Cell walls of normal and lysozyme-damaged blastoconidia of Candida albicans: localization of surface factor 4 antigen and vicinal-glycol staining

The fungicidal effect of lysozyme on Candida albicans involves ultrastructural modifications previously described (G. Marquis, S. Montplaisir, S. Garzon, H. Strykowski, and P. Auger, Lab. Invest. 46:627-636, 1982). To further define the action of lysozyme on the yeast cell wall, we used the following: (i) the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) method to highlight vicinal-glycol-reactive sites of complex carbohydrates; (ii) a monospecific antiserum and a protein A-gold complex to study the expression of surface factor 4, a major Candida antigen; and (iii) the periodic acid-silver methenamine method to stain cell wall glycoproteins. All Candida cells were found to express surface factor 4 antigen. In normal blastoconidia, surface factor 4 was located in a glycoprotein-rich cell wall layer, underneath radially oriented bundles of filaments which form the outermost wall layer. In lysozyme-treated blastoconidia, this glycoprotein-rich layer was lost and the regular brushlike organization of the outer fibrillogranular layer was disrupted. PA-TCH-SP staining and localization of surface factor 4 antigen demonstrated an altered arrangement of bundles of filaments in the outer wall layers of blastoconidia which were morphologically intact but had abnormal cell wall appearance. Next, there was a reduction in thickness of the outer layer and the expression of surface factor 4 antigen was limited to the cytoplasmic membrane area. Later on, the cell wall was almost uniformly highlighted by PA-TCH-SP staining. These data evinced a highly plastic architecture of the cell wall in C. albicans.