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C Clayberger

Publications and source records attributed to C Clayberger.

At least 91 records · Page 5Linked to original sources
PubMed1988

A human T cell-specific molecule is a member of a new gene family.

We have used a cDNA library enriched for T cell-specific sequences to isolate genes expressed by T cells but not by other cell types. We report here one such gene, designated RANTES, which encodes a novel T cell-specific molecule. The RANTES gene product is predicted to be 10 kDa and, after cleavage of the signal peptide, approximately 8 kDa. Of the 68 residues, 4 are cysteines, and there are no sites for N-linked glycosylation. RANTES is expressed by cultured T cell lines that are Ag specific and growth factor dependent. RANTES expression is inducible in PBL by Ag or mitogen. In CTL, expression of RANTES decreases after stimulation with Ag and growth factors. Interestingly, RANTES was not expressed by any T cell tumor line tested. There is significant homology between the RANTES sequence and several other T cell genes, suggesting that they comprise a previously undescribed family of small T cell molecules.

Amino Acid Sequence↗
PubMed1988

Recombinant gamma interferon increases the binding of peripheral blood mononuclear leukocytes and a Leu-3+ T lymphocyte clone to cultured keratinocytes and to a malignant cutaneous squamous carcinoma cell line that is blocked by antibody against the LFA-1 molecule.

Because keratinocytes (KCs) express HLA-DR in a wide variety of skin diseases in which mononuclear leukocytes are observed in close apposition to KCs (i.e., graft-versus-host disease), and since gamma interferon (IFN-gamma) induces HLA-DR expression on KCs, we asked whether IFN-gamma treatment of KCs would influence the adherence of mononuclear leukocytes. When allogeneic peripheral blood mononuclear leukocytes (PBML) and a Leu-3+ T cell clone were coincubated with IFN-gamma-treated KCs (300 U/ml, 3 days), there was a marked increase in binding compared with nontreated KCs. Similar binding results were obtained using a cutaneous squamous carcinoma cell line (SCL-1) after IFN-gamma treatment. The IFN effect was relatively specific for IFN-gamma, as neither IFN-alpha nor -beta had any effect. Tumor necrosis factor exposure (500 U/ml, 3 days) increased the binding of the Leu-3+ T cell clone to both KCs and SCL-1 cells. Neutrophils displayed a less marked (but statistically significant) increase in binding to IFN-gamma-treated KCs. Using the Leu-3+ cell clone and SCL-1 cells, detailed kinetic analysis of the effect of IFN-gamma on binding was performed. The increased adherence between the cells began to appear after only 7 hours of treatment with r-IFN-gamma (300 U/ml) and reached a plateau at 48 hours, with significantly enhanced binding continuing for at least 48 hours after removal of IFN-gamma. The mechanism of binding was explored by preincubation of the PBML/Leu-3+ T cells with anti-LFA-1 (lymphocyte function-associated antigen) antibody (0.6-6.0 micrograms/ml), which totally inhibited the binding with no effect by anti-LFA-2 or -3 or class I or II antibodies despite documented binding of these antibodies to the cells. These results suggest that, after exposure to IFN-gamma, the ability of KCs to bind mononuclear leukocytes is strongly enhanced, and this adherence may be important in leukocyte trafficking in the skin as well as contributing to altered KC-leukocyte interaction, which may be of fundamental importance in a variety of skin disease.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Absence of cell surface LFA-1 as a mechanism of escape from immunosurveillance.

During studies of T-cell recognition of autologous tumour cells, a number of tumour cell lines derived from patients with lymphoma proved to be poor stimulators of both autologous and allogeneic T-cell responses. Analysis of the tumour cell surface molecules indicated that expression of the lymphocyte-function-associated antigen, LFA-1, was lacking, whereas normal leucocytes from these patients expressed normal levels of LFA-1. Examination of other lymphoid tumours revealed that most high grade lymphomas, but not most low or intermediate grade lymphomas, do not express the LFA-1 molecule. Furthermore, in an initial survey, the tumours from 5 of 7 patients with non-relapsing large cell lymphomas expressed LFA-1 whereas only 3 of 18 patients with relapsing lymphomas had tumours that did so. These findings suggest that tumour cells lacking surface LFA-1 cannot initiate an effective immune response in vivo. This lack of immunogenicity might contribute to escape from immunosurveillance.

Antigens, Surface↗
PubMed1987

In vitro mutagenesis at a single residue introduces B and T cell epitopes into a class I HLA molecule.

We have studied the interaction of HLA class I antigens with alloreactive cytotoxic T lymphocytes and monoclonal antibodies using site-directed mutagenesis and expression of an HLA-Aw68.1 gene. Two mutants containing distinct substitutions at polymorphic residues near the NH2-terminal end of the alpha 2 domain were made. One mutant with substitutions at positions 95 and 97 corresponding to residues found in HLA-A2.1 showed no alterations in binding of HLA-Aw68- or HLA-A2-specific monoclonal antibodies, but was reactive with some HLA-A2-specific CTL clones. A second mutant, in which glycine at position 107 was replaced with tryptophan found at that position in HLA-A2.1, was recognized by HLA-A2-specific CTL clones and HLA-A2, Aw69-specific monoclonal antibodies. Thus, substitution of a single amino acid residue at position 107 of the HLA-Aw68.1 molecule generates an allospecific determinant shared with HLA-A2.1 and recognized by both B and T lymphocytes.

Amino Acid Sequence↗
PubMed1987

Expression of Leu-19 (NKH-1) antigen on IL 2-dependent cytotoxic and non-cytotoxic T cell lines.

The Leu-19 (NKH-1) antigen is expressed on human peripheral blood NK cells and a subset of peripheral blood cytotoxic T lymphocytes that kill "NK-sensitive" tumor cell targets without major histocompatibility complex restriction. In the present study, we demonstrate that the Leu-19 (NKH-1) antigen is also expressed on most interleukin 2 (IL 2) dependent T cell lines and clones that have been maintained in long term culture. The Leu-19 (NKH-1) antigen expressed on an antigen-specific, class I directed cytotoxic T lymphocyte cell line was an approximately 200,000 to 220,000 dalton protein, similar to Leu-19 (NKH-1) protein expressed on natural killer cells and KG1a, an immature stem cell leukemia cell line. Furthermore, Leu-19 (NKH-1) was expressed on both CD4+ and CD8+ IL 2 dependent T cell clones, and was present on both cytotoxic and non-cytotoxic T cell clones. Thus expression of Leu-19 (NKH-1) antigen on cultured cell lines does not directly correlate with cytotoxic function, antigenic specificity, or cell lineage.

Antibodies, Monoclonal↗
PubMed1987

Human allospecific cytolytic T lymphocyte lysis of a murine cell transfected with HLA-A2.

A variety of molecules are involved in the interaction of human allospecific cytolytic T lymphocytes (CTL) with target cells. Monoclonal antibodies specific for these molecules inhibit CTL-target conjugate formation and/or lysis. To further study recognition and lysis of targets by human CTL, we used a murine mastocytoma cell line transfected with the histocompatibility leukocyte antigen (HLA)-A2 gene (P815-A2+) as a target for human HLA-A2-specific CTL. We find that only a subset of human HLA-A2-specific CTL can lyse murine P815-A2+ cells, suggesting that the murine cells may lack one or more accessory molecules needed for CTL recognition and lysis.

Animals↗
PubMed1987

The isolation and sequence of a novel gene from a human functional T cell line.

Using a subtractive hybridization procedure we have constructed a cDNA library enriched for sequences present in functional human T cell lines, but not in human EBV-transformed B cell lines. We have isolated a cDNA clone, AH2-519, representing a novel gene, designated 519. This novel gene is expressed in functional human cytolytic and Th cell lines but not in a variety of other cell lines, including several long-term human T cell tumor lines. The expression of gene 519 is inducible in cultures of normal human PBL using antigenic or mitogenic stimulation. Neither the DNA sequence determined from a full-length cDNA clone overlapping with clone AH2-519 nor the amino acid sequence of its predicted protein product has significant homology to published sequences in the GenBank or NBRF databases. The restricted expression of gene 519 suggests that its gene product is involved in the growth and/or differentiation of normal T cells. The data also show that normal, nontransformed, functional T cells express gene products that can not be readily identified in long-term tumor lines of the same cell lineage.

Amino Acid Sequence↗
PubMed1987

Identification and characterization of two novel lymphocyte function-associated antigens, L24 and L25.

We describe the function and cell distribution of two novel cell surface antigens, L24 and L25. These antigens are broadly distributed on human lymphocytes. Monoclonal antibodies specific for these molecules block lysis by Class I- and II-specific cytotoxic T lymphocytes, but do not affect any other T cell functions tested. Anti-L24 antibody immunoprecipitates a molecule composed of two disulfide-linked monomers of 140 kd each. Anti-L25 antibody immunoprecipitates three proteins of 150, 85, and 75 kd. The study of these and other function associated molecules may provide insight into mechanisms of cytotoxic T lymphocyte recognition and/or function.

Antibodies, Monoclonal↗
PubMed1986

Function and cell distribution of KC-1, a novel natural killer cell-associated antigen.

Natural killer (NK) cell have been implicated in immune responses to tumor and viral antigens. We describe here a monoclonal antibody, anti-KC-1, that blocks lysis of NK targets by fresh but not activated NK cells. Anti-KC-1 has no effect on cytotoxic T lymphocyte activity or on antibody-dependent cellular cytotoxicity. This antibody may be useful in the analysis of NK cell activation and the mechanism of lysis.

Animals↗
PubMed1985

Determinants recognized by human cytotoxic T cells on a natural hybrid class I HLA molecule.

The major histocompatibility complex class I HLA molecules are the primary determinants recognized by allogeneic cytotoxic T lymphocytes (CTL), and serve as restricting elements for CTL recognition of viral, chemical, or minor histocompatibility antigens. HLA-Aw69 is a naturally occurring hybrid class I molecule that we have used to investigate the regions of class I antigens involved in human CTL recognition. HLA-Aw69 appears to have resulted from an exon shuffle between two closely related class I genes: the alpha 1 domain of HLA-Aw69 is identical to that of HLA-Aw68, while the alpha 2 and alpha 3 domains are identical to HLA-A2. The determinants recognized by human allogeneic CTL clones specific for HLA-A2, -Aw68, and/or -Aw69 fall into three patterns: (a) CTL determinants are located on both the alpha 1 and alpha 2 domains; (b) interaction of the alpha 1 and alpha 2 domains results in new combinatorial determinants; (c) interaction of the alpha 1 and alpha 2 domains in the hybrid molecule results in the loss of CTL determinants that are present on both parental molecules. Thus, using human CTL clones, target cells, and HLA molecules, we show that the interaction of the alpha 1 and alpha 2 domains alters CTL determinants in ways not directly predictable from primary structure.

Amino Acid Sequence↗
PubMed1985

Human T cell clones express functional homing receptors required for normal lymphocyte trafficking.

To function efficiently in vivo, lymphocytes must circulate from the blood into lymphoid tissues and other sites of immune reaction. Herein, we show that human cytotoxic and helper T cell clones and lines, maintained in vitro with IL-2, express the functional capacity to recognize and bind to high endothelial venules (HEV), a capacity essential for lymphocyte exit from the blood, and hence for normal lymphocyte trafficking. The expression of functional homing receptors distinguishes human T cell clones from their murine counterparts, which uniformly lack receptors for HEV and are unable to migrate normally from the blood in vivo. The results raise the possibility that human T cell clones may be more effective in mediating in vivo immune responses than is suggested by murine models.

Appendix↗
PubMed1985

Identification of a unique B-cell-stimulating factor produced by a cloned dendritic cell.

We describe a cloned dendritic cell, clone Den-1, which is a potent accessory cell for some B-cell responses. Clone Den-1 produces a unique lymphokine that induces polyclonal B-cell proliferation in the absence of other costimulators. This clone or factors produced by it also stimulate purified B cells to develop plaque-forming cell responses to type 2 antigens. The effect of this factor(s) on various B-cell populations and its relationship to previously described B-cell-stimulating factors is discussed.

Animals↗
PubMed1985

T cell regulation of antibody responses: an I-A-specific, autoreactive T cell collaborates with antigen-specific helper T cells to promote IgG responses.

In earlier studies we showed that hapten-specific inducer T cell clones specifically induce B cells from immunized donors to secrete IgM antibodies. However, IgG responses were not observed, suggesting that an additional signal(s) was required. In this report, we show that an autoreactive T cell clone produces a factor(s) that collaborates with antigen-specific inducer T cells to promote specific IgG responses. This factor is not restricted by antigen or MHC determinants and promotes IgG production both in vivo and in vitro. These findings suggest that autoreactive cells may play an important role in the regulation of isotype expression.

Animals↗
PubMed1985

B cell activation: role of dendritic and T cell factors in the response to thymic-independent and -dependent antigens.

We described a cloned dendritic cell, clone Den-1, that is a potent accessory cell for some B cell responses. Clone Den-1 produces a novel lymphokine that is distinct from previously described factors produced by T cells. In the present study, we compare the role of nonspecific helper factors produced by Den-1 (Den-1 SN) or the T cell thymoma EL4 (EL4-SN) in promotion of B cell plaque-forming cell (PFC) responses to a variety of antigens. We find that the antigen in culture determines the B cell requirement for dendritic and/or T cell factors. B cell PFC responses to TNP-Brucella abortus (BA) and TNP-lipopolysaccharide (LPS) are greatly increased by EL4-SN but show little, if any, enhancement with Den-1 SN. Responses to TNP-polyacrylamide are reconstituted by either Den-1 SN or EL4-SN, whereas responses to TNP-Ficoll, TNP-dextran and TNP-levan are reconstituted by Den-1 SN and are much less sensitive to factors present in EL4-SN. Responses to SRBC require the presence of both Den-1 SN and EL4-SN. We also show that the time at which Den-1 SN must be provided to the B cell is dependent on the antigen in culture. Our findings are discussed in terms of present classification of antigens based on their ability to stimulate various B cell subpopulations.

Acrylic Resins↗
PubMed1985

Target specificity and cell surface structures involved in the human cytolytic T lymphocyte response to endothelial cells.

Two long-term cytolytic T lymphocyte (CTL) lines derived from the peripheral blood lymphocytes (PBL) of a single donor were analyzed for target specificity and involvement of cell surface molecules in CTL-target interactions. One line, AH2, was generated after stimulation with B lymphoblastoid cells. Cytolysis by these cells was restricted to targets expressing the appropriate HLA-A2 specificity and was blocked by mAb recognizing CD2, CD3, CD8, LFA-1, and LFA-3. The second line, AE1, was generated after stimulation with cultured endothelial cells derived from human newborn preputial microvessels. These CTL lysed all human target cells tested, except autologous cells and the Class I negative cell line Daudi. In addition, mAb specific for CD2, CD3, and CD8 did not affect cytolysis. Anti-LFA-1 and -LFA-3 mAb blocked cytolysis of B lymphoblastoid targets but not endothelial targets. These results indicate that some CTL utilize as yet uncharacterized cell surface structures for CTL-target interactions.

Antigens, Surface↗
PubMed1985

Monoclonal helper T cells induce B cell responses to T-independent antigens: antigen-specific T cells are directly stimulated by activated B cells in the absence of antigen.

Efficient B cell responses to most polysaccharide antigens such as TNP-PAA or TNP-Ficoll require factors produced by activated T cells. However, the mechanism of T cell activation during such responses has not been established, because these antigens do not activate T cells, either directly or in conjunction with I-A gene products. We used a panel of antigen-specific monoclonal helper T cells to study T cell activation during the course of such responses. We show that activated I-A-identical B cells directly stimulate these monoclonal T cells, and that this stimulation is in the absence of nominal antigen. The high frequency of inducer cells that are stimulated by activated B cells suggests a major biologic role for this novel pathway of T cell activation.

Animals↗