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P Lake

Publications and source records attributed to P Lake.

At least 37 records · Page 2Linked to original sources
PubMed1987

Topographical and conformational epitopes of bovine papillomavirus type 1 defined by monoclonal antibodies.

Monoclonal antibodies (MAbs) were generated against sodium dodecyl sulfate-disrupted bovine papillomavirus type 1 (BPV-1). When screened by enzyme-linked immunosorbent assay (ELISA) on intact and disrupted BPV-1, -2, and deer papillomavirus, three patterns of reactivity were defined: reactivity only with intact virus, with both intact and disrupted virus, and only with disrupted virus. On the basis of ELISA results, the topographical location and requirement for conformation for immunoreactivity of epitopes was defined as external conformational, external linear, and internal linear. Cross-reactivity of MAbs with other papillomavirus types was analyzed by immunofluorescence on warts from different species. Type-specific, BPV-1 and/or -2 cross-reactive, broadly cross-reactive, and genus-specific MAbs were identified. MAb reactivity with structural polypeptides of BPV-1 was analyzed by Western blot. MAbs reactive with epitopes defined as conformational by ELISA did not react in Western blot. All MAbs reactive in Western blot reacted with the major capsid protein (MCP) [55 kilodalton (kDa)], demonstrating that the MCP carries both type-specific and cross-reactive epitopes. Most MAbs reactive with the MCP were cross-reactive with structural polypeptides of 48 and 96 kDa, demonstrating the immunologic relatedness of these three polypeptides.

Animals↗
PubMed1986

Functional interactions of human and murine lymphoid cells. I. Analysis of primary and secondary responses.

In this study human T-cell responses against murine alloantigens were analyzed. The results show that optimal primary responses are obtained from peripheral blood mononuclear cells only when murine splenic adherent cells (SAC) were used as antigen. Further analysis revealed that human T cells were able to respond directly to murine cells without the need for antigen reprocessing; however, human interleukin 1 (IL-1) was required for optimal stimulation. In contrast, secondary proliferative responses to murine cellular antigens could be induced from primed T cells even in the absence of SAC and/or IL-1. These proliferative responses, and in addition, cytotoxic T-cell responses, were specific for the priming antigen. Long-term human T-cell lines specific for murine alloantigens were found to replace the need for murine T cells in antigen-specific murine B-cell responses to sheep red blood cells. The mechanism of help delivered by the human T cells appeared to be by the release of nonspecific helper-T-cell factors. The evidence presented for this is the inability of these cells to stimulate cells from mice that express the X chromosome B-cell defect xid.

Animals↗
PubMed1986

T-cell replacing factor activity of recombinant-derived interleukin-2 requires gamma-interferon.

In this study we show that recombinant-derived human interleukin-2 (rIL-2) has potent T-cell replacing activity in antigen-driven murine antibody responses of T-depleted spleen cells. This T-cell replacing factor (TRF) effect of rIL-2 is antigen specific. By the use of a variety of antibodies to gamma-interferon (IFN-gamma), including antibody from an interspecies hybridoma, we demonstrate that this TRF activity depends upon the production of IFN-gamma in the responding cell cultures, i.e., antibody to IFN-gamma blocks TRF activity. In addition, we show that the cell-to-cell allogeneic helper effect of T cells for antibody responses is similarly inhibited by antibodies to IFN-gamma. The inhibition of response produced by the antibodies is reversed by the addition of excess rIFN-gamma to the cultures. The results demonstrate that IFN-gamma is a necessary intermediate mediator for TRF activity mediated by IL-2 and also by T-cell-mediated help for B cells. Thus, even recombinant-derived lymphokines have complex secondary levels of action on responding cells. Antibodies to individual lymphokines are clearly a powerful resource to analyze the role of soluble factors in cellular responses.

Animals↗
PubMed1985

Obligatory role of gamma interferon in T cell-replacing factor-dependent, antigen-specific murine B cell responses.

The role of gamma interferon (IFN-gamma) in T cell-replacing factor (TRF) activity for antigen-specific plaque-forming cell (PFC) responses in vitro was studied using antibodies to murine IFN-gamma (Mu IFN-gamma). TRF activity was present in supernatants (Sn) of Con A- or mixed leukocyte reaction-stimulated murine spleen cells as well as in an IL-2-rich fraction of phytohemagglutinin-stimulated human peripheral blood lymphocyte Sn and in the Sn of the Gibbon T lymphoma MLA-144. The human TRF was highly active with cells from nu/nu mice and normal mice but not with cells from animals with the xid immunologic defect, similar to the activity of murine TRF. Antibodies to IFN-gamma consisted of hyper-immune rabbit antisera, IFN-gamma affinity-purified rabbit immunoglobulin and an interspecies hybridoma specific for Mu IFN-gamma. The results show that the activities of all preparations of TRF are markedly diminished or abrogated by antibody to Mu IFN-gamma but not by antibodies to human IFN-gamma (Hu IFN-gamma), nor by normal rabbit sera or purified rabbit Ig. The degree of inhibition was dose dependent and was quantitatively reversed by the addition to the cultures of recombinant-derived Mu IFN-gamma (Mu rIFN-gamma) but not Hu rIFN-gamma. This reversal was fully antigen specific and thus not attributable to polyclonal B cell activation by IFN-gamma, which is inactive alone in the TRF assay. Kinetic analysis shows that IFN-gamma must act by 24-48 h to produce PFC responses at 4 d. Together, the data demonstrate that IFN-gamma is a necessary mediator for TRF effects and that IFN-gamma is induced by TRF from T-depleted murine spleen cells in sufficient quantity to support large antibody responses. The source of this IFN-gamma may be the potent natural killer cells that are induced in cultures stimulated with TRF.

Animals↗
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

Cellular mechanism of primary anti-Thy-1 antibody responses in vitro induced by uniquely immunogenic thymocyte antigens.

Thy-1 antigens are the only cell membrane antigens known to be able to induce primary antibody responses in vitro. We have shown that antigens from the thymocytes of mice and rats were highly immunogenic in cultures of murine spleen cells for the induction of Thy-1.1-specific plaque-forming cell responses, whereas antigens from other tissues, including brains and bone marrow, were poorly immunogenic, if at all. The thymocyte-specific Thy-1 immunogenicity was carried by disrupted cell membranes, and the specific activity for inducing responses was closely linked to Thy-1. We then tried to determine the mechanism of anti-Thy-1 antibody responses in vitro that were induced by the uniquely immunogenic thymocyte antigens. The thymocyte Thy-1 antigens behaved as T cell-independent class 2 (TI-2) antigens: they induced responses in athymic nude mice but not in CBA/N mice with a B cell defect. The apparent TI-2 responses to thymocyte Thy-1 did, however, require Thy-1+ cells in the responder, similar to anti-DNP-Ficoll responses. The full development of the anti-Thy-1 responses required the participation of splenic adherent cells (SAC). Nevertheless, the mechanism of the SAC dependency of anti-Thy-1 responses did not involve antigen presentation to lymphocytes by antigen-pulsed SAC, which contrasted with the finding that the presentation of antigen by live SAC to lymphocytes was indispensable for responses to DNP-Ficoll. The poor Thy-1 responsiveness of SAC-depleted spleen cells was fully restored by the addition of soluble factors (IL 1-like molecules) released from SAC into the culture, which did not replace the SAC-requirement of responses to DNP-Ficoll. It was concluded from these results that Thy-1 or Thy-1-linked structures on thymocyte membranes have an intrinsic activity to directly signal either TI-2 B cells or immature T cells, or both, for activation in the presence of soluble factors released from adherent accessory cells. This conclusion is discussed in relation to a hypothetical view that the thymocyte Thy-1 would physiologically mediate cell-to-cell interactions among special subsets of lymphocytes under thymic influence.

Animals↗
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

Intact and subcellular form of thymocytes of rats are exceptionally immunogenic in mice for inducing anti-Thy-1 T cell-independent class 2 antibody responses.

Results of the present study show that the primary anti-Thy-1.1 antibody response to rat antigen in Thy-1.2 mice is induced exclusively by thymocyte antigen. Thy-1 antigens of brain and bone marrow, which expressed much Thy-1 antigen, were poorly immunogenic if at all. Brain Thy-1 antigen considerably inhibited the immunogenicity of thymocyte Thy-1. Moreover, we found that subcellular form of thymocytes induce as high antibody responses as intact thymocytes do. The subcellular thymocyte Thy-1 antigen behaved as TI-2 antigen, inducing a good response in athymic nude mice but not in CBA/N mice with a B cell defect. The significance of these findings is discussed in relation to the possible physiological activity of Thy-1 or Thy-1-linked molecules on thymocytes specifically mediating lymphocyte differentiation.

Animals↗
PubMed1983

Cloned measles virus-specific T lymphocytes from a twin with multiple sclerosis.

A measles virus-specific T lymphocyte clone derived from a measles-responder twin with multiple sclerosis has been produced. The cloned cells proliferate in response to measles virus but not mumps, vaccinia, or canine distemper viruses. The clone recognizes an antigen that is distributed in both the membrane and cytoplasmic fractions of cells infected with measles virus. Antigen is presented to the clone equally well by irradiated mononuclear cells obtained from the autologous subject and from her healthy, measles-nonresponder, HLA-identical twin. Studies with a panel of HLA-typed irradiated mononuclear cells indicate that antigen is presented to the clone in the context of a gene product linked to, but not identical with, HLA-DRw2. The clone produces interleukin 2 and has surface determinants recognized by OKT-3, OKT-4, and anti-HLA-DR monoclonal antibodies, but not by OKT-8. It thus appears to belong to the helper/inducer subpopulation of T lymphocytes.

Antigens, Viral↗
PubMed1983

Evidence for the erythrocyte as the principal antigenic cell type that triggers primary IgM antibody responses to H-2D alloantigens.

Antigenic requirements for the induction of T cell-independent primary splenic IgM antibody responses (plaque-forming cell responses) to H-2Dd alloantigens were studied. Results show that some functional activity or structural property of the donor cells is required for immunogenicity, because antigens are not active in subcellular forms. An unexpected finding was that allogeneic red blood cells were exceptionally highly immunogenic, and any lymphoid tissues including purified macrophages and tumor cell lines that were not contaminated with red blood cells were virtually nonimmunogenic. The definite role of red blood cells in donor tissues as immunogens was confirmed by water or ammonium chloride treatment that abolished immunogenicity, as well as by phenotyping of the immunogenic cells with antisera. Thus immunogenic cells were positive for erythrocyte-specific and H-2D antigens and negative for Thy-1, Ig, and NK-1. The possible roles of erythrocytes in induction and regulation of transplantation immunity and in B cell activation in general are discussed.

Animals↗
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

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↗