A number of skin test antigens prepared by several methods from cercariae and adults of Schistosoma mansoni were analyzed for polysaccharide content by the anthrone method and nitrogen content by Nessler and micro-Kjeldahl methods. No correlation between nitrogen and polysaccharide content of the antigens was observed. Antigens prepared in different laboratories and adjusted to approximately similar nitrogen content gave comparable wheal areas when injected into the skin. The polysaccharide content of these antigens varied from 23 to 114 gamma per ml. It was concluded that polysaccharide content was an unreliable indicator of the in vivo activity of these skin test antigens.
United States Public Health Service, Communicable Disease Center, Atlanta, Georgia.
Department of Biology, Emory University, Atlanta, Georgia.