The Experts below are selected from a list of 69 Experts worldwide ranked by ideXlab platform
Bondada Subbarao - One of the best experts on this subject based on the ideXlab platform.
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physiology of murine b lymphocytes ii life spans of mitogen and Thymus Independent Antigen type 2 reactive b lymphocytes from aged mice
Mechanisms of Ageing and Development, 1991Co-Authors: Venkatachalam Udhayakumar, Niranjan S Goud, Richard J Cross, Bondada SubbaraoAbstract:Abstract We showed earlier that life spans of murine B lymphocytes could be estimated by measuring the functional reactivities of normal B cells upon transfer into x-linked immunodeficient (xid) mice, which do not respond to anti-mouse IgM (anti-μ) antibodies and thymic-Independent type -2 (TI-2) Antigens. Here the same approach was adopted, to evaluate the life spans of B-lymphocytes from aged mice. Spleen cells from normal young and aged mice were transferred into young or aged xid recipients and the decay kinetics were followed by measuring the proliferative response to anti-μ and PFC response to TNP-Ficoll, a prototype TI-2 Antigen. The results indicated that anti-μ reactive B cells of both young and aged mice decayed with similar non-linear kinetics. About 50% of the donor cells decayed in 8–10 days, whereas, the remaining decayed at a slower rate and it appeared that the median life-expectancy of this latter population could be at least 3 weeks. Essentially, there was no apparent difference in the decay kinetics of anti-μ reactive B cells of young and aged mice. Unlike anti-μ reactive cells, TNP-Ficoll reactive B cells showed 2–3-fold enhancement in the PFC response during the first 2 weeks, and persisted at least until 5 weeks post transfer. This result indicated that TNP-Ficoll reactive B cells are long-lived. Further, it was found that the turn over rate of TNP-Ficoll reactive B
David W. Scott - One of the best experts on this subject based on the ideXlab platform.
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Effect of priming with a Thymus-Independent Antigen on susceptibility to B-cell tolerance.
Cellular immunology, 1992Co-Authors: Xiao-rui Yao, David W. ScottAbstract:The effects of priming on the susceptibility of B-cell subsets to tolerance induction have been tested in a model system in which anti-immunoglobulin (anti-Ig) has been employed as a surrogate for tolerogen. T-cell-depleted B cells were primed in vitro with fluorescein or trinitrophenylated Ficoll (a Thymus-Independent (TI) Antigen) and then exposed overnight to anti-Ig to attempt to induce B-cell anergy. Primed cells were relatively resistant to this tolerance protocol and resistance was hapten specific. The dose response and kinetics suggested that this process was not due to receptor blockade or modulation, but was an active process. Moreover, this priming for resistance to tolerance was reproduced in vivo upon intraperitoneal treatment with haptenated Ficoll. Such in vivo priming for tolerance resistance was long-lasting and did not occur with a Thymus-dependent priming protocol with fluoresceinated hemocyanin. These results are discussed in terms of TI priming to drive B cells into cycle and express novel functional and phenotypic properties.
Venkatachalam Udhayakumar - One of the best experts on this subject based on the ideXlab platform.
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physiology of murine b lymphocytes ii life spans of mitogen and Thymus Independent Antigen type 2 reactive b lymphocytes from aged mice
Mechanisms of Ageing and Development, 1991Co-Authors: Venkatachalam Udhayakumar, Niranjan S Goud, Richard J Cross, Bondada SubbaraoAbstract:Abstract We showed earlier that life spans of murine B lymphocytes could be estimated by measuring the functional reactivities of normal B cells upon transfer into x-linked immunodeficient (xid) mice, which do not respond to anti-mouse IgM (anti-μ) antibodies and thymic-Independent type -2 (TI-2) Antigens. Here the same approach was adopted, to evaluate the life spans of B-lymphocytes from aged mice. Spleen cells from normal young and aged mice were transferred into young or aged xid recipients and the decay kinetics were followed by measuring the proliferative response to anti-μ and PFC response to TNP-Ficoll, a prototype TI-2 Antigen. The results indicated that anti-μ reactive B cells of both young and aged mice decayed with similar non-linear kinetics. About 50% of the donor cells decayed in 8–10 days, whereas, the remaining decayed at a slower rate and it appeared that the median life-expectancy of this latter population could be at least 3 weeks. Essentially, there was no apparent difference in the decay kinetics of anti-μ reactive B cells of young and aged mice. Unlike anti-μ reactive cells, TNP-Ficoll reactive B cells showed 2–3-fold enhancement in the PFC response during the first 2 weeks, and persisted at least until 5 weeks post transfer. This result indicated that TNP-Ficoll reactive B cells are long-lived. Further, it was found that the turn over rate of TNP-Ficoll reactive B
Edna Mozes - One of the best experts on this subject based on the ideXlab platform.
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ia Antigen t cell interactions for a Thymus Independent Antigen composed of d amino acids
Proceedings of the National Academy of Sciences of the United States of America, 1993Co-Authors: Einat Zisman, Molly Dayan, Michael Sela, Edna MozesAbstract:Abstract Synthetic polypeptide Antigens of L amino acids, although bearing repeating sequences, are Thymus-dependent (L-TD), whereas the same polymers composed of D amino acids are Thymus-Independent (D-TI), probably due to a slower rate of metabolism. Yet we found that lymph-node cells of BALB/c mice immunized with D-TI proliferate in response to it in vitro. To follow T-cell activation by D-TI, we established T-cell hybridomas to D-TI and to its analog composed of L isomers, L-TD, for comparison. The T-cell hybridomas express membrane alpha/beta T-cell receptors and secrete interleukin 2 upon stimulation with the respective Antigen. In addition, D-TI-specific hybridomas are stimulated, to a lesser extent, by the L-TD Antigen, whereas only some L-TD-specific hybridomas recognize D-TI. Moreover, biotinylated analogs of D-TI and L-TD bind to splenic Antigen-presenting cells (APCs) from BALB/c mice. Binding is inhibited by an excess of nonbiotinylated L-TD, and by an excess of a peptide comprising residues 259-271 of the human acetylcholine receptor alpha subunit, which binds to I-Ad and I-Ed molecules without prior processing. Analysis of APC lysates following incubation of the APCs with biotinylated D-TI and L-TD reveals that the biotinylated Antigen moiety is associated with Ia molecules. D-TI and L-TD bind to Ia molecules on intact APCs with similar KD values, 5 x 10(-8) M and 3 x 10(-8) M, respectively. However, D-TI has faster kinetics of binding than L-TD, probably due to different processing requirements. Hence, we have demonstrated a major histocompatibility complex class II-mediated T-cell response to a Thymus-Independent Antigen.
C. Fernandez - One of the best experts on this subject based on the ideXlab platform.
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Understanding Thymus-Independent Antigen-induced reduction of Thymus-dependent immune responses
Immunology, 2004Co-Authors: Karin Lindroth, Elena Fernández Mastache, Izaura M. Roos, África González Fernández, C. FernandezAbstract:Deficiencies in immune responses against polysaccharides can have direct consequences for patients, and therefore, a better understanding of these immune reactions is crucial. We have studied the immune response against the polysaccharide dextran B512 (Dx). Administration of immunogenic doses of Thymus-Independent (TI) Dx reduces the immunoglobulin G1 response to later challenges with a Thymus-dependent (TD) form of Dx. We investigated if this suppression is a general phenomenon caused not only by Dx but also by other TI Antigens, and examined possible mechanisms contributing to this unresponsiveness. We show that clonal exhaustion is not involved in modulating subsequent responses, nor is signalling via FcγRIIB or other antibody mediated pathways. The reduced TD response is not an exclusive Dx phenomenon; it is also induced by TI Antigen oxazolone (Ox). However, responses against the hapten dinitrophenyl (DNP) are not affected, indicating that the TI priming negative effect is not a general process. This may be explained by the restricted immune response to both Dx and Ox, in contrast to the unrestricted DNP response. Our conclusion from these experiments is that the underlying mechanism for the TI-induced reduction of latter TD responses is a property of the TI activation itself.