Quantitative estimation of IgA in rats: a comparison of two methods.

Two methods for estimating IgA in body fluids of rats were devised and tested for their accuracy and reliability. Specifically purified monomeric and polymeric IgA was prepared so that results obtained could be properly assessed. The two systems tried were prepared so that results obtained could be properly assessed. The two systems tried were rocket immunoelectrophoresis, carried out after reduction of samples with dithiothreitol and using monomeric IgA as standard, and a radioimmunoassay utilising a double antibody precipitation method and polymeric IgA as standard. Rocket immunoelectrophoresis was found generally unsuitable for IgA estimation: the reduction methods employed were found to be unreliable or unsuitable for some samples, and the estimation of IgA in bile by this method was further complicated by the presence of IgA fragments. The radioimmunoassay system, however, could be used to estimate IgA to a lower limit of 1 microgram/ml, and accurate results could be obtained almost irrespective of the molecular weights of the IgA in the sample.