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At least 19 recordsLinked to original sources
PubMed1986

Progenitor cells in the thymus: most thymus-homing progenitor cells in the adult mouse thymus bear Pgp-1 glycoprotein but not interleukin-2 receptor on their cell surface.

Pgp-1-positive and interleukin-2-receptor (IL-2R)-positive cells are both minor (less than 5%) subpopulations within the adult thymus. A thymocyte population enriched for these two cell types, obtained by killing the bulk of thymocytes with anti-Thy-1 antibody and complement, contains thymus-homing progenitor cells which can transiently repopulate the thymus of irradiated recipients. Using two-color immunofluorescence, we demonstrate that the Pgp-1+ and IL-2R+ cells present in this enriched population represent largely nonoverlapping subsets, although some cells do express both markers. We also show by depletion of these two cell types that the bulk of the thymus-homing progenitors present in this enriched population are found in the Pgp-1+ population, and not in the IL-2R+ population. We discuss the relationship between the thymus-homing progenitors in this depleted thymus subpopulation and the thymus-homing progenitors present in the thymus as a whole.

Animals↗
PubMed1979

Effect of cortisone and X-irradiation on cellular depletion and regeneration in the thymus of mice: experimental discrimination between thymus lymphocyte precursors in the bone marrow and in the thymus.

The effect of cortisone treatment on the ability of bone marrow cells to repopulate X-irradiated thymus was investigated. In one experimental series, groups of mice were treated first with cortisone and then irradiated with or without bone marrow protection. Mice treated with either cortisone or radiation alone served as controls. During an initial, bone marrow independent phase of thymus regeneration, cortisone had a stronger inhibitory effect on the cellular regeneration of the organ than irradiation. On the other hand, during a subsequent bone marrow dependent phase, thymus regeneration was impaired by radiation exposure but not by cortisone treatment. In another experimental series, irradiated mice were transplanted with bone marrow cells in different numbers from syngeneic donors which had either been treated with cortisone or were left untreated. Twenty days later the cell number was consistently larger in the thymus of animals which has been transplanted with cortisone treated bone marrow than in the animals transplanted with untreated bone marrow. It is concluded that the thymus lymphocyte precursors in the bone marrow and the early precursors of thymocytes in the thymus differ with regard to their sensitivity to cortisone and radiation and, therefore, may represent two distinct cell types.

Animals↗
PubMed1983

[Physiological dependency between the hypothalamus and the thymus in Wistar rats. III. Hypothalamic cells cultured in vitro in the presence of Thymus Factor X (TFX) and fresh thymus filtered homogenate].

The studies were carried out on the hypothalamic cells cultured in vitro in the presence of low-molecular proteins (constituting the control): the thymic hormone, known as Thymus Factor X [TFX]; or fresh thymus filtered homogenate prepared from the glands collected from 1 h or 7 d old rats. All the cultures were supplemented with 3H-thymidine. The experiments demonstrated that TFX in when added to the culture caused a decrease 3H-thymidine synthesis in comparison to the control. In other cultures, which were enriched with the fresh thymus filtrated homogenate, especially from 7 d old rats, a high level of thymidine synthesis in the cellular nuclei was observed.

Animals↗
PubMed1980

[Effect of substances of a polypeptide nature isolated from the thymus and cerebral cortex on the primary immune response of mice to thymus-dependent and thymus-independent antigen].

The study of the effect of low molecular polypeptides on the primary immune response induced in CBA mice by the injection of thymus-dependent antigen (SRBC) and thymus-independent Vi-antigen showed that the injection of the preparation obtained from the cerebral cortex (cortexin) or the thymus (thymarin) for 5 days before and for 3 days after SRBc immunization stimulated the production of both direct (IgM) and indirect (IgG) antibody-producing cells, as well as the production of hemagglutinins. At the same time the production of antibody-producing cells and antibodies to Vi-antigen was suppressed. The preparations of white cerebral tissue and red bone marrow produced no effect on immune response in the animals.

Animals↗
PubMedDate not supplied

[Activity of lysosomal proteinases in the liver, spleen, thymus and peritoneal macrophages after immunization of mice with thymus-dependent and thymus-independent antigens].

Mice of the CBAxC97B/6 strain were immunized with sheep erythrocytes at a dose of 0.5 ml containing 5% and 25% of the cell suspension and with Vi-antigen at doses of 2 micrograms/ml and 10 micrograms/ml, respectively. Sheep erythrocytes caused dose-dependent stimulation of cathepsin B, C and H in spleen, whereas cathepsin B was activated 3.1-3.6-fold after administration of Vi-antigen. Functional state of the lysosomal proteolytic system did not alter in thymus in response to sheep erythrocytes, while Vi-antigen activated distinctly thiol-dependent proteinases. In peritoneal macrophages administration of sheep erythrocytes led to 2-5-fold decrease in activity of all the lysosomal proteinases studied (cathepsins A, B, C, D, H and L), however Vi-antigen exhibited direct dose-dependent effect on activity of cathepsins A, B, D and L. The data obtained suggest that T-independent reactions of the immune system were realized via thiol-dependent lysosomal proteinases.

Animals↗
PubMed1981

The H-2 phenotype of the thymus dictates the self-specificity expressed by thymic but not splenic cytotoxic T lymphocyte precursors in thymus-engrafted nude mice.

The present study was performed to examine the specificity of the self-recognition repertoire expressed by TNP-specific CTL precursors present in the thymus and the spleen of congenitally athymic nude mice engrafted with either semiallogeneic or fully allogeneic neonatal thymuses. It was shown that the engrafted thymus lobes were fully repopulated with cells of nude host origin and that the engrafted thymus tissue was capable of reconstituting peripheral CTL function in the nude host. Assessing the specificity of the lymphocytes differentiating within the thymus graft, the present study revealed that CTL precursors of nude host origin in the thymus grafts were nonalloreactive to both nude-host-type and thymus-type MHC determinants but were invariably restricted to the self-recognition of thymus-type, not nude-host-type, MHC determinants. Furthermore, the restricted self-recognition of thymic MHC determinants was not mediated by detectable suppression. In contrast to the restricted self-recognition repertoire of CTL precursors in the thymus of these mice, CTL precursors from the spleens of the same mice were not restricted to the self-recognition of thymus-type MHC determinants but instead recognized TNP in association with both host and thymus-type MHC determinants. These data demonstrate that at least in thymus-engrafted nude mice the self-recognition repertoire of thymocyte CTL, but not spleen CTL, is entirely dictated by the MHC phenotype of the thymus tissue in which they differentiate. It is proposed that the spleen CTL repertoire in these mice reflects the coexistence of at least 2 CTL subpopulations, 1 that differentiated within the engrafted thymus and 1 that differentiated outside the engrafted thymus.

Animals↗
PubMed1986

Primary cultures of human myasthenia gravis thymus and normal thymus. Studies of cell morphology, cell proliferative pattern and localization of alpha-bungarotoxin binding sites on cultured thymic cells.

We have established primary cultures of human myasthenia gravis (MG) thymuses and normal thymuses. In cultures of 19 thymuses with hyperplasia among 23 MG thymuses and 12 thymuses among 13 normal thymuses, epithelial cells migrated in a mosaic-like arrangement and were maintained for more than 5-10 weeks. There were, among mononuclear epithelial cells, some multinucleated cells, some of which were considered to be derived from epithelial cells because they had a desmosome-like structure and contained tonofilaments in their cytoplasm. There was no significant difference in the morphology of epithelial cells between MG thymuses and normal thymuses. The growth rate of thymic epithelial cells was identified by [3H]thymidine autoradiography(ARG), labeling indices rising to a peak around a week and falling to low levels gradually. There was no significant difference in the growth rate of epithelial cells between MG thymuses and normal thymuses. An autoradiographic method with 125I-labeled alpha-bungarotoxin was used to detect the presence of acetylcholine receptor (AChR) on the cultured cells. ARG of human MG thymuses and normal thymuses, which were cultured for 4 weeks, revealed diffusely distributed silver grains on the epithelial cells. Toxin binding sites (AChRs) were considered to be present on the epithelial cells. There was no significant difference in the distribution of AChR on the epithelial cells between MG thymuses and normal thymuses.

Adolescent↗
PubMed1975

The effect of the thymus-independent antigens, collagen and synthetic collagen-like polypeptide, on the requirement of cell cooperation in the immune response to thymus-dependent antigens.

The effect of thymus-independent antigens on the need for cell cooperation in the immune response to thymus-dependent antigens was investigated. Irradiated recipient mice transplanted with either bone marrow cells or a mixture of bone marrow and thymus cells, were immunized with the thymus-independent antigen (Pro-Gly-Pro)n covalently conjugated to the thymus-dependent ovalbumin, or with a mixture of (Pro-Gly-Pro)n and ovalbumin. In both cases an effective response towards ovalbumin was observed in the absence of thymus cells as was found for the thymus-independent (Pro-Gly-Pro)n. The same effect on ovalbumin was demonstrated when a mixture of the thymus-independent collagen and ovalbumin was used for immunization. On the other hand, when irradiated reconstituted mice were immunized with a mixture of ovalbumin and the thymus-dependent gelatin, which is the denatured product of collagen, cell-to-cell cooperation was required for an immune response to both immunogens. The effect of (Pro-Gly-Pro)n and collagen on the response to the thymus-dependent ovalbumin in vivo was observed in in vitro experiments using sheep red blood cells (SRBC) as the immunogen as well. In the presence of reduced and carboxymethylated (RCM) Ascaris collagen and (Pro-Gly-Pro)n, nude spleen cells could produce significant numbers of plaque-forming cells towards SRBC. Thus, (Pro-Gly-Pro)n and collagen can deliver the signal required to stimulate B cells to produce antibody towards thymus-dependent antigens in the absence of T cells. In contrast to the results with (Pro-Gly-Pro)n and collagen, the thymus-independent synthetic polypeptide poly(DTyr, DGlu-)-poly(DPro)--poly(DLys) did not affect the requirement for cell cooperation of the thymus-dependent immunogens, ovalbumin and SRCB. It thus appears that the ability to substitute for T cells for antibody production towards thymus-dependent immunogens is not a general characteristic of thymus-independent antigens.

Animals↗
PubMed1978

B-lymphocyte colony-forming cells in the SJL/J mouse thymus graft repopulation: independence on host thymus and graft genotype.

We have studied the development of B-lymphocyte colony-forming cells (BL-CFC) in SJL and A.SW mouse thymus grafts transplanted into lethally irradiated A.SW mice protected with SJL mouse bone marrow (A.SW-SJL bone marrow chimaeras). The chimaeric state was confirmed by Ly allotype analysis. High incidence of BL-CJC was found in both the A.SW and the SJL thymus grafts, indicating that SJL bone marrow generates BL-CFC, or cells capable of generating BL-CFC, with a high affinity for homing in the thymus irrespective of the genotype of the thymus reticulum. The incidence of BL-CFC in the SJL thymus grafts, however, was approximately 20 times higher than the incidence of BK-CFC in the A.SW thymus grafts. Thus, the extensive infiltration of ageing SJL thymus glands by BL-CFC demonstrated recently is caused not only by SJL bone marrow B cells with a high affinity for thymus homing but also by the specific property of the SJL thymus environment. The extensive infiltration of syngeneic thymus grafts by BL-CFC observed in ageing SJL mice was found to occur independent of an intact host thymus function, indicating the extrathymic origin of these cells.

Animals↗
PubMed2000

Thymus and lymph node cell CD4(+) and CD8(+) marker expression and their angiogenic activity of offspring of salbutamol-treated pregnant C3H mice.

Salbutamol, beta(2)-adrenoceptor agonist is a first choice drug in preterm delivery treatment. The aim of the present study was to determine whether salbutamol can cause any alterations in neonatal immune systems and therefore should be considered in newborn care. The experiments were performed on 4-5- and 6-7-week-old female and male offspring of salbutamol-treated C3H inbred mice. Thymus and lymph node weight, cellularity and lymphatic organs, lymphocytes phenotypes and their angiogenic activity were evaluated. We observed lower thymus weight in 6-7-week-old progeny of salbutamol-treated mothers and in the same time lower thymus cell number in both age groups. Lower lymph node weight was developed in older progeny while cellularity was diminished both in 4-5- and 6-7-week-old offspring of salbutamol-treated mothers. We have not detected any changes in percentage of CD4, CD8, CD3 and CD4CD8 positive lymphocytes in progeny of salbutamol-treated mothers. As far as lymph node lymphocytes phenotype is considered we showed in both age groups lowering of CD4 and CD3 positive cells in experimental groups. In the LIA test (lymphocyte-induced angiogenesis) we showed lower lymph node cell angiogenic activity of salbutamol-treated mothers' progeny in both age groups. In the case of thymus lymphocytes we have not observed any alterations in their angiogenic activity. The differences in histological examination of thymus and lymph nodes were not detected in experimental and control groups.

Adrenergic beta-Agonists↗
PubMed1988

Intra- and extrathymic B cells in physiologic and pathologic conditions. Immunohistochemical study on normal thymus and lymphofollicular hyperplasia of the thymus.

Normal thymuses and thymuses with lymphofollicular hyperplasia have been examined immunohistologically using immunoenzymatic single and double labelling methods and a panel of monoclonal antibodies against B lymphocyte differentiation antigens (CD19-, CD20-, CD21-, CD22-, CD23- and CD37ag) and human immunoglobulins (IgM, IgD) for the presence and localisation of B lymphocytes and cells expressing B cell differentiation antigens. The numerous hyperplastic lymph follicles which occur in the pathological condition of lymphofollicular hyperplasia of the thymus were found to originate in the extrathymic compartment of the interlobular septal space. This area was found to be blown up by the growing lymph follicles with exactly the same cellular composition as their counterparts in the peripheral lymphatic tissue. Some of the B lymphocytes expressing the immunophenotype of follicular mantle zone lymphocytes which were detected in the thymic medulla probably infiltrated through discontinuities of the border between the perivascular space and the thymic medulla. Apart from this primarily extrathymic B cell compartment, B lymphocytes and cells expressing B cell antigens were found within the thymus medulla of normal control thymuses of different ages from fetal to adult life. These cells were detected as a small subpopulation in normal fetal, juvenile and adult thymuses. Morphologically they could be subdivided into small, round lymphoid cells accounting for less than 1% of medullary lymphoid cells, and into a larger variant, asteroidally shaped because of short cytoplasmic processes. These asteroid cells were even more infrequent than the lymphoid variant. Immunophenotype (CD19ag+, CD20ag+, CD22ag+, CD37ag+, IgM+, IgD+) and morphology of the first cell type led to the conclusion that the lymphoid cells were in fact B lymphocytes. They were scattered throughout the medulla of fetal and juvenile and adult thymuses alike. The second, the asteroid cell type, constantly expressed CD20ag and inconstantly IgM, CD22ag and CD37ag; furthermore, CD23ag was detected in a subset of the asteroid cells either restricted to the perinuclear zone or expressed in the entire cytoplasma and on the plasma membrane. The asteroid cells were located in the corticomedullary region of the fetal thymuses but were randomly distributed with a tendency to Hassall's corpuscles in juvenile and adult thymuses. They often formed rosettes with non-B lymphocytes.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1982

Restoration of T cell depression and suppression of blood pressure in spontaneously hypertensive rats (SHR) by thymus grafts or thymus extracts.

Spontaneously hypertensive rats (SHR) that develop hypertension and arterial lesions resembling human periarteritis nodosa were found to possess a selective depression of T cell functions with an appearance of natural thymocytotoxic autoantibody (NTA). The relationship between T cell depression and hypertension in these animals was investigated. The immune responsiveness of T cell-depressed SHR was completely recovered by histocompatible thymus grafts and was partially restored by histoincompatible allogeneic or xenogeneic thymus grafts or by injection of thymus extracts. Transplantation of compatible thymus tissues into neonatal SHR produced long-lasting recovery of immune functions. When complete immunologic restoration was achieved, significant suppression of high blood pressure was obtained. The SHR that showed high blood pressure were always accompanied with high NTA titers and arterial lesions. Thymus grafts or thymus extracts significantly decreased the titers of NTA. The development and dissemination of arterial lesions, which may cause increased blood flow resistance, were completely prevented by compatible thymus grafts into neonatal SHR. These results suggest that thymus grafts and thymus extracts may suppress the development of hypertension by preventing or curing the periarteritis nodosa in SHR.

Aging↗
PubMed1991

Modulation of B cell maturation and migration to the thymus of SJL mice. B cell migration to the thymus.

The direct linkage of the B cell maturation process and infiltration of the thymus with mature B cells was studied in SJL mice. Phenotypically and functionally, B cells in the thymus of old SJL mice are mature B cells; IgM+, IgD+, Ly-1-, and evince a high proliferative response to lipopolysaccharide and a low one to dextran sulphate. Memory B cells can be found in the thymus of mice immunized with T-dependent or T-independent antigens. Chronic depletion and B cell maturation arrest induced by fractionated total lymphoid irradiation or by neonatal splenectomy eliminate B cells from the thymus and block their migration from the periphery to the thymus. When examined in adoptive transfer experiments, thymus B cells were found to possess a normal migration pattern and homing receptors; their migration pattern did not differ from that of lymph node or splenic B cells. It is evident, therefore, that the large number of normal functioning B cells in the thymus of SJL mice reflects a massive infiltration of the thymus by mature B cells from the periphery due to thymus dysfunction rather than to an abnormal in situ differentiation of intrathymic B cell precursors.

Animals↗
PubMed1988

Thymus-dependent and thymus-independent developmental pathways for peripheral T cell receptor-gamma delta-bearing lymphocytes.

To elucidate the developmental pathways of T cells that bear TCR gamma delta, we have analyzed the kinetics of expression and biochemical characteristics of gamma delta receptors in the thymus and spleen of normal and athymic (nude) mice, as well as nude mice engrafted with neonatal thymuses. TCR gamma delta-bearing thymocytes and splenocytes have a CD4-8- phenotype, and both populations express products of the C gamma 1 locus. TCR gamma delta-bearing cells develop in the thymus before their appearance in the spleen. Young nude mice have no detectable TCR gamma delta-bearing cells in their spleens. When young nude mice are given thymus grafts, TCR gamma delta-bearing cells of host origin first develop in the engrafted thymus, followed by their appearance in the spleen. In the absence of a thymus graft, the spleens of old nude mice eventually develop small numbers of TCR gamma delta + cells, as well as TCR alpha beta + cells. These results demonstrate that there is a major thymic-dependent pathway for TCR gamma delta expression, as well as a minor thymic-independent pathway seen in older nude mice. The development of TCR gamma delta + cells in the thymus before their appearance in the spleen, both in normal ontogeny as well as in the thymus-engrafted nude mouse model, suggests that thymic TCR gamma delta + cells are precursors of the thymus-dependent population of peripheral TCR gamma delta + cells.

Aging↗
PubMedDate not supplied

[The effect of the local irradiation of areas of the thymus, hypothalamus/hypophysis and gonads in mice on the cellularity of the autologous and transplanted thymus].

Mice were grafted with syngeneic neonatal thymus 1-3 days or 7.5-8 months after local irradiation of thymus, hypothalamus/hypophysis and gonads. Thymus weight and thymocyte number were measured in autologous and grafted thymus 35-40 days after the transplantation. Thymus transplantation induces significant decrease in weight and cellularity of both autologous and grafted thymus. Irradiation of autologous and grafted thymus in doses of 1 and 10 Gy abrogates this effect. Irradiation of hypothalamus/hypophysis and gonads induces decrease of weight and cellularity of autologous and grafted thymus. Irradiation of gonads does not abrogate inhibitory effect of thymus transplantation. Local irradiation of all three regions decreases titre of serum thymic activity and influence concentrations of some hypophysis and adrenal hormones.

Animals↗
PubMedDate not supplied

[Dynamics in changes of a1-thymosin level under irradiation of mice thymus in vivo and in vitro: relation to the antibody-antigen production of epithelial thymus reticulum].

In 3- and 9-month experiments with mice, a study was made of the effect of radiation on serum alpha 1-thymosine concentration after whole-body irradiation and local exposure of the thymus at doses of 1-20 Gy. The effect of 137Cs-gamma-rays on the in vitro cultured thymus stroma cells, with respect to alpha 1-thymosine secretion, and the influence of local irradiation of the thymus of production of autoantibodies that react with epithelial thymus cells were studied. Both whole-body irradiation and local exposure of the thymus were shown to cause changes in the alpha 1-thymosine content of the blood plasma. The direction and dynamics of the changes observed are different with whole-body and local exposure. Irradiation of cultured thymus cells of mice causes alterations in alpha 1-thymosine secretion, that is, stimulation at a dose of 1 Gy and inhibition at higher doses. With respect to dose- and time-response, these changes are closer to those observed in alpha 1-thymosine concentration in mouse serum after whole-body irradiation than after local exposure of the thymus in vivo. At remote times after local irradiation of the thymus with doses of 1-10 Gy, autoantibodies are found in mouse serum that react with epithelial cells of the thymus stroma. Autoantibodies are absent at doses of 15 and 20 Gy.

Animals↗