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D D Eckels

Publications and source records attributed to D D Eckels.

At least 55 records · Page 3Linked to original sources
PubMed1988

Peptide-mediated modulation of T-cell allorecognition.

Antigen-specific helper T cells recognize a complex of peptide antigen and class II major histocompatibility complex (MHC) gene products. Whether T cells recognize MHC class II alloantigen by a similar mechanism or the native conformation of MHC molecules themselves has yet to be determined. The demonstration that peptide antigens bind directly and specifically to class II molecules has allowed us to examine the influence of foreign peptide binding on T-cell recognition of allogeneic MHC molecules. We report here that an immunodominant, HLA-DR1-restricted peptide of influenza virus hemagglutinin (HA residues 306-320) is able to modulate the recognition of alloantigen by human DR1-specific T-cell clones. For some T-cell clones, but not all, the HA peptide inhibited allorecognition in a dose-dependent manner. However, in one instance, the proliferative response to alloantigen was enhanced in the presence of HA peptide. These results suggest that the specificities of T-cell responses to allogeneic MHC molecules are heterogeneous, which may be influenced by different peptides occupying the class II MHC combining site and by the diversity of antigen-specific receptors of T lymphocytes recognizing the same MHC/peptide complex.

Amino Acid Sequence↗
PubMed1988

MHC class II restriction specificity of cloned human T lymphocytes reactive with Dermatophagoides farinae (house dust mite).

In this report the antigen and restriction specificity of human T-cell clones induced with Dermatophagoides farinae (D. farinae) and isolated from an atopic individual with perennial rhinitis has been investigated. Of the six clones analysed, four were species specific and two showed cross-reactivity for the closely related Dermatophagoides pteronyssinus (D. pteronyssinus). Inhibition of antigen-dependent proliferation by murine monoclonal antibodies directed against HLA-D-region gene products revealed that all the clones were restricted by HLA-DR molecules. The restriction specificity was investigated further using a panel of histocompatible and allogeneic-presenting cells. Of the clones tested, one appeared to be DR5 restricted while the remainder showed complex patterns suggesting that DRw52 and DRw53 supertypic specificities may be the restriction elements presenting antigen.

Allergens↗
PubMed1986

Recognition of a hybrid HLA-DP-associated determinant by a human T lymphocyte clone.

Alloreactive, human T cell clones were derived from an HLA-DPw1-specific primed lymphocyte typing cell line by limiting dilution. The specificities of the clones were analyzed with allogeneic stimulator cells and in family segregation studies. One clone, TLC 56.94, recognized some, but not all, DPw1-positive stimulator cells and in two families, failed to proliferate in response to stimulatory cells from DPw1-homozygous individuals. The simplest explanation for these results is that TLC 56.94 recognizes a hybrid alloantigen produced by transcomplementation or transassociation between an element of DPw1 and some other gene product.

Antibodies, Monoclonal↗
PubMed1986

Human allospecific TLCs generated against HLA antigens associated with DR1 through DRw8. I. Growth and specificity analysis.

To study the fine specificity of the HLA-D region, a panel of human T-lymphocyte clones (TLCs) was generated against alloantigens associated with HLA-DR1 through DRw8. HLA-DR-homozygous peripheral blood lymphocytes (PBLs) were stimulated with DR-heterozygous PBLs in primary mixed lymphocyte cultures for 4 days. Blasts were cloned by limiting dilution at 0.3 cells/well in the presence of 20% T-cell growth factor and irradiated stimulator cells. Viable clones were subsequently tested in proliferation assays against the original stimulator and a limited panel of stimulators bearing relevant DR specificities. Initial primings produced approximately 800 clones; some recognized DR-associated antigens, 70 recognized only their original stimulator, and approximately 50% were nonresponsive. Analysis on extended stimulator panels revealed alloantigenic complexity within similar DR-associated antigens as recognized by TLCs. The data are consistent with evidence that extreme heterogeneity exists within the HLA-D region.

Clone Cells↗
PubMed1986

Human allospecific TLCs generated against HLA antigens associated with DR1 through DRw8. II. Population analyses and blocking studies with monoclonal antibodies.

Serologic, cellular, and molecular evidence supports the concept of extreme complexity within the HLA-D region. To study the complexity and fine specificity of the HLA-D region at the level of T-cell recognition, a panel of T-cell clones was generated against alloantigens associated with HLA-DR1 through -DRw8. After initial screening of more than 800 clones, 89 representative lines were selected for extensive testing against 204 unrelated stimulator cells. Clone-by-clone correlation analyses were performed to test whether any clones recognized similar or identical epitopes. In addition, clonal reactivity patterns were correlated with known HLA specificities. Twelve clusters of clones were identified with similar reactivity patterns using clone-by-clone correlation analysis. Some groups were significantly correlated with specificities associated with various D-region haplotypes; others had no significant correlation with any defined D-region specificity. Five general types of clones obtained in our study can be categorized as follows: Those recognizing epitopes clearly demonstrating a primary association with the classically defined D-region molecules against which the clones were primed. Clones recognizing epitopes associated with one of the priming antigens and also with another unrelated D-region specificity. Clones detecting epitopes which showed significant correlation with D-region molecules totally different from those against which they were originally primed. Clones with limited reactivity in population studies and no correlation with defined D-region molecules. Clones recognizing class I-associated epitopes.

Antibodies, Monoclonal↗
PubMed1986

Clonal analysis of HLA-DPw1 (SB1) associated allodeterminants: recognition of novel epitopes and evidence for quantitative variation in class II antigen expression.

Alloreactive human T-lymphocyte clones were derived from the SB1 HLA-DPw1)-specific, primed lymphocyte typing cell line SB1A used in the Ninth International Histocompatibility Workshop. The clones from two separate subclonings were analyzed for their proliferative patterns in panel experiments with cells from unrelated individuals and in family segregation analyses. While only one clone gave a perfect correlation with the DPw1 specificity, the maturity of clones recognized multiple specificities apparently associated with but not identical to HLA-DPw1. Most clones defined "splits" or subsets of DPw1 and some also displayed "extra" reactions with DPw1-negative stimulator cells. Further evidence was also found that, of the molecules bearing epitopic subsets associated with DPw1, some may be selectively expressed on the cell surface whereas the surface density of other DPw1-associated antigens may be varied. Thus, the HLA-DP region appears to encode a complex array of alloantigens and is in this regard similar to the HLA-DR region.

B-Lymphocytes↗
PubMed1985

Longevity of human allospecific TLCs: mycoplasma infection as a cause of in vitro "suppression" of MLC.

It has been suggested that allospecific T-cell clones lose specific reactivity after approximately 30 cell doublings and subsequently acquire suppressor and NK-like characteristics. We have tested this hypothesis by assaying paired functional and nonfunctional TLCs for suppressor activity in PLT and MLC cocultures. Two sets of clones were initially studied: the first pair consisted of clone S5.2B, a functional TLC, and S5.14A, a nonfunctional TLC; the second pair of clones tested was comprised of two different expansions of the same clone S5.5A (nonfunctional) and S5.5B (functional). These experiments yielded no evidence for suppressive activity by nonfunctional clones toward functional clones, furthermore, the addition of nonfunctional clones to primary MLC assays had no effect on the level of responsiveness. Eight clones were subcloned and 89 subclones were retested for function after approximately 50 cell doublings. Generally, the subclones failed to suppress MLC proliferation. A minority of TLCs could suppress MLC responses, but this "suppression" was reversible with the addition of 2% exogenous TCGF. However, eight subclones and two parental TLC lines did suppress MLC responses in the presence or absence of TCGF, but the suppressive effects in such cocultures were reversible in the presence of tylocine, an anti-mycoplasma antibiotic. Therefore, human T-cells, cultured for extended periods, do not inexorably and universally lose specific alloreactivity and gain suppressive characteristics due to some presumed differentiative event.

Clone Cells↗
PubMed1984

Inhibition of T cell proliferation by antibodies to synthetic peptides.

While T cell proliferation to antigen in the presence of antigen-presenting cells is well known to be readily inhibited by antibodies directed against Class II major histocompatibility complex (MHC) (Ia/HLA-DR) products, it has not been possible to inhibit proliferation by antibodies directed against the antigen. Because of the implications of these observations for targets of T cell recognition, this phenomenon was reinvestigated using human T cell clones, recognizing a small (24 amino acid) synthetic peptide (termed p20) derived from the influenza hemagglutinin-1 molecule. It was found that proliferation of clones to p20 was inhibited efficiently (less than 90%), using p20 as antigen, and rabbit anti-p20. Inhibition was possible either by coculturing p20 antigen and antibody to p20 with cloned T cells and antigen-presenting (E-) cells, or by pulsing antigen-presenting cells with antigen prior to a brief incubation with antibody before washing the E- cells and using them to stimulate cloned T cells. These results do not indicate why previous attempts had failed, but in view of the different techniques available now (cloned T cells, small synthetic polypeptides, and antibody raised against polypeptide) we investigated the influence of these parameters. It was found that, using cloned T cells, the form of the antigen was of importance, as antibody inhibition of the response to hemagglutinin or whole influenza A was much less apparent. These differences were interpreted as being due to greater access of anti-p20 to p20 than to hemagglutinin or influenza. If uncloned T cell lines were used, inhibition was also much harder to detect. This was interpreted as masking of inhibition of the response of some clones in the line by interleukin 2-induced recruitment.

Animals↗
PubMed1984

Human helper T-cell clones that recognize different influenza hemagglutinin determinants are restricted by different HLA-D region epitopes.

Human T-lymphocyte clones ( TLCs ) were generated against the hemagglutinin (HA) of A/Texas/1/77 influenza virus by limiting dilution. TLCs were then screened for antigen specificity on chemically synthesized peptides representing the HA1 molecule. It has been hypothesized that different T cells that recognize the identical antigenic determinant are controlled by (restricted by) the same class II epitope. Two TLCs , HA1.4 and HA1.7, both recognized the same HA peptide and in proliferation studies exhibited identical restriction patterns. Two other clones, HA 1.9 and HA 2.43, recognized different HA determinants and also had distinct restriction patterns. Proliferation inhibition studies with monoclonal antibodies against human class II molecules demonstrated three unique patterns of blocking with the clones, suggesting that clones may be restricted to a unique class II epitope depending on the HA determinant recognized. These data can be interpreted as supporting the argument that human immune responses to influenza hemagglutinin are under Ir gene control exerted at the level of the viral antigenic determinant recognized in association with particular D-region restricting elements. The determinant selection and clonal deletion theories are compared for their capacity to best explain these findings.

Antibodies, Monoclonal↗
PubMed1983

SB-restricted presentation of influenza and herpes simplex virus antigens to human T-lymphocyte clones.

The HLA-D region of the human major histocompatibility complex (MHC) has been shown to be homologous to the murine I region in terms of both structure and function. Both regions encode class II MHC molecules which restrict T-lymphocyte interactions with antigen-presenting cells. We have recently described the MHC restriction and antigen specificities of human T-lymphocyte clones directed at strain A influenza virus. The majority of T-lymphocyte clones recognized antigen in the context of cell surface interaction products encoded by HLA-D/DR genes. However, a few clones recognized antigen presented by cells histoincompatible for D/DR antigens. We report here that some of these clones recognized viral antigens in association with antigens encoded by genes identical with or closely linked to the recently described secondary B-cell (SB) locus of the MHC. This is the first report that SB-restricted antigen recognition may form an integral part of normal, human immune responses.

Antigens, Viral↗
PubMed1983

The dissociation of interleukin-2 production and antigen-specific helper activity by clonal analysis.

Influenza virus immune human T-lymphocyte clones maintained in continuous culture in TCGF were analysed for helper activity and interleukin-2 (IL-2) production. The clones that functioned as helper cells in the production of specific antibody failed to release detectable amounts of IL-2. Conversely, the T cells that produced IL-2 were unable to provide either specific or non-specific helper function. These findings indicated the IL-2 is not an essential component for helper activity. However, phenotypic analysis revealed that both the functional subsets of T-cell clones expressed the helper phenotype in that they were T4+, T3+ and T11+. Nevertheless analysis with other antibodies revealed differences in that the IL-2 releasing clone showed greater staining with the anti-T-cell subset antibodies 9.3 and Leu 8, confirming that there is phenotype as well as functional heterogeneity within the helper inducer T-cell population.

Antibodies, Viral↗
PubMed1982

Characterization of human T-lymphocyte clones (TLCs) specific for HLA-region gene products.

Clones of lymphocytes, primed in vitro to HLA-DR1;Dw1, were tested for allospecific proliferation on a panel of thirty-one HLA-phenotyped stimulating cells. No clone was restimulated exclusively by cells sharing the DR1;Dw1 priming antigens and most clones were restimulated by subsets of cells bearing DR1;Dw1. Generally, positive responses were at least 20-fold higher than autologous negative controls. Peak proliferative responses occurred around 72 h and varied, depending on the stimulating cell as well as the responding clone. Selected clones were induced to proliferate only by cells incapable of forming rosettes with sheep erythrocytes. Specific proliferation by TLCs was blocked by monoclonal DR-specific antibodies, but not by monoclonal anti-Thy 1.2. Genetic studies demonstrated that TLCs detected some cell-surface determinants that are encoded by genes in linkage disequilibrium with HLA and others that may not be linked to the human major histocompatibility complex.

Antibodies, Monoclonal↗
PubMed1982

Antigen-specific human T-lymphocyte clones. Genetic restriction of influenza virus-specific responses to HLA-D region genes.

Human T lymphocytes, primed in vitro to influenza virus, were cloned by limiting dilution and expanded using medium containing interleukin 2 and feeder cells. A detailed analysis of the genetic requirements for induction of T-cell proliferation was conducted using a panel of cells from unrelated donors and two families who had previously been extensively phenotyped for HLA region antigens. Clones obtained from a Dw1, Dw3 individual required Dw1,DR1 histocompatibility for successful presentation of viral antigens by antigen-presenting cells. The antigen-presenting ability segregated with HLA-B,D,DR in an informative HLA-A/B recombinant individual. In contrast, some TLCs responded to antigen presented by cells that did not share known HLA antigens, and in one informative family, reactivity did not segregate with HLA. None of the T-cell clones reacted to allogeneic cells in the absence of antigen, suggesting that the TLCs do not bear receptors that recognize both influenza virus and alloantigen. In antibody-blocking studies, Dw1, DR1-restricted clones were blocked by all monoclonal anti-DR framework antibodies. The non-HLA-restricted TLCs were blocked by some, but not all, of the anti-DR framework monoclonal antibodies. These results confirm and extend the role of HLA-D region gene products in antigen presentation and also provide evidence that yet undefined cell interaction products, which may include hybrid structure, are able to participate in antigen-specific proliferative responses by human T cells.

Antibodies, Monoclonal↗
PubMed1982

Antigen-specific human T lymphocyte clones: induction, antigen specificity, and MHC restriction of influenza virus-immune clones.

Human peripheral blood lymphocytes from an HLA-Dw1,3 individual were primed in vitro with influenza A virus (A/Texas/1-77/x-49) and subsequently cloned by limiting dilution in TCGF. Of the 96 TLCs originally obtained, nine were characterized in detail. TLCs were antigen specific, responding to influenza A virus, not to influenza B, TGAL, GAT, tetanus toxoid, or KLH, and only when antigen was presented by cells unable to form rosettes with AET-treated SRBC. Presentation of antigen by unseparated PBL often resulted in significant "back stimulation," probably via production of growth factors. The MHC requirements for the induction of TLC proliferation were analyzed. Of four representative clones analyzed, three required Dw1;DR1 compatibility for successful presentation of viral antigens by a panel of antigen-presenting cells. In contrast, one TLC showed an unusual pattern of response that could not be correlated to a particular HLA haplotype. Monoclonal anti-T cell antibody analysis of the surface phenotype of two TLCs maintained in continuous culture for 5 mo indicated that they were OKT3+, 4+, and 8-, consistent with an inducer/helper phenotype. To confirm the clonal nature of TLCs, data on the functional properties of TLC subclones are also presented.

Clone Cells↗
PubMed1982

Antigen-specific human T lymphocyte clones: viral antigen specificity of influenza virus-immune clones.

Human T lymphocyte clones (TLC) specific for type A (A/Texas/1/77) influenza virus and maintained in continuous culture with T cell growth factor, were analyzed to define the cellular specificity pattern of virus recognition. A panel of TLC were stimulated with strains of serologically characterized type A influenza subtypes. Five TLC recognized all the viral subtypes; the remaining clones recognized only subtypes that shared serologically defined determinants with the immunizing subtype. In addition, the 11 TLC were analyzed for their fine antigenic specificity by using the purified viral components hemagglutinin (HA), neuraminidase (NA), matrix protein (MP), and nucleoprotein (NP). Five TLC proliferated in response to NA, four to MP, one to HA, and one to NP. None of the clones responded to the unrelated B strain influenza virus, B/Singapore. Furthermore, the fine specificity of an MP-reactive TLC was confirmed by subcloning.

Antigens, Viral↗