Updates in Immunoassays: Introduction

Deborah Josko

doi:10.29074/ascls.25.3.170

This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.

Deborah Josko, Ph.D. MLT (ASCP) M,SM⇑
1. Department of Clinical Laboratory Sciences, Medical Laboratory Science Program, University of Medicine and Dentistry of New Jersey, Scotch Plains, NJ

Address for Correspondence: Deborah Josko, Ph.D. MLT(ASCP)M, SM, Department of Clinical Laboratory Sciences, Medical Laboratory Science Program, University of Medicine and Dentistry of New Jersey, 1776 Raritan Road, Scotch Plains, NJ 07076. (908) 889-2422. joskotda{at}umdnj.edu

Discuss the evolution and development of immunoassays.
Explain the principle of various immunoassays used in diagnosis.
List emerging methodologies in the area of immunological assays.
Describe the importance of immunoassay testing in the clinical laboratory.

Extract

The immune system is one of the most intricate and complex systems of the human body. The cascade of events that occurs at both the cellular and molecular level from the moment foreign matter enters the body is astounding. Once antibodies are synthesized by plasma cells in response to the invading entity, medical laboratory professionals have the ability to measure and identify the type of antibody present by a variety of immunological assays. Detection methods range from rapid latex agglutination assays to enzyme, fluorescent and chemiluminescent assays that can measure both IgM and IgG levels qualitatively and quantitatively.

Immunoassays have evolved considerably when compared to some of the earlier methods of identifying antigen/antibody complex formation. The Ouchterlony double immunodiffusion assay developed in the 1940s by Swedish immunologist Örjan Ouchterlony¹ is one of the older methods where both antigen and antibody diffuse through a semi-solid gel independently of each other resulting in a precipitation line if the specific antigen/antibody complex is formed (identity pattern).² This assay can take up to 48 hours to completely diffuse and render a positive result. To improve turn-around times, assays were designed using electrical currents during the diffusion process to speed up the reaction time. One method developed by Grabar and Williams in 1953 was the rocket immunoelectrophoresis technique.³ In this assay, antigen is added to an appropriate medium, then subjected to an electrical current where protein fractions are separated according to size. Antiserum is then placed in a trough cut into the gel and allowed…

ABBREVIATIONS: ANA - anti-nuclear antibody; CBC - complete blood count; CDC - Centers for Disease Control and Prevention; CLIA - chemiluminescent immunoassay; CMV - cytomegalovirus; CRP - C-reactive protein; DFA - direct fluorescent antibody; EIA - enzyme immunoassay; ELFA - enzyme-linked fluorescent assay; ELISA - enzyme-linked immunosorbent assay; FIA - fluorescent immunoassay; HCG - human chorionic gonadotropin; HIV - human immunodeficiency virus; IFA - indirect fluorescent assay; IgG - immunoglobulin G; IgM – immunoglobulin M; RSV - respiratory syncytial virus.