The complement cascade is a unique sequence of molecular events occurring within the vascular system in which inactive plasma proteins synthesised by the liver are activated following tissue injury (Figure ) (McGavin and Zachary, 2007). The increase permeability of blood vessels during inflammation is stimulated, at least in part, by the complement system. The complement system is a complex system of 30 serum proteins. Many early components are serine proteases that are activated sequentially to form a cascade. The complement cascade is activated through any one, or more, of four pathways: the classical, the mannan-binding lectin (MBL), the alternative and the extrinsic protease pathways (Guo and Ward, 2005; Monk et al., 2007; Ricklin and Lambris, 2007). For further information, refer (Manthey et al., 2009). (Copied from article)
Amoebae from the genus Acanthamoeba are facultative pathogens of humans and other animals. In humans they most frequently infect the eye causing a sight threatening infection known as Acanthamoeba keratitis (AK), and also cause an often fatal encephalitis (GAE). A mannose-binding protein (MBP) has been identified as being important for Acanthamoeba infection especially in AK. This lectin has previously been characterized from Acanthamoeba castellanii as consisting of multiple 130 kDa subunits. MBP expression correlates with pathogenic potential and is expressed in a number of Acanthamoeba species. Here we report the purification of a similar lectin from Acanthamoeba culbertsoni and the production of a monoclonal antibody to it. The A. culbertsoni MBP was isolated by affinity chromatography using α-D-mannose agarose and has an apparent molecular weight of 83 kDa. The monoclonal antibody is an IgM that is useful in both western blots and immunofluorescence. We expect that this antibody will be useful in the study of the pathology of A. culbertsoni and in its identification in clinical samples.