Coons, Albert

Albert H. Coons (Fig. 1.2) was the first who attached a fluorescent dye (fluorescein isocyanate) to an antibody and used this antibody to localize its respective antigen in a tissue section. The concept of putting a visible label on an antibody molecule appeared both bold and original. His initial results were described in two brief papers in the early 1940s (Coons et al. 1941,1942), but the research was halted while he joined the army and spent the next 4 years in the South Pacific. His later studies (Coons and Kaplan 1950) contributed immensely to the use of the fluorescent antibody method in a wide variety of experimental settings. In our time, the use of antibodies to detect and localize individual or multiple antigens in situ has developed into a powerful research tool in almost every field of biomedical research (http //books.nap.edu/html/biomems/acoons.pdf). 

Fig. 1.2 Albert H. Coons (Courtesy of the Harvard Medical School Countway Library)...

Fluorophores were introduced to fluorescence microscopy in the early twentieth century, but did not see widespread use until the early 1940s when Albert Coons developed a technique for labeling antibodies with fluorescent dyes, thus giving birth to the field of immunofluorescence (http //www.olympusconfocal.com/ theory/fluorophoresintro.html). By attaching different fluorophores to different antibodies, the distribution of two or more antigens can be determined simultaneously in the tissue section and, in contrast to brightfield microscopy, even in the same cells and in the same cell structures (see Chap. 8). 

Albert H. Coons was the first to attach a fluorescent dye (fluorescein isocyanate) to an antibody and to use this antibody to localize its respective antigen in a tissue section. Fluorescein, one of the most popular fluorochromes ever designed, has enjoyed extensive application in immunofluorescence labeling. For many years, classical fluorescent probes such as FITC or Texas red (TR) have been successfully utilized in fluorescence microscopy. In recent decades, brighter and more stable fluorochromes have continually been developed (see Table 14.1). Marketed by a number of distributors, cyanine dyes, Cy2, Cy3, Cy5, Cy7, feature enhanced water solubility and photostability as well as a higher fluorescence emission intensity as compared to many of the traditional dyes, such as FITC or TR. 

The pioneering immunofluorescence studies of Albert Coons and colleagues in the 1940s and 1950s (reviewed in ref. 11) established the effectiveness of fluorescein for immunofluorescence microscopy. The green emission of fluorescein isothiocyanate (FITC) was shown to provide a strong signal, well separated from blue cellular autofluorescence. Continued wide use of fluorescein attests to its utility. 

This book is intended for scientists who are working on research animals and cultured cells. The procedures described here give the best results with the easiest methods. Note that many older procedures and reagents are still used today, but they give less than ideal results. For example, the fluorophore FITC was the first fluorophore used for immunocytochemistry by Albert Coons in 1942, when he invented this field. Since then, three new generations of fluorescent compounds (Chapter 6, Labels) with improved photobleaching properties have evolved making FITC of historical interest for immunocytochemistry. 

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