Emergence of Protein A as a 'Universal Immunoadsorbent' In Immunoassays: A Novel Diagnostic Platform

• Published in: Indian journal of clinical biochemistry Vol. 36; no. S1; p. S67
• Main Authors: Gholve, Chandrakala, Kulkami, Savita
• Format: Journal Article
• Language: English
• Published: Springer 24.05.2022
• Subjects: Autoimmunity; Monoclonal antibodies; Recombinant proteins; Tracers (Biology)
• ISSN: 0970-1915; 0974-0422

Protein A, derived from cell wall of Staphylococcus aureus, has remarkable ability to bind with constant (Fc) portion of immunoglobulin molecules from several different species. So far in immunoassays, Protein A has been used as a separating reagent in the separation of bound and free ligand and as a "universal tracer". For the first time, we have described a unique and novel assay format that displays the use of recombinant Protein A coupled with magnetic particles or polystyrene tubes as a solid phase immunoadsorbent in the development of assays for TPO autoantibodies using radiolabelled recombinant TPO as the specific tracer. Sensitivity, specificity, high precision and automation of these in-house developed radioassays make them perfectly suitable for routine clinical investigations. Conventionally, different kits for different autoantibodies demand specific purified antigens or monoclonal antibodies coated on various solid phases. Whereas our assay which proposes the use of 'universal immunocapture' format; for detection of an array of autoantibodies; would help in reducing overall time and cost during the production of kits. This format also has an added advantage of oriented conjugation of the antibody thereby preserving antibody activity. In conclusion, the novelty of the assay mentioned highlights the format selected and therefore can be adopted in the development of isotopic as well as non-isotopic assays (using alternative labels like fluorophores, chemiluminescent, enzyme, etc. for laboratories that pose problems in the handling of radioisotopes), for the measurement of autoantibodies. Finally, the proposed format both in its isotopic and non-isotopic formats has the potential to revolutionize immunodiagnostics in the future.