New technologies for autoimmune disease monitoring

Abstract

Purpose of review: This article will review new technologies used to characterize the immune phenotype of cells and serum for potential use in studies of autoimmunity.

Recent findings: One area of recent development in studies of immune phenotyping is the contrast between cells of the immune system at rest and following activation. This simply involves comparing these cells at rest and following ligand-induced activation and measuring signaling system activation (phosphoepitope identification) or intracellular cytokine production or activation-induced gene expression. Preliminary data using these techniques have begun to identify signatures of disease (biomarkers) that are only seen when using these activation-induced assays. One of the most exciting new technologies, cytometry by time-of-flight mass spectrometry, couples a flow cytometer to a mass spectrometer, allowing many more parameters to be analyzed per cell, and without spillover between assay reagents, compared to conventional optical flow cytometry (heavy ions, mass, replaces fluorophore readout). Another new technology to analyze soluble proteins, bead-based immunoassays, can simultaneously measure up to 75 soluble analytes in a multiplexed array. Other technologies provide similar innovations in terms of analytical content, throughput, and miniaturization.

Summary: We believe that new cellular genomic and protein-based technologies can provide key insights into autoimmune disease pathogenesis, progression, and therapy, and that these assays need to be applied in a systematic way to samples from patients with autoimmune diseases.

Figure 1. Cytometry by time-of-flight mass spectrometry principle

(a) Principle of cytometry by time-of-flight mass spectrometry: antibody labeling with heavy metal isotopes, binding of labeled antibodies to cells, and conversion of labeled cells to plasma for quantitation of heavy isotopes by time-of-flight mass spectrometry. (b) Limitation of the visible spectrum is shown by the overlap in emission spectra of eight common fluorescent dyes. (c) By contrast, elemental isotopes of different mass are exquisitely separated by time-of-flight mass spectrometry, allowing many more labeled antibodies to be combined, without interference between labels.