Immunoprotection against systemic candidiasis in mice

We have previously described an immunosuppressive B cell mitogenic(ISM) protein, p43, produced by Candida albicans, which playsan important role in the survival of the microorganism in thehost. The N-terminal amino acid sequence of p43 was found tobe different from all amino acid sequences registered in updatedprotein databanks. Immunization of BALB/c mice with p43 partiallyneutralized the biological effects of this protein, namely depletionof bone marrow pre-B and B cells, the increased numbers of totaland large B and CD4⁺ lymphocytes, and the nonspecific polyclonalresponse of splenic IgG2a-, IgG2b- and IgM-secreting plaqueforming cells.immunization of BALB/c mice with p43 fully protectedthe mice against the fungal infection. In contrast, immunizationwith C. albicans sonicates (Cs) was not protective. Our dataindicated that specific antibodies against p43 protected, whereasthose against Cs facilitated C. albicans infection. Thus, theratio between anti-p43 and anti-Cs antibody titres was muchlower in the non-protected mice (Cs-immunized and control non-immunized)than in p43-immunized mice. Moreover, passive administrationof specific anti-p43 antibodies significantly protected againstfungal infection, whereas passive administration of specificanti-Cs antibodies markedly increased the susceptibility toC. albicans Infection. These observations are discussed on thebasis of alternative approaches of immunointervention.