Abstract
The test depends upon the precipitation of a colloidal gold sol by an electrolyte (sodium chloride) in the presence of serum containing varying amounts of immune bodies specific for poliomyelitis.
Preliminary experiments were made with normal and immune monkey and normal and poliomyelitic human serums in the presence of varying dilutions of Kolmer's cholesterinized antigen and different concentrations of sodium chloride. Other antigens such as plain and cholesterinized extracts of normal rabbit and sheep brain were studied also.
In a manner similar to that described by Mishulow and Krumwiede, 1 Sanderson and Yoe, 2 for the determination of toxicity of diphtheria toxin, and recently by Jungeblut 3 in poliomyelitis, an investigation was made of the possible effect of 1% gold chloride. The results were not specific or consistent and the use of antigens and gold chloride was discarded. A peculiar color change ranging from lilac to deep purple was observed in certain tubes that contained immune serum in the presence of this reagent, however, and the idea of a color reaction suggested itself. Inasmuch as the antigens and gold chloride had seemed to possess no particular merit in such a test, Lange's colloidal gold was used.
The method adopted finally utilized colloidal gold, sodium chloride (0.4%) and serum in proportions that were found most effective and clear cut in numerous preliminary determinations. Dilutions of serum were prepared in series in an attempt to detect quantitative differences. Readings were made after 12-16 hours. With cholesterinized sodium chloride, however, results could be read easily after 3 hours at room temperature (22-25°C.).
Composite experiments were repeated with uniform agreement and the results appeared decisive. Poliomyelitic serum from convalescent adult and juvenile patients and immune monkeys consistently produced a rose-colored or violet precipitate with a supernatant fluid graded from clear and colorless to light salmon pink and finally the negative rose color of the control.
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