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Biotechnology and Bioprocess Engineering 16: 1248-1253 (2011) DOI 10.1007/s12257-011-0106-7
RESEARCH PAPER
Immunostick Assay for Medical Diagnosis of Rheumatoid Arthritis
Hyuk Ko, Eun-Hang Lee, Byoung-Jin Jeon, Hye-Jin Choi, Min-Jung Kang, and Jae-Chul Pyun
Received: 14 March 2011 / Revised: 13 June 2011 / Accepted: 28 June 2011 The Korean Society for Biotechnology and Bioengineering and Springer 2011
Abstract An immunoassay based on stick-type solid support (immunostick assay) was developed. To demonstrate the medical diagnosis of rheumatoid arthritis (RA), cyclic-citrullinated peptide (CCP), one of specific antigens against RA autoantibodies, was immobilized on the surface of the immunostick, and a color index table was prepared for the determination of CCP-positivity of the test sera. The positivity of RA-positive (n = 31) and RA-negative (n =20) sera was tested using the immunostick assay and a conventional enzyme-linked immunosorbent assay (ELISA). The statistical agreement of the test results from both methods was analyzed using inter-rater coefficient kappa and Bland-Altman test. The immunostick assay with a color index table was determined to have a high statistical correlation to the conventional ELISA method.
Keywords: immunoassay, immunostick, cyclic-citrullinated peptide, rheumatoid arthritis
1. Introduction
Immunoassays have been utilized to detect a target analyte in a complex sample matrix by using the highly specific interaction between antigens and antibodies [1]. Various types of immunoassays have been developed; most of the methods are especially dependent on the different solid phase materials and their shapes, such as microplates, microparticles, and micromembranes. Additionally, different
labels and end-points that are used include radioactive, fluorescent, enzymatic, or colored particles [2]. Among the various immunoassay methods, the enzyme-linked immunosorbent assay (ELISA) capable of examining many samples simultaneously in 96 or 386-well microplates is one of the most commonly used immunoassay methods. Presently, an immunoassay suitable for a small number of samples was developed based on a previously-reported stick-type of solid support designated as an immunostick assay [3,4]. This method can be easily used for the manual testing of a small number of samples within 1 h. The test results are displayed by a chromogenic reaction on the stick surface the positivity of the test is determined using a color index table. The immunostick can be used for qualitative and quantitative immunoassays without the need for instruments such as an optical...