1985

Influence of cyclic AMP and hydrolysis products on cell type regulation in Dictyostelium discoideum.

We describe the effect of cyclic AMP on regulation of the proportion of prespore and prestalk cells in Dictyostelium discoideum. Prespore and prestalk cells from slugs were enriched on Percoll density gradients and allowed to regulate in suspension culture under 100% oxygen. The transition of prespore to prestalk cells is blocked by cAMP, while cAMP phosphodiesterase and caffeine cause a decrease in the number of prespore cells. This suggests that extracellular cAMP plays a role in cell type proportioning by inhibiting the conversion of prespore to prestalk cells. Low concentrations of cAMP prevent the conversion of prestalk to prespore cells; the same effect is seen with hydrolysis products of cAMP, 5 AMP, adenosine and also adenine. We suggest that, when low concentrations of cAMP are added to regulating cells, the cAMP itself is quickly broken down and the breakdown products thereafter inhibit the prestalk-to-prespore conversion. The relevance of these findings is discussed in the context of an non-positional double-negative feedback model for cell type homeostasis.

3',5'-Cyclic-AMP Phosphodiesterases↗