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A T cell receptor-specific blockade of positive selection.

Baldwin KK, Reay PA, Wu L, Farr A, Davis MM - J. Exp. Med. (1999)

Bottom Line: One of these antibodies (G35) specifically blocks the positive selection of transgenic thymocytes expressing a T cell receptor that is reactive to this peptide- MHC complex.Furthermore, G35 does not block the differentiation of transgenic T cells bearing receptors for a different I-Ek-peptide complex.This antibody recognizes a subset of endogenous I-Ek-peptide complexes found on a significant fraction of thymic antigen-presenting cells, including cortical and medullary epithelial cells.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, and the Department of Microbiology and Immunology, Stanford University, Stanford, California 94305, USA.

ABSTRACT
To investigate the influence of endogenous peptides on the developmental processes that occur during thymocyte selection, we have used monoclonal antibodies that preferentially recognize the major histocompatibility complex (MHC) molecule I-Ek when it is bound to the moth cytochrome c peptide (88-103). One of these antibodies (G35) specifically blocks the positive selection of transgenic thymocytes expressing a T cell receptor that is reactive to this peptide- MHC complex. Furthermore, G35 does not block the differentiation of transgenic T cells bearing receptors for a different I-Ek-peptide complex. This antibody recognizes a subset of endogenous I-Ek-peptide complexes found on a significant fraction of thymic antigen-presenting cells, including cortical and medullary epithelial cells. The sensitivity of G35 to minor alterations in peptide sequence suggests that the thymic peptide-MHC complexes that mediate the positive selection of a particular class II MHC-restricted thymocyte are structurally related to the complexes that can activate it in the periphery.

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Related in: MedlinePlus

G35 blocks 5C.C7 transgenic T cell differentiation in vitro.  Analysis of CD4/8 expression on thymocytes removed from stromal cell  cultures derived from B10.Br (top) or C57BL/6 (bottom) mice after 26 (a  and d) or 52 h (b, c, e, and f). G35 was added to a final concentration of  50 μg/ml in c and f. Numbers on plots refer to the percent of total live  transgenic thymocytes that fall within each boxed population.
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Figure 3: G35 blocks 5C.C7 transgenic T cell differentiation in vitro. Analysis of CD4/8 expression on thymocytes removed from stromal cell cultures derived from B10.Br (top) or C57BL/6 (bottom) mice after 26 (a and d) or 52 h (b, c, e, and f). G35 was added to a final concentration of 50 μg/ml in c and f. Numbers on plots refer to the percent of total live transgenic thymocytes that fall within each boxed population.

Mentions: Thymic epithelial cells were isolated from thymuses taken from 3–4-wk-old mice and grown in media that selectively kills fibroblast-derived cells to enrich for thymic stromal epithelial cells (32). To provide unmanipulated immature CD4+8+ cells bearing the 5C.C7 receptor, TCR transgenic mice were crossed to a nonselecting background (C57BL/6). The majority of the immature thymocytes from these mice are immature CD4+8+CD69− TCRlow/intermediate cells that fail to initiate CD8 downregulation even after 52 h in culture (Baldwin, K.K., unpublished data and reference 33). In contrast, when these immature thymocytes are cocultured with thymic stromal cells that express I-Ek, they begin to downregulate CD8 after 26 h (Fig. 3, a and d). After 52 h, the thymocytes still attached to the I-Ek–positive stromal cells are almost entirely mature CD4+8− cells (Fig. 3, b and e). Additional FACS® analyses show that these cells express the high levels of CD69 and low levels of HSA that are characteristic of differentiated CD4+8− thymocytes (Baldwin, K.K., unpublished data).


A T cell receptor-specific blockade of positive selection.

Baldwin KK, Reay PA, Wu L, Farr A, Davis MM - J. Exp. Med. (1999)

G35 blocks 5C.C7 transgenic T cell differentiation in vitro.  Analysis of CD4/8 expression on thymocytes removed from stromal cell  cultures derived from B10.Br (top) or C57BL/6 (bottom) mice after 26 (a  and d) or 52 h (b, c, e, and f). G35 was added to a final concentration of  50 μg/ml in c and f. Numbers on plots refer to the percent of total live  transgenic thymocytes that fall within each boxed population.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1887687&req=5

Figure 3: G35 blocks 5C.C7 transgenic T cell differentiation in vitro. Analysis of CD4/8 expression on thymocytes removed from stromal cell cultures derived from B10.Br (top) or C57BL/6 (bottom) mice after 26 (a and d) or 52 h (b, c, e, and f). G35 was added to a final concentration of 50 μg/ml in c and f. Numbers on plots refer to the percent of total live transgenic thymocytes that fall within each boxed population.
Mentions: Thymic epithelial cells were isolated from thymuses taken from 3–4-wk-old mice and grown in media that selectively kills fibroblast-derived cells to enrich for thymic stromal epithelial cells (32). To provide unmanipulated immature CD4+8+ cells bearing the 5C.C7 receptor, TCR transgenic mice were crossed to a nonselecting background (C57BL/6). The majority of the immature thymocytes from these mice are immature CD4+8+CD69− TCRlow/intermediate cells that fail to initiate CD8 downregulation even after 52 h in culture (Baldwin, K.K., unpublished data and reference 33). In contrast, when these immature thymocytes are cocultured with thymic stromal cells that express I-Ek, they begin to downregulate CD8 after 26 h (Fig. 3, a and d). After 52 h, the thymocytes still attached to the I-Ek–positive stromal cells are almost entirely mature CD4+8− cells (Fig. 3, b and e). Additional FACS® analyses show that these cells express the high levels of CD69 and low levels of HSA that are characteristic of differentiated CD4+8− thymocytes (Baldwin, K.K., unpublished data).

Bottom Line: One of these antibodies (G35) specifically blocks the positive selection of transgenic thymocytes expressing a T cell receptor that is reactive to this peptide- MHC complex.Furthermore, G35 does not block the differentiation of transgenic T cells bearing receptors for a different I-Ek-peptide complex.This antibody recognizes a subset of endogenous I-Ek-peptide complexes found on a significant fraction of thymic antigen-presenting cells, including cortical and medullary epithelial cells.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, and the Department of Microbiology and Immunology, Stanford University, Stanford, California 94305, USA.

ABSTRACT
To investigate the influence of endogenous peptides on the developmental processes that occur during thymocyte selection, we have used monoclonal antibodies that preferentially recognize the major histocompatibility complex (MHC) molecule I-Ek when it is bound to the moth cytochrome c peptide (88-103). One of these antibodies (G35) specifically blocks the positive selection of transgenic thymocytes expressing a T cell receptor that is reactive to this peptide- MHC complex. Furthermore, G35 does not block the differentiation of transgenic T cells bearing receptors for a different I-Ek-peptide complex. This antibody recognizes a subset of endogenous I-Ek-peptide complexes found on a significant fraction of thymic antigen-presenting cells, including cortical and medullary epithelial cells. The sensitivity of G35 to minor alterations in peptide sequence suggests that the thymic peptide-MHC complexes that mediate the positive selection of a particular class II MHC-restricted thymocyte are structurally related to the complexes that can activate it in the periphery.

Show MeSH
Related in: MedlinePlus