In rats expressing the f allele of the rat MHC (RT1f), CD8 T cells utilizing the V alpha 8.2 segment are 10-fold overselected during thymic development, resulting in V alpha 8.2 expression by 14% of ...mature CD8 T cells as compared to 1-2% in MHC congenic strains. In the alloreactive responses of CD8 T cells from RT1f-negative rats against RT1f, V alpha 8.2+ CD8 T cells are also preferentially expanded. Neither overselection nor alloreactivity of V alpha 8.2+ TCR require selective V beta pairing. However, RT1f alloreactive V alpha 8.2+ TCR preferentially use a related set of J alpha segments which contribute short homogeneous CDR3 alpha loops, with features suggesting peptide promiscuity, and little N additions. In contrast, only few overselected V alpha 8.2+ CD8 T cells showed an imprint of positive selection on J usage or CDR3 composition. The results demonstrate that a single V alpha segment can promote both MHC allele-specific positive selection and alloreactivity, and that the latter is more dependent on an additional contribution of CDR3 alpha, possibly by promoting reactivity with a diverse set of MHC-bound peptides or by providing additional MHC contacts.
Functionally defined clones and lines of murine lymphocytes including myelomas, helper, suppressor and cytolytic T lymphocytes were analyzed for their glycosphingolipids (GSLs). GSLs were ...characterized by thin-layer chromatography and by high-performance liquid chromatography. Lymphocytes with different functions displayed, besides a number of common GSLs, some characteristic GSLs that may be regarded as markers. Globotriaosylceramide was found on myelomas and B blasts, whereas globotetraosylceramide was confined to helper T cells. All T cells including cytolytic T lymphocytes displayed gangliotetraosylceramide (asialo-GM1) as a major GSL, which was further characterized by sequential degradation with exoglycosidases.
Taking the thymus to pieces Kyewski, B; Hünig, T
Immunology today (Amsterdam. Regular ed.),
08/1992, Letnik:
13, Številka:
8
Journal Article
Complex in vitro and in vivo techniques are being combined to unlock the remaining secrets of the thymus. In this report from a recent thymus workshop*, Bruno Kyewski and Thomas Hünig describe the ...genetic manipulations aimed at clarifying the mechanisms of T-cell selection and lineage commitment, and the use of organ culture and immunohistology to identify the thymic microenvironments in which these events take place.
The relationship between alpha/beta and gamma/delta T-cell lineages was studied in rats using RT-PCR analysis of TCRbeta transcripts in gamma/delta T-cell hybridomas and an intracellular staining ...technique to detect TCRbeta protein in primary gamma/delta T-cells. We report the presence of functional TCRbeta transcripts in 2/9 gamma/delta T-cell hybridomas. About 15% of peripheral gamma/delta T-cells and thymocytes also express TCRbeta protein, giving a minimum estimate for successful Tcrb rearrangement based on ex vivo single cell analysis. In athymic rats, gamma/delta T-cells expressing intracellular beta protein are present but at a lower frequency than in euthymic controls, suggesting that in the thymus, more gamma/delta T-cell precursors pass through a stage where functional beta rearrangement has occurred than in extrathymic sites. Analysis of TCR expression in purified transitory immature CD4-8+ (iCD8SP) thymocytes and their spontaneously developing CD4+8+ (DP) progeny showed that TCRy mRNA is expressed in iCD8SP cells but not in their immediate DP progeny that reinitiate RAG-I transcription and commence alpha/betaTCR expression. We conclude that rat gamma/delta T cells can separate from the alpha/beta lineage after TCRbeta expression, but not after entry into the DP compartment.
Objective. To investigate the role of γ/δ T cells in Mycobacterium tuberculosis–induced rat adjuvant arthritis.
Methods. Rats with adjuvant arthritis were injected with the anti–T cell receptor γ/δ ...(anti‐TCR γ/δ) monoclonal antibody V65 according to a preventive protocol, a pre–arthritis peak protocol, and a late therapeutic protocol. Arthritis severity and joint destruction were monitored, and depletion of target cells was analyzed by flow cytometry.
Results. Although all protocols led to successful depletion of TCRγ/δbright cells in peripheral blood and lymph nodes, none of the regimens influenced clinical parameters of adjuvant arthritis. If rats were treated before the clinical peak of adjuvant arthritis, however, joint destruction was significantly more severe than in vehicle‐treated rats.
Conclusion. Rat adjuvant arthritis is not promoted or perpetuated by γ/δ T cells. Aggravation of joint destruction with pre–arthritis peak anti‐γ/δ treatment suggests a stage‐dependent protective role of γ/δ T cells in adjuvant arthritis.
Lewis rats experimentally infected with
Yersinia enterocolitica develop sterile arthritis similar to
Yersinia-associated reactive arthritis in humans. To investigate the putative role of αβ T cells ...in the pathogenesis of
Yersinia-induced arthritis (YIA) rats were treated with the monoclonal antibody (mAb) R73 mAb directed against the rat αβ T cell receptor. In spite of reduction of αβ T cells in peripheral blood and in liver lesions of
Yersinia-infected rats this serotherapy had no suppressive effect on YIA. Moreover, R73 mAb treatment had no influence on the number of αβ T cells in the inflammed synovial tissue. In contrast, R73 mAb serotherapy in
Mycobaterium tuberculosis-immunized rats blocked development of adjuvant arthritis (AA) and suppressed the presence of αβ T cells in the synovial tissue. These results suggest fundamental differences between the immunopatho-mechanism of YIA caused by bacterial infection and AA induced by bacterial immunization and known to be T cell mediated. These data might have consequences for putative serotherapy of arthritis in humans.
We have constructed bone marrow irradiation chimeras to investigate the influence of self antigens on the specificity of the T lymphocyte receptor repertoire. Bone marrow cells from (A × B)F1mice ...heterozygous for the major histocompatibility genes were allowed to mature into T cells in irradiated parent A or parent B strains. More than 8 weeks after irradiation, when the lymphoid system had regenerated from the F1stem cells, the degree of T cell reactivity to mutant major histocompatibility antigens, A′, was assessed. It was found that T cells that had matured in the irradiated A mice, F1→ A chimeras, responded better to A′antigen than did T cells from the F1→ B chimeras. Because the mutant histocompatibility antigen A′is very similar in structure to A, differing only by one or a few residues, this suggests that the T cell repertoire in F1→ parent chimeras reacts preferentially with foreign antigens that are slight variants of the self antigens expressed on radiation-resistant cells--probably cells in the thymus.
In this paper, we present the design, development, and characteristics of the novel aerosol mass spectrometer ERICA (ERC Instrument
for Chemical composition of Aerosols; ERC – European Research ...Council) and
selected results from the first airborne field deployment. The instrument
combines two well-established methods of real-time in situ measurements of
fine particle chemical composition. The first method is the laser desorption and ionization technique, or laser ablation technique, for single-particle mass spectrometry (here with a frequency-quadrupled Nd:YAG laser at λ = 266 nm). The second method is a combination of thermal particle
desorption, also called flash vaporization, and electron impact ionization
(like the Aerodyne aerosol mass spectrometer). The same aerosol sample flow
is analyzed using both methods simultaneously, each using time-of-flight
mass spectrometry. By means of the laser ablation, single particles are
qualitatively analyzed (including the refractory components), while the flash vaporization and electron impact ionization technique provides quantitative information on the non-refractory components (i.e., particulate sulfate, nitrate, ammonia, organics, and chloride) of small particle ensembles. These
techniques are implemented in two consecutive instrument stages within a
common sample inlet and a common vacuum chamber. At its front end, the
sample air containing the aerosol particles is continuously injected via an
aerodynamic lens. All particles which are not ablated by the Nd:YAG laser in the first instrument stage continue their flight until they reach the second instrument stage and impact on the vaporizer surface (operated at 600 ∘C). The ERICA is capable of detecting single particles with
vacuum aerodynamic diameters (dva) between ∼ 180 and 3170 nm (d50 cutoff). The chemical characterization of single particles is achieved by recording cations and anions with a bipolar time-of-flight mass spectrometer. For the measurement of non-refractory components, the particle size range extends from approximately 120 to 3500 nm (d50 cutoff; dva), and the cations are detected with a time-of-flight mass
spectrometer. The compact dimensions of the instrument are such that the
ERICA can be deployed on aircraft, at ground stations, or in mobile laboratories.
To characterize the focused detection lasers, the ablation laser, and the
particle beam, comprehensive laboratory experiments were conducted. During
its first deployments the instrument was fully automated and operated during 11 research flights on the Russian high-altitude research aircraft M-55
Geophysica from ground pressure and temperature to 20 km altitude at 55 hPa and
ambient temperatures as low as −86 ∘C. In this paper, we show
that the ERICA is capable of measuring reliably under such conditions.
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