The effects of monoclonal antibodies against iC3b receptors in mice with experimentally induced disseminated candidiasis.

CR3 (iC3b receptor), composed of CD11b/CD18, is a beta 2 integrin. A protein that shares antigenic and structural homology with the alpha-chain of CD11b/CD18 has been isolated from the surface of Candida albicans. This molecule is thought to be essential in the pathogenesis of disseminated candidiasis. To evaluate the effects of anti-iC3b receptor antibodies on adhesion between human dermal microvascular endothelial cells (HDMEC) and C. albicans, and in treatment of candidal infection, a binding assay of C. albicans to cultured HDMEC was performed in vitro. An anti-iC3b receptor-specific monoclonal antibody was administered to mice infected with C. albicans. The mice were monitored for mortality and renal involvement by culture and histopathological findings. Flow cytometric analysis demonstrated surface expression of iC3b receptor on C. albicans. The adherence of C. albicans to HDMEC was significantly decreased by treatment with anti-iC3b receptor antibodies. Anti-iC3b receptor antibodies significantly increased the survival time and rate while lowering the renal fungal burden. The iC3b receptors are involved in the adherence of C. albicans to vascular endothelial cells and are likely to be involved in the pathogenesis of disseminated candidiasis. The increased survival in mice infected with C. albicans after treatment with anti-iC3b receptor antibodies indicates that this modality may be beneficial for future development of a new therapy for candidiasis.