Differential therapeutic modulation of exhaustion among autoreactive and global CD8 T cells in type 1 diabetes (T1D)

Islet-specific CD8 T cell exhaustion (TEX) is linked to slower progression of type 1 diabetes (T1D). However, in the therapeutic setting, only global TEX has been studied. Here we address whether TEX among autoreactive cells in clinical trials relates to better outcome. We assessed PBMCs from select T1D subjects who had variable preservation of pancreatic function two years after treatment with teplizumab (anti-CD3, n=7) or alefacept (LFA3-Ig, n=12). We applied a CyTOF panel incorporating pooled pancreatic islet autoantigen peptide-loaded MHC Class I tetramer and 18 phenotyping markers. CD8 T cell subsets were identified by DISCOV-R multidimensional clustering analysis and were applied to samples with >5 autoreactive cells. Better clinical outcome was linked to greater frequencies of global CD8 TEX (subsets expressing PD1, EOMES, TIGIT, and KLRG1): a PD1hi subset 2 months after teplizumab (p=0.049) and a CD57hi subset 2 years following alefacept (p=0.044) treatment. Overall, increases in islet-specific TEX were rarely detected in poor responders (1 of 8 subjects with detectable islet-specific cells) consistent with a lack of change in global TEX, However, in subjects with better preservation of beta cell function, islet-specific TEX increased in fewer subjects (2 of 6) than global CD8 T cells (4 of 8). Together these results indicate that islet-specific CD8 T cells only partially mirror global CD8 responses, and further research is needed to clarify the role of exhaustion and its relation to autoreactive T cells in determining outcome in therapeutic settings.

Supported by grants from NIH (R01 AI141952) and Immune Tolerance Network (UM1AI109565).

Immunological biomarkers: catalysts for translational advances in autoimmune diabetes

In a recent workshop organized by the JDRF focused on the 'Identification and Utilization of Robust Biomarkers in Type1 Diabetes', leaders in the field of type 1 diabetes (T1D)/autoimmunity and assay technology came together from academia, government and industry to assess the current state of the field, evaluate available resources/technologies and identify gaps that need to be filled for moving the field of T1D research forward. The highlights of this workshop are discussed in this paper, as well as the proposal for a larger, planned consortium effort, incorporating a JDRF Biomarker Core, to foster collaboration and accelerate progress in this critically needed area of T1D research.

Recurrence of autoimmunity in pancreas transplant patients: research update

Type 1 diabetes is an autoimmune disorder leading to loss of pancreatic β-cells and insulin secretion, followed by insulin dependence. Islet and whole pancreas transplantation restore insulin secretion. Pancreas transplantation is often performed together with a kidney transplant in patients with end-stage renal disease. With improved immunosuppression, immunological failures of whole pancreas grafts have become less frequent and are usually categorized as chronic rejection. However, growing evidence indicates that chronic islet autoimmunity may eventually lead to recurrent diabetes, despite immunosuppression to prevent rejection. Thus, islet autoimmunity should be included in the diagnostic work-up of graft failure and ideally should be routinely assessed pretransplant and on follow-up in Type 1 diabetes recipients of pancreas and islet cell transplants. There is a need to develop new treatment regimens that can control autoimmunity, as this may not be effectively suppressed by conventional immunosuppression.

A model for harmonizing flow cytometry in clinical trials

Complexities in sample handling, instrument setup and data analysis are barriers to the effective use of flow cytometry to monitor immunological parameters in clinical trials. The novel use of a central laboratory may help mitigate these issues.

Biologic activity of an idiotype-bearing suppressor T cell factor produced by a long-term T cell hybridoma

Biologic activities and immunochemical characteristics of an azobenzenearsonate- (ABA)specific suppressor T cell factor produced by a longterm T cell hybridoma, F12, were studied. In vivo administration of F12 culture supernatant resulted in the suppression of ABA-specific delayed-type hypersensitivity (DTH) responses and the inhibition of priming for ABA-specific cytotoxic T lymphocyte responses. Moreover, F12 induced a second set of suppressor cells that act in the efferent phase of DTH. The active material in the F12 culture supernatant expressed major cross-reactive idiotypic (CRI) determinants of anti-ABA antibodies of A/J mice and I-J subregion-coded specificities but not express determinants of immunoglobulin constant regions. These results demonstrated that F12 is a functioning hybrid cell line of the first-order suppressor T cell subset.

Biologic activity of an idiotype-bearing suppressor T cell factor produced by a long-term T cell hybridoma

Biologic activities and immunochemical characteristics of an azobenzenearsonate- (ABA)specific suppressor T cell factor produced by a longterm T cell hybridoma, F12, were studied. In vivo administration of F12 culture supernatant resulted in the suppression of ABA-specific delayed-type hypersensitivity (DTH) responses and the inhibition of priming for ABA-specific cytotoxic T lymphocyte responses. Moreover, F12 induced a second set of suppressor cells that act in the efferent phase of DTH. The active material in the F12 culture supernatant expressed major cross-reactive idiotypic (CRI) determinants of anti-ABA antibodies of A/J mice and I-J subregion-coded specificities but not express determinants of immunoglobulin constant regions. These results demonstrated that F12 is a functioning hybrid cell line of the first-order suppressor T cell subset.

Tumor-Associated Blocking Factors: Isolation from Sera of Tumor-Bearing Mice

An isolation and partial purification of tumor-associated blocking factors from the sera of tumor-bearing mice is described. Columns for affinity chromatography were prepared by coupling syngeneic tumor-immune antibodies to Sepharose 4B. Passage of serum through such immunoadsorbent columns removed all blocking activity from tumorbearers' sera; subsequent elution of the absorbent with 3 M NaSCN recovered the activity. The blocking material was further purified on Sephadex G-200. The data provide evidence for the presence of antigen in tumor-associated blocking factors and are compatible with the hypothesis that blocking factors often consist of antigen and antibodies in the form of immune complexes.

Tumor-associated blocking factors: isolation from sera of tumor-bearing mice

An isolation and partial purifications of tumor-associated blocking factors from the sera of tumor-bearing mice is described. Columns for affinity chromatography were prepared by coupling syngeneic tumor-immune antibodies to Sepharose 4B. Passage of serum through such immunoadsorbent columns removed all blocking activity from tumor-bearers' sera; subsequent elution of the absorbent with 3 M NaSCN recovered the activity. The blocking material was further purified on Sephadex G-200. The data provide evidence for the presence of antigen in tumor-associated blocking factors and are compatible with the hypothesis that blocking factors often consist of antigen and antibodies in the form of immune complexes.