Comparative study between the Methods of double diffusion in gel and radical immunodiffusion of IGA and IGM in coord blood

Abstract

In order to find a simple and low cost method that could be used for routine determination of IgA and IgM in cord blood for screening of congenital infections, we studied comparatively the method of Double Diffusion in Gel Ouchterlony (DD) with the method of Radial Immunodiffusion-Mancini (RID), commonly utilized. Cord blood samples were obtained from 85 newborns and IgA and IgM were determined concomitantly by the two methods. The preliminary results showed 11 cases where the determinations of IgM of IgA were negative by RID but positive by DD with high titles. A repeated dosage by RID with serum diluted by half or using immunodiffusion plates for higher concentrations, showed positiveness for these inrnunoglobulins, proving therefore, the importance of double diffusion in detecting falsely negative results obtained by the radial immunodiffusion method. In 6% of the cases, IgM values obtained by RID were higher than 20 mg/dl were detected from title 1/2 up, corresponding to 31.76% of the studied population. For screening of congenital infections, IgM titles equal or superior to 1/2 by DD should be complemented quantitatively by RID. Statistic analyses showed a parallelism between these two methods. Taking into account its low cost and simplicity, the method of double of diffusion in gel is recomended for the routine determination og IgA and IgM in cord blood.