Critical parameters in blood processing for T-cell assays: validation on ELISpot and tetramer platforms.

Assays detecting antigen (Ag)-specific T-cell responses in immune-mediated processes are increasingly employed to understand disease pathogenesis and immune staging. The quantity and quality of starting peripheral blood mononuclear cell (PBMC) preparations are important factors in the performance of such assays. We therefore compared final PBMC yield and function by modifying parameters at the blood drawing, storage and processing steps.

The frequency and immunodominance of islet-specific CD8+ T-cell responses change after type 1 diabetes diagnosis and treatment.

Objective: Islet-reactive CD8(+) T-cells play a key role in the pathogenesis of type 1 diabetes in the NOD mouse. The predominant T-cell specificities change over time, but whether similar shifts also occur after clinical diagnosis and insulin treatment in type 1 diabetic patients is unknown.

Research Design And Methods: We took advantage of a recently validated islet-specific CD8(+) T-cell gamma-interferon enzyme-linked immunospot (ISL8Spot) assay to follow responses against preproinsulin (PPI), GAD, insulinoma-associated protein 2 (IA-2), and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP) epitopes in 15 HLA-A2(+) adult type 1 diabetic patients close to diagnosis and at a second time point 7-16 months later.

Serum-free culture medium and IL-7 costimulation increase the sensitivity of ELISpot detection.

The identification of parameters maximizing detection sensitivity in ELISpot assays is important to transfer this technology into the clinical setting for identifying rare Ag-specific CD8(+) T cells. We have therefore considered human IFN-gamma CD8(+) T cell responses against viral epitopes to analyze different variables which could be critical during the epitope-specific stimulation period. Two parameters were found to greatly enhance detection sensitivity (i.