SEROLOGIC RESPONSE TO CELL-WALL MANNOPROTEINS AND PROTEINS OF CANDIDA-ALBICANS

The cell wall of Candida albicans not only is the structure in which m any biological functions essential for the fungal cells reside but als o is a significant source of candidal antigens. The major cell wall co mponents that elicit a response from the host immune system are protei ns ang glycoproteins, the latter being predominantly mannoproteins. Bo th the carbohydrate and protein moieties are able to trigger immune re sponses. Although cell-mediated immunity is often considered to be the most important line of defense against candidiasis, cell wall protein and glycoprotein components also elicit a potent humoral response fro m the host that may include some protective antibodies. Proteins and g lycoproteins exposed at the most external layers of the wall structure are involved in several types of interactions of fungal cells with th e exocellular environment. Thus, coating of fungal cells with host ant ibodies has the potential to influence profoundly the host-parasite in teraction by affecting antibody-mediated functions such as opsonin-enh anced phagocytosis and blocking the binding activity of fungal adhesin s for host ligands. In this review, the various members of the protein and glycoprotein fraction of the C. albicans cell wall that elicit an antibody response in vivo are examined. Although a number of proteins have been shown to stimulate an antibody response, for some of these species the response is not universal. On the other hand, some of the studies demonstrate that certain cell wall antigens and anti-cell wall antibodies may be the basis for developing specific and sensitive ser ologic tests for the diagnosis of candidasis, particularly the dissemi nated form. In addition, recent studies have focused on the potential for antibodies to cell wall protein determinants to protect the host a gainst infection. Hence, a better understanding of the humoral respons e to cell wall antigens of C. albicans may provide the basis for the d evelopment of (i) effective procedures for the serodiagnosis of dissem inated candidiasis and (ii) novel prophylactic (vaccination) and thera peutic strategies for the management of this type of infection.