ANTIBODY-RESPONSE THAT PROTECTS AGAINST DISSEMINATED CANDIDIASIS

We previously showed that surface mannans of Candida albicans function as adhesins during yeast cell attachment to mouse splenic marginal zo ne macrophages. The mannan adhesin fraction was encapsulated into lipo somes and used to vaccinate mice over a 5- to 6-week period. Circulati ng agglutinins specific for the fraction correlated with increased res istance to disseminated candidiasis. Antiserum from vaccinated animals protected naive BALB/cByJ mice against C, albicans serotype A and B s trains and Candida tropicalis. Antiserum also protected SCID mice agai nst disseminated disease. The serum protective ability was stable at 5 6 degrees C, but this ability was adsorbed by C, albicans cells. The a ntiserum was divided into three fractions after separation by high-per formance liquid chromatography. One fraction contained all of the aggl utinin activity and transferred resistance to naive mice, A second fra ction also transferred resistance. Two monoclonal antibodies (MAbs) sp ecific for candidal surface determinants were obtained, MAb B6.1 is sp ecific for a mannan epitope in the adhesin fraction, and MAb B6 is spe cific for a different epitope in the fraction, Both MAbs are immunoglo bulin M, and both strongly agglutinate candidal tells, but only MAb B6 .1 protected both normal and SCID mice against disseminated candidiasi s. In one experiment, 10 normal mice were given MAb B6.1 and challenge d with yeast cells. Six mice survived the 67-day observation period; 4 of the survivors were cured as evidenced by the lack of CFU in the ki dney and spleen. Our studies show that antibodies against certain cell surface antigens of C. albicans help the host resist disseminated can didiasis.