Radial immunodiffusion quantitation of proteins by an antibody overlay technique

Abstract

An economical alternative to the determination of proteins by single radial diffusion in antibody-containing agarose gel is described. The method, which is the equivalent of the above, consists of allowing the sample to diffuse into the gel layer, overlaying of the sample well with antibody-impregnated filter paper (10.2 μl/cm 2), incubation in a moist chamber for 20 hr, determination of precipitin zone size, and plotting concentration vs precipitin zone size. The plot was a straight line equivalent to that obtained by Fahey and McKelvey ( J. Immunol. 94, 84–90, 1965). The average coefficient of variation was 1.6%.