Comparative Studies on Tree Pollen Allergens

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Abstract
Visualization by autoradiography of specific IgE binding in crossed radioimmunoelectrophoresis (CRIE) and other 125I-immunoautoradiography (IAR) techniques is done in two different ways; either by traditional direct autoradiography (D-ARG), where the film is exposed to the 125I-anti-IgE incubated sample at room temperature, or by indirect autoradiography (ID-ARG), applying intensifying screen, low-temperature exposure and, eventually, pre-exposure. This study confirmed that D-ARG provided the benefits of simplicity and better image resolution with the disadvantage of prolonged exposure periods. ID-ARG better image resolution with the disadvantage of prolonged exposure periods. ID-ARG reduced the exposures needed to produce film range image densities of 0.01 and 0.1 A540 nm (i.e. autoradiographic sensitivity (AR.sigma.) and autoradiographic speed (ARs)) to 1/18 and 1/55 respectively of the corresponding exposures in D-ARG. The lowest detection limits for 125I in 24 h were 1.2 cpm mm-2 with the indirect and 6.8 cpm mm-2 with the direct systems investigated. The major drawbacks of ID-ARG were inferior image resolution and higher background levels, especially when pre-exposure was included.