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D L Greiner

Publications and source records attributed to D L Greiner.

142 records · Page 8Linked to original sources
PubMed1984

Identification of thymocyte progenitors in hemopoietic tissues of the rat. I. A quantitative assay system for thymocyte regeneration.

A quantitative adoptive transfer system is described which can be used to precisely monitor the generation of thymocytes and peripheral T cell subsets by precursor cells in hemopoietic tissues of rats. This assay utilizes the rat pan-T cell alloantigens, A.R.T.-1a and A.R.T.-1b, and the fluorescence-activated cell sorter (FACS) to directly enumerate donor- and host-origin thymocytes and T cells in irradiated, histo-compatible recipients. The assay has the advantage over related systems in that it detects more than 95% of total newly-formed thymocytes and T cells at all stages of differentiation; that it is highly sensitive (as few as 1% of the appropriate A.R.T.-1 bearing cells can be detected in cell mixtures); and that it permits selective recovery of donor-and/or host-origin cells for further characterization. The results show that, after a lag period of 10-12 days, the regenerative kinetics of donor-origin thymocytes are linear with respect to time and cell dose, over a range of 2.5 to 50 X 10(6) bone marrow cells. Above a threshold of approximately 400R, the regenerative kinetics of donor-origin thymocytes are independent of irradiation dose, but are inversely related to the age of the recipient. On a per cell basis, bone marrow cells are more efficient than spleen cells at regenerating the thymus. By 4 months after bone marrow cell transfer, permanent chimeras are established in which the proportion of donor-origin T cells approximates that of donor-origin thymocytes, and in which the ratio of presumptive helper (W3/25+) and suppressor/cytotoxic (OX8+) donor-origin T cells is normal. The assay therefore appears to be suitable for following both the purification of prothymocytes from rat hemopoietic tissues and the proliferation and differentiation of their progeny in thymus and peripheral lymphoid tissues.

Animals↗
PubMed1983

Characterization of monoclonal antibodies that define rat T cell alloantigens.

A panel of monoclonal antibodies with specificity for rat T cell alloantigens was prepared by somatic cell hybridization with the use of spleen cells from either BH (ART-1b, 2b) or NBR (ART-1b, 2a) rats immunized with LEW (ART-1a, 2a) thymus, spleen, or lymph node cells. Comparison of the antibodies resulted in three distinct patterns of complement-mediated cytotoxicity. Further comparison of four representative hybridoma antibodies with antisera having specificity for ART antigens by indirect immunofluorescence demonstrated that two of the three patterns corresponded to anti-ART-1a and anti-ART-2a specificities. The patterns of binding of the anti-ART hybridomas were shown to be different from those produced by mouse monoclonal antibodies having anti-leukocyte-common (L-C) or anti-Thy-1.1 activities as well as antibodies produced by the monoclonal W3/25, which detect a subpopulation of T lymphocytes. Functional studies performed in vitro with cells fractionated by treatment with the monoclonal anti-ART antibodies and complement showed the ART-1 determinant recognized by the hybridoma products BC 84A or BY 12.3 is expressed by mature cytolytic T lymphocytes (CTL) and by cells involved in the generation of CTL during MLR, but not plaque-forming cells. Together, the data suggest the antibodies BC 84A and BY 12.3 can be used to define rat T cell populations. To date, the functional significance of cell populations recognized by monoclonal antibodies having anti-ART-2a or anti-ART-3-like activities has not been determined.

Animals↗
PubMed1982

Identification of thymocyte progenitors in hemopoietic tissues of the rat. II. Enrichment of functional prothymocytes on the fluorescence-activated cell sorter.

A quantitative thymocyte regeneration assay was used to monitor the isolation of functional prothymocytes from rat bone marrow on the FACS. Two prothymocyte subpopulations were tentatively identified on the basis of their relative resistance to dexamethasone. Both populations were comprised of undifferentiated, medium-size cells that displayed large amounts of Thy-1 antigen. Simultaneous sorting of bone marrow cells according to relative low angle light scatter (size) and relative fluorescence intensity for Thy-1 resulted in enrichments of 112-fold and 260-fold, respectively, in prothymocyte activity in untreated and dexamethasone-treated bone marrow. These prothymocyte-enriched cell fractions contained or approximately 75% of total functional prothymocyte activity in bone marrow, and represented 1.1 and 0.35% of total untreated and dexamethasone-treated bone marrow cells. Using these enriched cell fractions, significant thymocyte regeneration is possible with as few as 2 X 10(4) and 1 X 10(4) bone marrow cells, respectively. The possible relationship of these functional prothymocyte subpopulations with CFU-S and with TdT-positive cells is discussed.

Animals↗
PubMed1982

Genetic linkage and cell distribution analysis of T cell alloantigens in the rat.

The T cell alloantigens A.R.T.-1, A.R.T.-2, Pta, Ag-F and RT-Ly-2 were examined for linkage to albinism and the haemoglobin variant Hbb, and for cell expression similarities in the rat. The A.R.T.-1 alloantigen was not linked to either A.R.T.-2, albinism or Hbb. The A.R.T.-2 alloantigen was demonstrated to be closely associated to albinism and Hbb with a recombination frequency of approximately 3% with albinism and 1% with Hbb. The four recombinants (out of 104 animals examined) were subsequently analysed with alloantisera to Ag-F, Pta and RT-Ly-2. These alloantisera detected an antigenic system(s) which appeared to co-segregate with A.R.T.-2 in the recombinants studied Characterization of the specific T cell populations expressing each alloantigen demonstrated that removal of the cells bearing any one of the alloantigens removed all the cells expressing any of the other alloantigens. These results demonstrate that the four alloantigenic systems A.R.T.-2, Pta, Ag-F and RT-Ly-2 are located in the same genetic region of linkage group I, and appear to be expressed on the same peripheral T cell subpopulation(s) in the rat.

Animals↗
PubMed1982

Maturation of functional T-lymphocyte subpopulations in the rat.

The T-lymphocyte differentiation alloantigens, A.R.T.-1 and A.R.T.-2 were used to follow the functional development of these cells in the rat. Delayed hypersensitivity and lymphocytes cytotoxic for allogeneic tumor cells were present in adoptively transferred recipients by 3 wk postirradiation and fetal liver reconstitution. However, these animals did not regain appreciable GvH potential until 7.5 wk postreconstitution. Normal percentages of A.R.T-1 lymphocytes were observed at all times in the spleen and lymph nodes of these animals, whereas, below normal numbers of A.R.T-2 lymphocytes were observed up to 7.5 wk postreconstitution. Depletion experiments using specific anti-A.R.T. sera demonstrated that the proliferative response to PHA and the cytotoxic lymphocyte response to alloantigens were reduced after treatment with anti-A.R.T.-1, but not with anti-A.R.T.-2. In contrast, the GvH potential of lymph node cells was reduced by treatment with either anti-A.R.T.-1 or anti-A.R.T.-2 serum plus complement. The use of these A.R.T. alloantisera in the rat has greatly facilitated the establishment of differentiation patterns for functional T lymphocytes and has resulted in the association of specific functional T-cell subpopulations with characteristic surface alloantigens.

Animals↗
PubMed1980

Growth and reproduction complex in the rat. Genes linked to the major histocompatibility complex that affect development.

The linkage of the major histocompatibility complex (MHC) and the growth and reproduction complex (Grc) in the rat was studied in an F2 hybrid population generated from female BIL/1 (RT1l-Grc) and male YO (RT1u-Grc+) animals: 1.722 offspring were born, and 1,568 were weaned and studied. The body weights of the offspring segregated with the RT1 haplotype of the MHC, and the RT1l homozygotes were significantly smaller than their RT1l/u and RT1u/u littermates. The growth rate of the RT1l/l animals was approximately the same as that of the BIL/1 animals, and both were significantly less than the growth rates of the RT1l/u, RT1u/u, and YO (RT1u) animals. The testes of the RT1l animals showed an arrest of spermatogenesis at the early pachytene stage of the primary spermatocytes, and they were approximately 1/10 as heavy as the testes of the RT1l/u and RT1u/u animals. The ovaries in females of all three haplotypes had the same weight, but there was a decrease in the number of ova released per cycle in the RT1 l/l animals. The major loss of the RT1l homozygotes, which caused distortion of the phenotypic ratios among the offspring, did not occur in utero but in the early postnatal period before weaning. There were 7/1568 recombinants between the MHC, using the RT1.A antigen as the marker, and the Grc, using small body size (dw-3) as the marker, and 1/1568 recombinant between the loci influencing body size (dw-3) and fertility (ft) of the Grc. These data gave the following map distances (95% confidence levels): RT1.A to dw-3, 0.45 (0.25-0.96) centimorgans and dw-3 to ft, 0.07 (0.04-0.40) centimorgans. A female recombinant was used develop an inbred line carrying the RT1.Al-Grc+ chromosome.

Animals↗
PubMedDate not supplied

Thymic expression of insulin-related genes in an animal model of autoimmune type 1 diabetes.

BACKGROUND: Insulin and multiple other autoantigens have been implicated in the pathogenesis of autoimmune type 1 diabetes, but the origin of immunological self-reactivity specifically oriented against insulin-secreting islet beta-cells remains obscure. The primary objective of the present study was to investigate the hypothesis that a defect in thymic central T-cell self-tolerance of the insulin hormone family could contribute to the pathophysiology of type 1 diabetes. This hypothesis was investigated in a classic animal model of type 1 diabetes, the Bio-Breeding (BB) rat. METHODS: The expression of the mammalian insulin-related genes (Ins, Igf1 and Igf2) was analysed in the thymus of inbred Wistar Furth rats (WF), diabetes-resistant BB (BBDR) and diabetes-prone BB (BBDP) rats. RESULTS: RT-PCR analyses of total RNA from WF, BBDP and BBDR thymi revealed that Igf1 and Ins mRNAs are present in 15/15 thymi from 2-day-old, 5-day-old and 5-week-old WF, BBDR and BBDP rats. In contrast, a complete absence of Igf2 mRNA was observed in more than 80% of BBDP thymi. The absence of detectable Igf2 transcripts in the thymus of BBDP rats is tissue-specific, since Igf2 mRNAs were detected in all BBDP brains and livers examined. Using a specific immunoradiometric assay, the concentration of thymic IGF-2 protein was significantly lower in BBDP than in BBDR rats (p<0.01). CONCLUSIONS: The present study suggests an association between the emergence of autoimmune diabetes and a defect in Igf2 expression in the thymus of BBDP rats. This tissue-specific defect in gene expression could contribute both to the lymphopenia of these rats (by impaired T-cell development) and the absence of central T-cell self-tolerance of the insulin hormone family (by defective negative selection of self-reactive T-cells).

Aging↗
PubMedDate not supplied

The pathogenesis of autoimmune diabetes mellitus.

There is increasing evidence that both DP and DR BB rats fail to clonally delete autoreactive T cells in the thymus that are important in the development of autoimmune IDDM. The DP BB rat also has a defect in its ability to generate a regulatory (RT6+) T-cell population that would prevent the onset of diabetes and, therefore, it becomes spontaneously diabetic. The DR rat develops autoreactive T cells, but does not express diabetes because of the concurrent development of a regulatory (RT6+) T-cell population. We suggest that in the BB rat, the initial immunological lesion is orchestrated by an APC in close proximity to pancreatic islet beta cells, and may be specifically directed to the beta cell itself. The release of cytokines in the vicinity of the beta cell destroys this highly susceptible target, causing the release of beta cell 'autoantigens'. These autoantigens, in turn, target autoreactive T cells to the beta cells, allowing a focal destructive process to spread throughout the pancreas. The ultimate destruction of the islets and the development of diabetes result from a cascading effect of this process, with the recruitment of other non-specific immune mediators. A similar process may also be initiated by APC within the thyroid of the rat, resulting in thyroiditis. The fact that the thyrocyte does not die is unexplained, but it could relate to the relative insensitivity of this cell type to various cytokines.

Animals↗
PubMedDate not supplied

Induction of immunological tolerance to islet allografts.

T-cell dependent activation of resting B cells involves the interaction of gp39 on T cells with its receptor, CD40, on B cells. We administered either a combination of T-cell-depleted splenic lymphocytes and anti-gp39 monoclonal antibody or antibody alone to establish islet allografts in mice without continuous immunosuppression. Fully allogeneic H-2q FVB islets were permanently accepted by chemically diabetic H-2b C57BL/6 mice provided that the recipients were pretreated with both T-cell-depleted donor spleen cells and anti-gp39 antibody. Antibody alone was less effective in prolonging allograft survival, but we did observe that anti-gp39 mAb alone can exert an independent, primary effect on islet allograft survival that was dose dependent. Targeting gp39, in combination with lymphocyte transfusion, might prove suitable for tolerance induction and allotransplantation without immunosuppression.

Animals↗
PubMedDate not supplied

Blockade of CD40-CD154 interferes with human T cell engraftment in scid mice.

Antibodies to the ligand for CD40 (CD154) have been shown to exert profound effects on the development of cell-mediated immune responses in mice. The present study shows that an antibody to human CD154 (hCD40L) inhibits in vivo Tetanus toxoid (TT) specific secondary antibody responses in hu-PBL-scid mice, as well as the expansion of xenoreactive human T cells in the scid mice. A possible cause for the reduced expansion of xenoreactive, human T cells, was the decreased expression of murine B7.1 and B7.2 caused by the administration of anti-hCD40L. Therefore, it may be that defective maturation of murine antigen-presenting cells impeded the priming and expansion of human xenoreactive T cells.

Adult↗
PubMedDate not supplied

HIV-1 infectivity of human T cells in a human/murine chimeric fetal thymic organ culture system.

Human cord blood (HuCB) can colonize a murine fetal thymus organ culture (FTOC) and generate phenotypically immature (CD4+ CD8+) and mature (CD4+ CD8-; CD4- CD8+) T cells. We have used this model system to demonstrate that the human T cells that develop in this culture system can be infected with HIV-1. A cytopathic and non-cytopathic patient isolate of HIV-1 were used to infect FTOC established using C.B-17 or NOD/LtSz.scid/scid strain fetal thymic lobes colonized with HuCB. At 13-15 days after infection, FTOC were placed in co-culture with human PHA-blasts. These co-cultures demonstrated the presence of replicating HIV-1. Few human CD45+ cells were detectable in the thymic lobes that were infected with HIV-1, while high numbers of human CD45+ T cells were present in the uninfected cultures. These results demonstrate the cytopathicity of HIV-1 on human T lymphocytes that have developed in a HuCB colonized FTOC system.

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