Antigen arrays for antibody profiling
Introduction
Production of high-affinity, high-avidity antibodies is a hallmark of many autoimmune and infectious diseases. Further, detection of antibodies represents a mainstay in laboratory diagnostics for multiple autoimmune and infectious diseases. For example, detection of blood autoantibodies targeting immunoglobulin (rheumatoid factor) and/or citrullinated peptides contributes to the diagnosis of rheumatoid arthritis (RA) [1], whereas detection of autoantibodies targeting nuclear antigens (anti-nuclear antibodies [ANAs]) suggests the diagnosis of systemic lupus erythematosus (SLE) [2]. Microbial infections, including infections with Epstein Barr virus (EBV), hepatitis B virus (HBV) and human immunodeficiency virus (HIV), can be diagnosed by detection of host antibody responses against the microbe.
Antigen arrays represent a powerful approach for large-scale characterization of antibody responses against candidate antigens. Antigen arrays provide the ability to identify and characterize antibodies targeting known and novel antigens, and to identify antibody profiles that provide insights into the pathogenesis of disease and provide diagnostic and prognostic utility. This review provides an overview of antigen arrays and highlights several recent applications of antigen array technologies in autoimmune disease, cancer and infectious disease.
Section snippets
Antigen array technologies
A variety of antigen array technologies for antibody profiling have been developed. Proteins and peptides representing candidate autoantigens can be attached to planar surfaces in ordered arrays to survey autoantibody binding [3, 4, 5]. Antibody characterization can also be performed using arrays of in situ synthesized peptides generated by photolithography [6] or synthesized on pins [7, 8]. Arrays of mammalian cells [9] or yeast [10] expressing defined cDNAs, and arrays produced using in situ
Autoimmune disease
Autoimmune diseases affect an estimated 3% of the world population, and arise from aberrant activation of immune responses to target tissues or cells within the body. Examples of autoimmune diseases include RA, in which the synovial joints are targeted; autoimmune type I diabetes, in which β cells in the pancreatic islets of Langerhans are targeted; and SLE, in which a variety of nuclear components are targeted.
Despite knowledge of the specific tissues and cells targeted and the involvement of
Strategies for antigen discovery
A major limitation for most antigen array analyses is that the utilized antigens are limited to proteins and other biomolecules that are known to represent candidate targets, and for which synthetic or purified preparations are available. Further, for many autoimmune, malignant and infectious diseases the antigens remain poorly characterized. It is estimated that an individual cell expresses approximately 10 000 proteins [33]. The ability to produce or purify the constellation of polypeptide
Antibody and cytokine profiling identify molecular subsets of RA
We developed ‘arthritis arrays’ containing the putative autoantigens in RA. Arthritis microarrays revealed targeting of citrullinated proteins in a subpopulation of RA patients possessing clinical and laboratory features predictive of more severe arthritis [37•] (Figure 1). We also performed multiplex analysis of blood cytokines in RA using a bead array. Integration of blood autoantibody and cytokine profiles revealed distinct subtypes of RA (W Hueber and W Robinson, unpublished data). We
Conclusions
Major progress is being made towards developing and refining antigen array technologies for profiling antibody responses in autoimmune, malignant and infectious diseases. Profiles of antibody reactivities are anticipated to provide superior diagnostic and predictive value as compared to individual specificities. Significant work remains to elucidate and define the antigen targets in a variety of autoimmune, infectious and malignant diseases. Major challenges also remain in the refinement,
References and recommended reading
Papers of particular interest, published within the annual period of review, have been highlighted as:
• of special interest
•• of outstanding interest
Acknowledgements
The author thanks Drs L Steinman and PJ Utz, as well as Drs W Hueber, J Kanter and other members of the Robinson, Steinman and Utz laboratories. This work was supported by NIH K08 AR02133, NIH NHLBI contract N01 HV 28183, and a Department of Veterans Affairs Merit Award to WHR and NIH P30 DK56339 to the Stanford Digestive Disease Center
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