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Category: Fungi and Fungal Pathogenesis
Innate Humoral Immunity to Fungi, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555815776/9781555813680_Chap31-1.gif /docserver/preview/fulltext/10.1128/9781555815776/9781555813680_Chap31-2.gifAbstract:
The humoral innate immune system has three key elements: the complement system; pattern recognition by the collectin protein, mannan-binding lectin (MBL); and naturally occurring antibodies that are reactive with carbohydrate antigens found in the fungal cell wall. This chapter considers each of the three systems of innate humoral immunity in turn, with an emphasis on recognition, amplification cascades, interaction between the systems, and the similarities and differences between fungi in their interactions with these systems. Normal human serum contains antibodies that are reactive with the C. albicans cell wall. Binding of these antibodies is followed by activation of the classical pathway with subsequent covalent binding of C3 fragments to the cell surface. Complement activation and the biological consequences of complement activation have been examined for most of the pathogenic fungi. It is likely that MBL is one of several redundant systems that provide host resistance to pathogenic fungi. There are several potential mechanisms by which pathogenic fungi might evade surveillance by innate humoral immunity. The candidal integrin-like protein probably has several properties that might contribute to virulence including molecular mimicry to avoid phagocytosis and adhesion to host tissues. The alternative pathway, MBL, and natural antibodies probably have redundant functions. As a consequence, it is possible that the host could lose one of these activities without loss of innate resistance.
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Biological consequences of activation of the complement system by pathogenic fungi