Antigenic properties of the cell wall and other fractions of the yeast form of Histoplasma capsulatum.

Pine, Leo (Communicable Disease Center, Atlanta, Ga.), Clarence J. Boone, and Dave McLaughlin. Antigenic properties of the cell wall and other fractions of the yeast form of Histoplasma capsulatum. J. Bacteriol. 91:2158-2168. 1966.-Yeast-form cells of Histoplasma capsulatum were fractionated in an attempt to obtain complement-fixing antigens with greater specificity than those of the currently used whole yeast form. No specific fraction was isolated. Rupture of the whole cell produced soluble and insoluble highly antigenic fractions. The soluble fractions rapidly lost antigenicity. Marked reduction of activity of some particulate fractions was also observed. The purified cell wall, stripped of its protein components, was antigenic, relatively stable, and demonstrated low cross-reactivity with heterologous sera. All fractions cross-reacted with sera from cases of North American blastomycosis to a greater degree than did the whole yeast-form antigen of H. capsulatum. The production of certain cellular fractions varied with the strains used. In complement-fixation tests, insignificant differences in specificity and antigenicity were found with whole-cell antigens from 13 H. capsulatum strains as well as with purified cell wall fractions prepared from 2 of these strains.