CHARACTERIZATION OF PARASITE ANTIGENS ... - PAHO/WHO

e*
*e.~~~~~~~~~~~~~ 8
calcium. This antigen on chemical analysis contained protein
and lipid in a ratio of 2.5:1. The purified antigen was free
of carbohydrate and after acid hydrolysis was negative for
purines and: pyrimidines. Since Cohn's method for isolation of
fraction III-0 was employed, Sleeman suggested the antigen may
be a beta-lipoprotein or a "'lipo-poor euglobulin."
An antigenic polysaccharide material was extracted from
cercariae and eggs of S. mansoní by Smithers and Williamson
(107, 127). Extensive analysis indicated that the antigen
was a "glucan polysaccharide of glycogen-like properties."
A similar antigen was prepared for the intradermal test by
Pellegrino et al. (92) from cercariae of S. mansoni. These
workers concluded from their studies that chemical moieties
other than carbohydrates were active in the schistosome skin
test. Kagan and Goodchild (55) evaluated the polysaccharide
content of a series of antigens that were adjusted to similar
nitrogen content and gave similar reactivity in the skin (wheal
areas in 25 infected individuals were not significantly different).
The carbohydrate content did not correlate with the intradermal
activity. Gazzinelli et al. (38) fractionated cercarial extract
in a DEAE-Sephadex A-50 column and found the most active fraction
in the intradermal test to be free of polysaccharide.