CANDIDA-ALBICANS EXPRESSES A FIBRONECTIN RECEPTOR ANTIGENICALLY RELATED TO ALPHA-5-BETA-1 INTEGRIN

Cell adhesion molecules, by regulating host-micro-organism interaction , play a major role in the pathogenesis of infectious diseases. The pr esent study was undertaken to investigate the expression of the fibron ectin (FN) receptor prototype. alpha 5 beta 1 integrin. on Candida alb icans and its involvement in the adhesion to FN. By immunofluorescence and fluorescence activated cell sorter (FACS) analysis, several monoc lonal antibodies (mAbs) directed against human alpha 5 or beta 1 integ rin subunits, or two different antisera to FN receptor positively stai ned C. albicans yeast and germ tube phases, this immunoreactivity incr easing upon germ tube transition. Twenty-five to thirty per cent of [H -3]glucose-labelled Candida yeasts specifically adhered to FN and this adhesion was increased upon germ tube transition. C. albicans yeast a nd germ tube forms bound to an RGD-containing 120 kDa tryptic fragment of FN and adhesion to FN was markedly inhibited by GRGDSP, but not GR GESP peptides. Moreover, binding of both C. albicans phases to FN was strongly inhibited by anti-alpha 5 SAM-1 mAB, or both anti-fibronectin receptor (FNr) antisera. Overall these results indicate that C. albic ans yeast and germ tube phases express a receptor antigenically relate d to alpha 5 beta 1 integrin which mediates their adhesion to FN. The alpha 5 beta 1 integrin-like receptor expression on C. albicans could be relevant for fungus-host interaction and in the dissemination proce ss of Candida infection.