DIFFERENTIAL RELEASE OF AN IMMUNODOMINANT 65-KDA MANNOPROTEIN ANTIGENFROM YEAST AND MYCELIAL FORMS OF CANDIDA-ALBICANS

The release of mannoprotein (MP) antigen from Candida albicans grown a t 28 degrees C (yeast form) or 37 degrees C (mycelial form), and the a bility of each released material to stimulate a cell-mediated immune ( CMI) response by human lymphocytes in vitro, were studied. Overall, th e mycelial cells released more MP per unit of dry mass increase and th e released material was relatively enriched with MP constituents of lo wer molecular mass with respect to the material released from yeast ce lls. Moreover, the mycelial MP contained a 65 kDa component (MP65) whi ch was the largely predominant MP recognized by a rabbit anti-mycelium antiserum. When peripheral blood mononuclear cells from normal human subjects were stimulated in vitro with graded amounts of yeast or myce lial MP, the latter was about one order of magnitude more potent than the former in inducing lymphocyte proliferation. Following MP separati on by gel permeation chromatography, an appreciable CMI response was s timulated only by the MP65-containing MP fractions, and to a degree ap parently related to the amount of MP65 itself. Altogether, these data confirm our previous findings about the MP65 antigen as a major target of CMI response to C. albicans, and demonstrate that this antigen is released predominantly by the mycelial cells of the fungus in vitro.