Human Recombinant Antimannan Immunoglobulin G1 Antibody Confers Resistance to Hematogenously Disseminated Candidiasis in Mice

Abstract

Mannan is a major cell wall component found in Candida species. Natural antimannan antibody is present in sera from most normal adults, but its role in host resistance to hematogenously disseminated candidiasis is unknown. The purpose of this study was to develop recombinant human antimannan antibody and to study its protective function. A phage Fab display combinatorial library containing Fab genes from bone marrow lymphocytes was screened with Candida albicans yeast cells and chemically purified mannan. One antimannan Fab, termed M1, was converted to a full-length immunoglobulin G1 antibody, M1g1, and M1g1 was produced in CHO cells. The M1g1 epitope was found in C. albicans serotypes A and B, Candida tropicalis, Candida guilliermondii, Candida glabrata, and Candida parapsilosis. Its expression was active at both 23°C and 37°C and uniform over the cell surface. BALB/c mice passively immunized with M1g1 were more resistant than control mice to a lethal hematogenous infection by C. albicans, as evidenced by extension of survival in an M1g1 dose-dependent manner (P, 0.08 to <0.001) and by reduction in number of infection foci and their size in the kidney. In vitro studies found that M1g1 promoted phagocytosis and phagocytic killing of C. albicans yeast cells by mouse peritoneal macrophages and was required for activation of the mouse complement cascade. Thus, human antimannan antibody may have a protective role in host resistance to systemic candidiasis.

Hybridoma Passage In Vitro May Result in Reduced Ability of Antimannan Antibody To Protect against Disseminated Candidiasis

“…Finally, when considering antibody constructs for protection against candidiasis, both specificity and complement-fixing activities are of critical concern. Whether human antimannan antibodies play similar roles in patient defense against candidiasis remains to be proven, but it is of interest that, in a recent paper, a human recombinant antibody specific for mannan shows many similarities to protective antibodies that we have described and the recombinant antibody is protective in mice (51).…”

Posaconazole Prophylaxis in Experimental Systemic Zygomycosis

“…The brains and kidneys from the control and the treated animals were aseptically removed, fixed in 10% neutral buffered formalin solution, embedded in paraffin, and stained with Grocott-Gomori's methenamine-silver nitrate. For each stained section, the numbers and the sizes of the infection foci (clusters of hyphae) (15) were counted in 20 consecutive microscopic fields by at least two observers, who were unaware of the treatment group, using a Leitz Orthoplan light microscope equipped with a micrometric eyepiece (objective, NPL Fluotar 25/0.55; eyepiece, Periplan GW ϫ10/26). The total measured area of tissue was equal to 15.7 mm 2 for each stained section.…”

Future therapies targeted towards eliminatingCandidabiofilms and associated infections

“…Other attempted therapeutic vaccine approaches include the use of human recombinant antimannan immunoglobulin G3 (IgG3) monoclonal antibody derived from immune serum of mice vaccinated with Candida-mannan containing liposomes [189], and human recombinant antimannan antibody G1 (igG1) [190], both of which were effective against disseminated candidiasis in mice. Worth mentioning also are anti--glucan antibodies induced by -glucan-conjugate vaccine [191], and idiotypic antibodies [192] which were effective experimental approaches against vaginal candidiasis in mice.…”