Presented at:
XXIIth International Congress of Immunology, Montreal, QC, Canada, July 18-23, 2004
Abstract #2778
Marked Differences in T Cell Reactivity in Recently Diagnosed Type 1 Diabetes Patients Versus Controls
Brooks-Worrell BM, Dosch HM, Herold K, Seyfert V, Greenbaum CJ, Gitelman SE, Palmer JP
Department of Medicine/Metabolism, Endocrinology and Nutrition, University of Washington/Puget Sound Health Care System, Seattle, WA, USA; Pediatrics/Immunology, University of Toronto/The Hospital for Sick Children, Toronto, ON, Canada; Clinical Medicine, Columbia University Hospital, New York, NY, USA; Diabetes Research Unit, Benaroya Research Institute, Seattle, WA, USA; Clinical Pediatrics, University of California at San Francisco, San Francisco, CA, USA.
Although antibodies to islet antigens are useful as markers for Type 1 diabetes (T1DM), the disease is T-cell mediated. In prior blinded workshops, various T-cell assays using peripheral blood had difficulty distinguishing responses of normal controls versus type 1 diabetes patients. To test their ability to distinguish normal controls from type 1 diabetes patients, two proliferative assays (developed in Seattle and Toronto respectively) were tested in a blinded workshop sponsored by the Immune Tolerance Network (ITN).
Blood samples were obtained from normal controls and recently diagnosed young type 1 diabetes patients and shipped overnight, without freezing, to Seattle and Toronto. The T cell assay performed in Seattle (cellular immunoblotting) utilizes nitrocellulose particles containing human islet proteins to stimulate the isolated peripheral blood mononuclear cells (PBMCs) whereas, the Toronto assay utilizes 8-14 purified soluble islet proteins/peptides. Both assays measure peripheral blood mononuclear cell proliferative responses to the proteins. Masked blood samples from 17 type 1 diabetes patients and 33 normal controls were shipped to Seattle. Of these samples, the Seattle assay correctly identified 16/17 (94%) type 1 diabetes patients and 27/33 (82%) of controls (p<0.0001). Masked blood samples from 18 type 1 diabetes patients and 26 normal controls were evaluated in Toronto. For the Type 1 patients, the Toronto assay found 10/18 (65%) positive. Five type 1 samples were flagged for rerun. For the normal subjects, the Toronto assay found 24/26 (92%) negative (p<0.001).
In conclusion, two separate and distinct T cell proliferation assays have correctly distinguished type 1 diabetes patients versus controls in a blinded workshop. These results demonstrate that sufficient islet antigen reactive T-cells circulate in type 1 diabetes patients to be detected in the peripheral blood. Moreover, these results also suggest that measurements of islet reactive T-cells may be useful in further investigating human T1DM and in monitoring interventions aimed at altering the disease process.