ABSTRACT
Objective To comparatively analyze the advantages and disadvantages between a double immune-diffusion assay and a rate nephelometer analysis for the detection of antigen activity of pneu -mococcal capsular polysaccharides .Methods The antigen activity of pneumococcal capsular polysaccharides of serotypes 1,6B,9V,10A,14 and 19A from four manufacturers and ATCC were analyzed by a double im-mune-diffusion assay and a rate nephelometer analysis , respectively .The effects of antiserum samples and gain values on the rate response value were evaluated .Results The sample 4 of type 9V showed no antigeni-city with a rate response value similar to that of negative control as indicated by both tests .However ,the pre-cipitation lines and the rate response values presented by other polysaccharide samples differed in a wide range.Results of the rate nephelometer analysis were not affected by the anti -serum samples from different sources and the gain values .Conclusion The rate nephelometer analysis could quantitatively analyze the antigen activity of pneumococcal capsular polysaccharides .