Enzyme-linked immunosorbent assay for the epidermal growth factor receptor

An enzyme-linked immunosorbent assay (ELISA) for the epidermal growth factor (EGF) receptor was developed using three different antibody preparations, one of which is commercially available. Using one of the antisera (986), the assay could detect as few as 200 × 10⁶ receptors. This is equal to 0.332 fmol. This sensitivity means that a minimum of 100 A-431 cells (human carcinoma) or 5,000 normal cells are needed to quantitate the number of EGF receptors. Two of the antisera (986 and 451) recognized EGF receptors from placental tissue. EGF receptors from as little as 667 ng of placental membrane protein were detectable. The assay is highly species specific, with the sensitivity for the EGF receptor from different species dependent on the antiserum used. The commercial antibody, 29.1, had especially strong reactivity against pig and dog EGF receptors. An ELISA using this antibody had the capacity to detect the number of EGF receptors in 10 μg of liver membrane protein. The assay is sensitive to receptor conformation. The binding of antisera 986 and 451 to 1% sodium dodecyl sulfate (SDS)-denatured receptor was reduced. The binding of antibody 29.1 was impaired by the presence of 1% Triton X-100 but not the same levels of Tween-20 or SDS. In addition to being a sensitive technique for the quantitation of the EGF receptor, this assay is very rapid, taking a total of 4 h. The microtiter dish format also allows hundreds of samples to be assayed at once. By using the appropriate antiserum and standards, the EGF receptor can be quantitated in tissues from humans, dogs, pigs, and mice.     

Genetic analysis of cell adhesion

Cellular adhesion is what keeps cells together in multicellular organisms. Cells adhere to each other, to extracellular matrices, and to the substratum. Biochemical analyses of these processes have suggested some of the types of surface molecules which may be involved, but definitive evidence must rely on effective reconstruction of functional membranes or genetic alteration of the pertinent genes. Together these approaches may give us a better understanding of how cells sort out and form tissues during development.