VARIABILITY IN EXPRESSION OF ANTIGENS RESPONSIBLE FOR SEROTYPE SPECIFICITY IN CANDIDA-ALBICANS

The monoclonal antibody (mAb) B9E, which reacts with a cell wall surfa ce determinant of Candida albicans serotype A, and a polyclonal monosp ecific antiserum against the antigen 6 (IF6) were used to investigate the expression of the antigens responsible for the serotype specificit y in C. albicans under different growth conditions. By indirect immuno fluorescence, both antibodies reacted with the cell wall surface of se rotype A yeast cells and germ tubes grown in vitro but no reactivity w as observed with serotype B yeast cells. In some cases, only a weak re activity restricted to a zone close to the parent yeast cell was obser ved in serotype B germ tubes stained with mAb B9E. Both antibodies rea cted strongly with yeast cells and germ tubes present in kidney absces ses from rabbits infected with both serotypes, but only serotype A yea st cells and germ tubes present in smears from patients with vulvovagi nal candidiasis reacted with B9E and IF6 antibodies. The expression of antigens reactive with both antibodies was modulated by the ph of the environment in which the fungus was grown. Both antibodies showed a s imilar pattern of reactivity when studied with a spectrofluorometer. S erotype A yeast cells showed maximum reactivity when cells were grown on Sabouraud dextrose broth supplemented with yeast extract at ph 4.6. The lowest reactivity was observed in cells grown at ph 2.0. Converse ly, the reactivity of serotype B yeast cells increased at alkaline ph values, the highest being in cells grown at ph values of 7.2 and 9.5. A precise use of the methods employed in studies on C. albicans seroty pe prevalence will be important to avoid the influence of ph on the ex pression of antigens conferring serotype specificity.