TEMPERATURE-DEPENDENT SURFACE EXPRESSION OF THE BETA-2-INTEGRIN ANALOG OF CANDIDA-ALBICANS AND ITS ROLE IN ADHESION TO THE HUMAN ENDOTHELIUM

Candida albicans has become one of the most important pathogens in int ensive care units. Adherence of C. albicans to the vascular endotheliu m is believed to represent a critical step in the pathogenesis of diss eminated candidiasis and may involve molecules analogous to human beta (2)-integrins such as the complement receptor 3 (CR3) analogue of C. a lbicans (C.a.-CR3). Its expression was detected by a sensitive resetti ng assay when Candida was present in its hyphal form but not in its ye ast form, the latter being generally considered to be less pathogenic. However, the presence of hyphae alone was not sufficient: C.a.-CR3 ex pression was found to be-temperature-dependent for 4 (out of 10) clini cal isolates. Two rosetted better after growth at 30 degrees C, the ot her 2 after growth at 37 degrees C. This temperature dependence was mo st pronounced for 1 laboratory strain: C.a.-CR3 expression was best at 30 degrees C and markedly decreased with increasing temperatures. At 37 degrees C no rosettes were detected at all. Modifications of the cu lture conditions (e.g. agitation, pH) exerted a marked influence on th e morphology of this strain but always allowed rosette formation once hyphae were formed at 30 degrees C. However, none of these modificatio ns was able to induce rosettes at 37 degrees C. Adhesion of C. albican s isolates to an endothelial cell line was also temperature-dependent but not strongly correlated with C.a.-CR3 expression. Most strains exh ibited a better adherence when grown at 30 degrees C. This finding may be of importance for exogenous infections, with Candida spp. invading the body from the outside, where the temperature is usually lower tha n the physiological body temperature.