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Jonathan P Schneck

Publications and source records attributed to Jonathan P Schneck.

15 recordsLinked to original sources
PubMed2006

Gld mutation of Fas ligand increases the frequency and up-regulates cell survival genes in CD25+CD4+ TR cells.

The Fas pathway and regulatory T (T(R)) cells play intertwining roles in controlling T cell tolerance through deletion and suppression of autoreactive T cells. Impairment of either mechanism causes severe T cell lymphoproliferation albeit with opposing outcomes. T cell lymphoproliferation induced by defective Fas pathway does not cause overt lymphocytic infiltration but rather prevents an important set of T cell-mediated autoimmune diseases. In contrast, deficiency in T(R) cell causes fulminant autoimmunity in very early life and fatal lymphocytic infiltration. These observations suggest existence of unidirectional fail/safe mechanism that compensate for defects in the Fas pathway but not in regulatory cells. To gain insights into how animals compensate for defects in the Fas system, we analyzed the impact of generalized lymphoproliferative disease (gld) mutation on survival, function and transcription profile of CD25+CD4+ T(R) cells. Our results show that all CD4 T cells expanded in gld mice. However, CD25+CD4+ T(R) cells are disproportionately increased in the pool of CD4 T cells perhaps due to their unique apoptosis phenotype. Freshly isolated CD25+CD4+ T(R) cells, unlike CD25-CD4+ T cells, are highly sensitive to FasL-induced apoptosis in the steady state. CD25+CD4+ T(R) cells that accumulate in gld mice express similar level of Foxp3, and have suppression potency and T(R) gene expression profile as wild-type CD25+CD4+ T(R) cells. Furthermore, the transcription profile of gld CD25+CD4+ T(R) cells is characterized by differential expression of genes involved in cell survival, metabolism and innate immune responses. These results provide a strong cellular and molecular basis for understanding why impaired Fas pathway prevents an important subset of T cell-mediated autoimmune diseases.

Animals↗
PubMed2005

Artificial antigen-presenting cells: artificial solutions for real diseases.

Adoptive immunotherapy, which involves the transfer of autologous antigen-specific T cells generated ex vivo, is a promising strategy to treat a variety of life-threatening diseases. Unfortunately, current approaches for generating sufficient numbers of antigen-specific T cells lack the ability to serve as reproducible and economically viable methods. This has spurred the development of both cell- and non-cell-based artificial antigen-presenting cells to alleviate problems associated with peptide-loaded dendritic cells in current approaches to adoptive immunotherapy. Here, we review new strategies for the ex vivo generation of antigen-specific T cells and their clinical application. These new approaches have the potential to spearhead a new era of successful adoptive immunotherapy for cancer and infectious diseases.

Animals↗
PubMed2005

Antigen/MHC class II/Ig dimers for study of uveitogenic T cells: IRBP p161-180 presented by both IA and IE molecules.

PURPOSE: Detection and modulation of effector T cells specific to immunodominant epitopes is a central issue in autoimmune diseases. Experimental autoimmune uveitis is a model for human autoimmune uveitis, induced in B10.RIII mice with interphotoreceptor retinoid binding protein or with its immunodominant epitope encoded by residues 161-180. METHODS: The authors generated a dimer composed of p161-180 fused in frame to IA(r) and mouse IgG1, and studied its effects on a CD4(+) uveitogenic T-cell line specific to p161-180 and on a T-cell clone derived from that line. RESULTS: Immunofluorescent staining of the T-cell line with the peptide/IA(r)/Ig dimer revealed that about 90% of the cells bound the reagent, and 10% did not. The T-cell clone failed to bind the reagent. Consistent with this, the line proliferated when stimulated with the reagent plus anti-CD28, and the clone did not. Conversely, after being incubated with the reagent without CD28 cross-linking, the line showed decreased proliferation on subsequent stimulatory exposure to p161-180, whereas the clone was unaffected. Antigen-specific proliferation of splenocytes from B10.RIII mice primed with p161-180 was inhibited by anti-IA as well as anti-IE antibodies; proliferation of the T-cell line was inhibited strongly by anti-IA and poorly by anti-IE, and the clone showed the opposite pattern. Finally, the line, but not the clone, proliferated to p161-180 presented on a B-cell lymphoma expressing IA(r) as its only restriction element. CONCLUSIONS: Uveitogenic T cells can be detected as well as functionally modulated with their cognate peptide-class II reagent, suggesting the potential of such reagents for diagnostic and therapeutic use in uveitic disease; p161-180 can be presented by IA(r) as well as IE(r) major histocompatibility complex (MHC) class II molecules. The possibility that the same immunodominant fragment might be presented by more than one class II molecule should be taken into account when diagnostic or clinical use of peptide-MHC reagents is considered.

Animals↗
PubMed2005

Evaluation of topoisomerase-1-specific CD8+ T-cell response in systemic sclerosis.

Measurement of disease activity in systemic autoimmune disorders is often unreliable, and immunosuppressive therapy is often titrated to crude clinical response and/or onset of complications. Systemic sclerosis (SSc) presents a distinct clinical phenotype associated with specific autoantibodies. Anti-topoisomerase-1 (SCL-70) is selectively detected in 30-60% of subjects with diffuse skin and interstitial lung involvement. Such patients offer an ideal clinical model to characterize and quantify the autoantigen-specific T-cell response and its correlation with disease phenotype and activity. Human leukocyte antigen A2 (HLA-A2)-restricted topo-1 peptides were selected based on an epitope prediction algorithm. For initial studies, the best binder topo-1(262-270) KMLDHEYTT (#262) was used alone or loaded onto an artificial antigen-presenting platform generated by coupling a dimeric major histocompatibility complex-immunoglobulin G fusion protein (HLA-A2-Ig) and anti-CD28 antibodies onto magnetic beads (artificial antigen-presenting cells). Blood samples (100 microL) from HLA-A2+ SSc patients and cytomegalovirus (CMV) seropositive healthy control subjects were tested in an intracellular cytokine staining assay. Gamma interferon production by CD8+ T cells was measured after stimulation with peptide #262, CMVpp65, or MART-1 (irrelevant peptide). In two of five SCL-70+ patients, peptide #262-loaded aAPCs induced a specific CD8+ T-cell response (0.45% +/- 0.23% of total CD8+ cells). This response was not observed in the seven SCL-70- (five SSc and two CMV+) control subjects studied (0.03% +/- 0.02%). Interestingly, bronchoalveolar lavage fluid obtained from one topo-1-responsive SSc patient who had worsening respiratory function and active alveolitis showed striking enrichment of topo-1-specific CD8+ T cells (3.94%). This small-volume ex vivo assay may prove to be a sensitive and specific tool to assess disease activity and to monitor response to therapy in patients with scleroderma.

Autoimmune Diseases↗
PubMed2005

Technological advances in adoptive immunotherapy.

Adoptive immunotherapy is an attractive and elegant strategy for treating a variety of life-threatening diseases. Several approaches have been developed to generate antigen-specific CD4+ and CD8+ T cells for adoptive T-cell therapy in cancer and infectious diseases. Currently, many approaches are based on either the use of autologous peptide pulsed dendritic cells as antigen-presenting cells or nonspecific expansion of T cells. Unfortunately, current approaches lack the ability to serve as reproducible and economically viable methods. Several groups are developing new artificial approaches to overcome problems associated with dendritic cells and the nonspecific expansion of T-cell clones in order to make adoptive immunotherapy more feasible and effective. Thus, by increasing the availability of adoptive immunotherapy, we will be able to better determine the efficacy of the approaches in the treatment of a variety of diseases. In this review, we focus on technological advances that will facilitate adoptive immunotherapy. Specifically, we summarize current strategies which are either based on artificial antigen-presenting cells or on T-cell receptor gene transfer.

Antigen-Presenting Cells↗
PubMed2004

Effect of human papillomavirus-16 infection on CD8+ T-cell recognition of a wild-type sequence p53264-272 peptide in patients with squamous cell carcinoma of the head and neck.

PURPOSE: Wild-type sequence (wt) p53 peptides are attractive candidates for broadly applicable cancer vaccines, currently considered primarily for patients whose tumors overexpress p53. Circumstances exist, however, where increased p53 degradation may result in appreciable presentation of p53-derived peptides, despite low p53 expression. Squamous cell carcinoma of the head and neck is associated with oncogenic human papillomavirus (HPV) subtypes, which inactivate p53 through proteasomal degradation. The criterion of p53 overexpression would exclude these individuals from wt p53-based immunotherapy. EXPERIMENTAL DESIGN: We tested the correlation of HPV infection with enhanced antigenicity of the p53 protein and postulated that removal of HPV-16(+) tumors with enhanced p53(264)-(272) peptide presentation might lead to a drop in T cells specific for this peptide in vivo. Circulating frequencies of T cells specific for the HLA A*0201:p53(264)-(272) complex were measured ex vivo using dimeric HLA:peptide complexes in 15 head and neck cancer patients before and 6 months after tumor excision. RESULTS: CD8+ T-cell recognition of HLA A*0201 restricted wt p53(264)-(272) peptide presented by HPV-16(-) squamous cell carcinoma of the head and neck lines was enhanced by HPV-16 E6 expression, sometimes exceeding that of a naturally transformed, HPV-16(+) wt p53 expressing squamous cell carcinoma of the head and neck cell line. In patients with HPV-16(-) tumors, the frequency of wt p53(264-272)-specific T cells remained largely unchanged after tumor removal. However, a significant decline in frequency of anti-p53(264-272) T cells was observed postoperatively in HPV-16(+) patients (P < 0.005). CONCLUSIONS: Recognition of HPV-associated squamous cell carcinoma of the head and neck appears associated with levels of wt p53-specific T cells and inversely with p53 expression. p53 peptides may be useful tumor antigens for squamous cell carcinoma of the head and neck immunotherapy in addition to viral gene products.

Aged↗
PubMed2004

HLA-Ig-based artificial antigen-presenting cells: setting the terms of engagement.

Recent advances in molecular medicine have shown that soluble MHC-multimers can be valuable tools for both the stimulation of as well as the analysis of antigen-specific T cells in vitro. In this review, we describe the use of dimeric major histocompatibility complexes, HLA-Ig, to visualize antigen-specific T cells as well as their potential to stimulate immune responses as part of an artificial antigen-presenting cell (aAPC). The use of HLA-Ig-based aAPC represents an exciting new approach to generate antigen-specific CTL for adoptive immunotherapy that helps to overcome many of the obstacles associated with limitations in current approaches to adoptive immunotherapy.

Animals↗
PubMed2004

Quality and quantity: new strategies to improve immunotherapy of cancer.

Adoptive immunotherapy is a promising approach for the treatment of infectious diseases and cancer. Several lines of research are currently focusing on the development of different technologies to facilitate the induction and expansion of antigen-specific T cells. Here, we discuss two current articles that affect the field of adoptive immunotherapy. One article describes the engineering of artificial antigen-presenting cells, which promise to replace the cumbersome dendritic-cell approach for the in vitro generation of large numbers of antigen-specific T cells. The second development is a description of a new technique for the detection of functionally active antigen-specific T cells, which will enhance the ability to control the quality of the T cells to be used in adoptive immunotherapy. Together, these exciting findings will advance the field of immunotherapy.

Animals↗
PubMed2003

B220+ double-negative T cells suppress polyclonal T cell activation by a Fas-independent mechanism that involves inhibition of IL-2 production.

Fas-mediated apoptosis is a key mechanism for elimination of autoreactive T cells, yet loss of function mutations in the Fas signaling pathway does not result in overt T cell-mediated autoimmunity. Furthermore, mice and humans with homozygous Fas(lpr) or Fas ligand(gld) mutations develop significant numbers of B220+ CD4- CD8- double-negative (DN) alphabeta T cells (hereafter referred to as B220+ DN T cells) of poorly understood function. In this study, we show that B220+ DN T cells, whether generated in vitro or isolated from mutant mice, can suppress the ability of activated T cells to proliferate or produce IL-2, IL-10, and IFN-gamma. B220+ DN T cells that were isolated from either lpr or gld mice were able to suppress proliferation of autologous and syngeneic CD4 T cells, showing that suppression is Fas independent. Furthermore, restoration of Fas/Fas ligand interaction did not enhance suppression. The mechanism of suppression involves inhibition of IL-2 production and its high affinity IL-2R alpha-chain (CD25). Suppression also requires cell/cell contact and TCR activation of B220+ DN T cells, but not soluble cytokines. These findings suggest that B220+ DN T cells may be involved in controlling autoreactive T cells in the absence of Fas-mediated peripheral tolerance.

Animals↗
PubMed2003

Ex vivo induction and expansion of antigen-specific cytotoxic T cells by HLA-Ig-coated artificial antigen-presenting cells.

Adoptive immunotherapy holds promise as a treatment for cancer and infectious diseases, but its development has been impeded by the lack of reproducible methods for generating therapeutic numbers of antigen-specific CD8(+) cytotoxic T lymphocytes (CTLs). As a result, there are only limited reports of expansion of antigen-specific CTLs to the levels required for clinical therapy. To address this issue, artificial antigen-presenting cells (aAPCs) were made by coupling a soluble human leukocyte antigen-immunoglobulin fusion protein (HLA-Ig) and CD28-specific antibody to beads. HLA-Ig-based aAPCs were used to induce and expand CTLs specific for cytomegalovirus (CMV) or melanoma. aAPC-induced cultures showed robust antigen-specific CTL expansion over successive rounds of stimulation, resulting in the generation of clinically relevant antigen-specific CTLs that recognized endogenous antigen-major histocompatibility complex complexes presented on melanoma cells. These studies show the value of HLA-Ig-based aAPCs for reproducible expansion of disease-specific CTLs for clinical approaches to adoptive immunotherapy.

Antigen Presentation↗
PubMed2002

Peptide-beta2-microglobulin-MHC fusion molecules bind antigen-specific T cells and can be used for multivalent MHC-Ig complexes.

Recombinant soluble MHC molecules are widely used for visualization, activation and inhibition of antigen-specific immune responses. Using a genetic approach, we have generated two novel peptide-beta2-microglobulin-MHC constructs. We have linked the MHC molecule with the peptide of interest, without limiting the recognition by the cognate TCR. This molecule can also be joined with the IgG heavy chain resulting in a dimeric MHC-Ig fusion protein. These molecules bind antigen-specific T cells with high specificity and sensitivity, therefore, providing a valuable tool for detection as well as enrichment of antigen-specific T cells.

Animals↗
PubMed2002

Probing T cell membrane organization using dimeric MHC-Ig complexes.

In this report, we review a novel method for probing the membrane organization of T cells using dimeric major histocompatibility complexes (MHC), MHC-Ig. MHC-Ig complexes are useful reagents for quantitative analysis of binding data since their valency is controlled. These complexes can be easily labeled and loaded with a variety of peptides. A binding assay using these dimers and quantitative analysis of the MHC-Ig dimer-T cell binding curves is described in detail. Using this approach, we show that the organization of TCR on activated T cells is different from TCR organization on nai;ve T cells. The implications of these findings are discussed with regards to current models of T cell recognition. This analysis offers insight into how T cell controls their biological range of responsiveness. Specifically, these findings reveal the biophysical basis of the ability of activated T cells to recognize low amounts of antigen independent of costimulation.

Animals↗
PubMed2002

T cell immunodominance and maintenance of memory regulated by unexpectedly cross-reactive pathogens.

We show here that T cell cross-reactivity between heterologous viruses influences the immunodominance of virus-specific CD8(+) T cells by two mechanisms. First, T cells specific for cross-reactive epitopes dominate acute responses to viral infections; second, within the memory pool, T cells specific for cross-reactive epitopes are maintained while those specific for non-cross-reactive epitopes are selectively lost. These findings suggest an immunological paradigm in which viral infections shape the available T cell repertoire, causing alterations in the hierarchies of both the primary and memory CD8(+) T cell responses elicited by subsequent viral infections. Thus, immunodominance is a function of the host's previous exposure to unrelated pathogens, and this may have an impact on protective immunity and immunopathology.

Animals↗
PubMedDate not supplied

Detection of antigen-specific T cells on p/MHC microarrays.

The development of high-throughput protein microarrays for rapidly determining antigen-specific T-cell receptor repertoires of diverse T-cell populations can enable comprehensive, broad-based analyses of T-cell responses. Promising applications include medical diagnostics, vaccine development, treatment of autoimmune diseases and detection of potential agents of bioterrorism. In this study, we examined the feasibility of using peptide/major histocompatibility complex (p/MHC) microarrays to selectively capture and enumerate antigen-specific T cells. Results are presented for p/MHC microarrays consisting of a dimeric MHC-immunoglobulin complex, K(b)-Ig, loaded with either a cognate or non-cognate peptide for binding CD8(+) T cells. We quantified the sensitivity of these K(b)-Ig microarrays by measuring a lower detection limit of 0.05% antigen-specific CD8(+) T cells mixed with splenocytes from C57BL/6J mouse. A fivefold increase in this lower detection limit (0.01%) was achieved using a secondary capture anti-Ig antibody to coat the microarray surface. This higher sensitivity is comparable to that obtained using standard state-of-the-art fluorescence activated cell sorting (FACS) instruments. We also found that contacting the T-cell suspension with the K(b)-Ig microarrays under mild shear flow conditions produced more uniform distributions of captured T cells on the individual spots and better spot-to-spot reproducibility across the entire microarray.

Animals↗