A second subunit of CD8 is expressed in human T cells.

Norment, Anne M.; Littman, Dan R.

doi:10.1002/j.1460-2075.1988.tb03217.x

Cited by 144 publications

(78 citation statements)

References 39 publications

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“…6A, virtually all CD3 ϩ CD8 ϩ CD5 ϩ and CD3 ϩ CD8 ϩ CD5 Ϫ lymphocytes stained with an anti-CD8␣ mAb, whereas an anti-CD8 mAb recognizing a CD8 epitope generated by coupling of the ␣-and ␤-chains recognized all CD3 ϩ CD8 ϩ CD5 ϩ cells, but only a fraction of CD3 ϩ CD8 ϩ CD5 Ϫ lymphocytes. As a consequence, we could conclude that a significantly higher ( p Ͻ 0.01) proportion of CD3 ϩ CD8 ϩ CD5 Ϫ cells expressed the ␣␣ form of the CD8 molecule compared with the CD5 ϩ counterpart, which, as expected (38,43,44), mostly expressed the ␣␤ variant of this coreceptor (Fig. 6B).…”

Section: Phenotypic Characterization Of Cd3supporting

confidence: 63%

“…It is known that the CD8 Ag may be expressed on the cell surface in two molecular forms, as a homodimer composed of two ␣-chains or as a heterodimer composed of an ␣-and a ␤-chain (43,44); the CD8␣␤-expressing population is much more represented in the circulation (38,43,44). To evaluate the expression of these two CD8 forms at the surface of CD3 ϩ CD8 ϩ CD5 Ϫ lymphocytes and in view of the absence of an anti-CD8 mAb specifically directed against the CD8␤ chain, we were forced to calculate the proportion of CD8␣␣-expressing cells as the difference between the figures obtained with two mAb recognizing different epitopes of the CD8 molecule.…”

Section: Phenotypic Characterization Of Cd3mentioning

confidence: 99%

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CD8+αβ+ T Cells That Lack Surface CD5 Antigen Expression Are a Major Lymphotactin (XCL1) Source in Peripheral Blood Lymphocytes

Stievano

Tosello

Marcato

et al. 2003

The Journal of Immunology

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To better characterize the cellular source of lymphotactin (XCL1), we compared XCL1 expression in different lymphocyte subsets by real-time PCR. XCL1 was constitutively expressed in both PBMC and CD4+ cells, but its expression was almost 2 log higher in CD8+ cells. In vitro activation was associated with a substantial increase in XCL1 expression in both PBMC and CD8+ cells, but not in CD4+ lymphocytes. The preferential expression of XCL1 in CD8+ cells was confirmed by measuring XCL1 production in culture supernatants, and a good correlation was found between figures obtained by real-time PCR and XCL1 contents. XCL1 expression was mostly confined to a CD3+CD8+ subset not expressing CD5, where XCL1 expression equaled that shown by γδ+ T cells. Compared with the CD5+ counterpart, CD3+CD8+CD5− cells, which did not express CD5 following in vitro activation, showed preferential expression of the αα form of CD8 and a lower expression of molecules associated with a noncommitted/naive phenotype, such as CD62L. CD3+CD8+CD5− cells also expressed higher levels of the XCL1 receptor; in addition, although not differing from CD3+CD8+CD5+ cells in terms of the expression of most α- and β-chemokines, they showed higher expression of CCL3/macrophage inflammatory protein-1α. These data show that TCR αβ-expressing lymphocytes that lack CD5 expression are a major XCL1 source, and that the contribution to its synthesis by different TCR αβ-expressing T cell subsets, namely CD4+ lymphocytes, is negligible. In addition, they point to the CD3+CD8+CD5− population as a particular T cell subset within the CD8+ compartment, whose functional properties deserve further attention.

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Section: Phenotypic Characterization Of Cd3supporting

confidence: 63%

Section: Phenotypic Characterization Of Cd3mentioning

confidence: 99%

CD8+αβ+ T Cells That Lack Surface CD5 Antigen Expression Are a Major Lymphotactin (XCL1) Source in Peripheral Blood Lymphocytes

Stievano

Tosello

Marcato

et al. 2003

The Journal of Immunology

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“…Although the DP phenotype can be induced in both CD4 and CD8 single-positive T cells, DP T cells with CD8␣␣ subunit are likely to derive from CD4 + T cells, since CD8 + T cells have the ␣␤ subunit. [7][8][9] In fact, mature CD4 + T cells were shown to become DP by stimulation with IL-4 and to have CD4 + CD8␣␣dim phenotype, 10,11 identical to the phenotype of DP LGLL cells. In addition, in our as well as Tonutti's cases, a significant proportion of the residual T cells other than DP T cells showed CD4 + , CD8 − phenotype, which also showed CD11b + , 56 + , 57 + phenotype expressed on the DP cells.…”

Section: Tablementioning

confidence: 99%

“…[7][8][9] Thymic DP T cells and peripheral CD8 single-positive T cells Correspondence: M Mizuki, Department of Hematology and Oncology, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565, Japan; Fax: 81 6 879 3879 Received 1 July 1997; accepted 2 January 1998 express CD8␣␤, while CD4 single-positive T cells become DP on activation with IL-4, and the DP T cells express CD8 of ␣␣ type. 10,11 Intestinal epithelial lymphocytes (IEL) are a distinct T cell subset, which preferentially express CD8␣␣ and contain a DP population.…”

Section: Introductionmentioning

confidence: 99%

Phenotypical heterogeneity of CD4+CD8+ double-positive chronic T lymphoid leukemia

et al. 1998

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Chronic T lymphoid leukemias are defined as leukemias of post-thymic T cells. The CD4 ؉ CD8 ؉ double-positive (DP) phenotype is seen in a few cases. Since DP generally occurs in thymic T cells, whether the DP T leukemia cells represent thymic or peripheral T cells has been a matter of controversy. To address this issue, we studied phenotypical features in eight cases of DP T cell leukemia. Thymic DP T cells and peripheral CD8 ؉ T cells have CD8 of ␣␤ subunit, while CD8␣␣ is induced in CD4 ؉ T cells on activation with IL-4. We found that two patients with DP T large granular lymphocyte leukemia (LGLL) showed dim expression of CD8␣␣, identical to the phenotype on IL-4-activated DP-T cells. The leukemic cells of these patients expressed IL-4 mRNA and produced high levels of IL-4. These findings suggest that they may be derived from peripheral CD4 ؉ T cells. Three patients with adult T cell leukemia/lymphoma (ATLL) showed CD8␣␣, suggestive of an activated peripheral T cell origin. One case expressed CD8␣␣ dim and IL-4 mRNA, while the other two cases expressed no IL-4 mRNA and showed CD8␣␣ bright phenotype, features not found in normal T cell populations. Three patients with T-prolymphocytic leukemia (T-PLL) expressed CD8␣␤. The DP phenotype is relatively common in T-PLL, and CD4 + CD8␣␤ + is characteristic of thymic T cells. The DP T-PLL cells did not express TdT,CD1 or recombination activating gene-1 (RAG-1), which is down-regulated at the late stage of thymic T cell development. On the basis of these findings, we propose a late thymic origin for DP T-PLL. The phenotype of DP T cells differed for each entity and appeared to correlate with minor normal DP T cell population.

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“…CD8 is encoded by two distinct genes, termed CD8␣ (or Lyt 2) and CD8␤ (or Lyt 3) and expressed on the cell surface as a mixture of disulfide-linked CD8␣␣ homodimers and CD8␣␤ heterodimers (2)(3)(4)(5)(6)(7). CD8␣ is a 34 -37-kDa transmembrane glycoprotein whose extracellular segment contains a compact 122-amino acid (aa) N-terminal Ig-like domain and an extended 48-residue stalk region.…”

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confidence: 99%

Expression, Purification, and Functional Analysis of Murine Ectodomain Fragments of CD8αα and CD8αβ Dimers

Kern¹,

Hussey

Spoerl

et al. 1999

Journal of Biological Chemistry

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Soluble mouse CD8␣␣ and CD8␣␤ dimers corresponding to the paired ectodomains (CD8 f ) or their respective component Ig-like domains (CD8) were expressed in Chinese hamster ovary cells or the glycosylation variant Lec3.2.8.1 cells as secreted proteins using a leucine zipper strategy. The affinity of CD8␣␣ f for H-2K b as measured by BIAcore revealed a ϳ65 M K d , similar to that of CD8␣␤ f . Consistent with this result, CD8␣␣ f as well as CD8␣␤ f blocked the effector function of N15 T cell receptor transgenic cytolytic T cells in a comparable, dose-dependent fashion. Furthermore, both Lec3.2.8.1-produced and Chinese hamster ovary-produced CD8 homodimers and heterodimers were active in the inhibition assay. These results suggest that the Ig-like domains of CD8 molecules are themselves sufficient to block the requisite transmembrane CD8-pMHC interaction between cytolytic T lymphocytes and target cells. Moreover, given the similarities in co-receptor affinities for pMHC, the findings suggest that the greater efficiency of CD8␣␤ versus CD8␣␣ co-receptor function on T cells is linked to differences within their membranebound stalk regions and/or intracellular segments. As recently shown for sCD8␣␣, the yield, purity and homogeneity of the deglycosylated protein resulting from this expression system is sufficient for crystallization and x-ray diffraction at atomic resolution.CD8 has been shown to function in mediating signal transduction and adhesion on a subset of cells within the T cell compartment and is critically involved in the development of T cells expressing MHC class I-restricted T cell receptor (TCR) 1 (1). CD8 is encoded by two distinct genes, termed CD8␣ (or Lyt 2) and CD8␤ (or Lyt 3) and expressed on the cell surface as a mixture of disulfide-linked CD8␣␣ homodimers and CD8␣␤ heterodimers (2-7). CD8␣ is a 34 -37-kDa transmembrane glycoprotein whose extracellular segment contains a compact 122-amino acid (aa) N-terminal Ig-like domain and an extended 48-residue stalk region. A 28-aa cytoplasmic domain, including a cysteine motif responsible for interaction with p56 lck , follows a canonical hydrophobic transmembrane anchor. CD8␤ is a 32-kDa glycoprotein sharing a similar architecture as CD8␣ but with Ͻ20% sequence identity (4, 5). The stalk regions of the CD8␣ and ␤ chains are quite different in length, with the CD8␤ stalk being 10 -13 residues shorter than that of CD8␣. Interestingly, the sialic acid content of O-linked glycans adducted to CD8␤ selectively decreases on thymocytes and activated T cells compared with that found on resting T cells. For its cell surface expression, CD8␤ requires association with the CD8␣ subunit, forming a CD8␣␤ heterodimer (6, 8). Moreover, CD8 genes are selectively expressed. Although CD8␣␤ heterodimers are predominantly found on the surface of TCR␣␤ T cells and thymocytes, CD8␣␣ homodimers are additionally expressed on a subset of ␥␦ T cells, intestinal intraepithelial lymphocytes and natural killer cells (9, 10). Hence, it is safe to conclude that the two sets of CD8 co-r...

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A second subunit of CD8 is expressed in human T cells.

Cited by 144 publications

References 39 publications

CD8+αβ+ T Cells That Lack Surface CD5 Antigen Expression Are a Major Lymphotactin (XCL1) Source in Peripheral Blood Lymphocytes

CD8+αβ+ T Cells That Lack Surface CD5 Antigen Expression Are a Major Lymphotactin (XCL1) Source in Peripheral Blood Lymphocytes

Phenotypical heterogeneity of CD4+CD8+ double-positive chronic T lymphoid leukemia

Expression, Purification, and Functional Analysis of Murine Ectodomain Fragments of CD8αα and CD8αβ Dimers

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