Functional Analysis of Ficolin-3 Mediated Complement Activation

The recognition molecules of the lectin complement pathway are mannose-binding lectin and Ficolin -1, -2 and -3. Recently deficiency of Ficolin-3 was found to be associated with life threatening infections. Thus, we aimed to develop a functional method based on the ELISA platform for evaluating Ficolin-3 mediated complement activation that could be applicable for research and clinical use. Bovine serum albumin (BSA) was acetylated (acBSA) and chosen as a solid phase ligand for Ficolins in microtiter wells. Binding of Ficolins on acBSA was evaluated, as was functional complement activation assessed by C4, C3 and terminal complement complex (TCC) deposition. Serum Ficolin-3 bound to acBSA in a calcium dependent manner, while only minimal binding of Ficolin-2 and no binding of Ficolin-1 were observed. No binding to normal BSA was seen for any of the Ficolins. Serum C4, C3 and TCC deposition on acBSA were dependent only on Ficolin-3 in appropriate serum dilutions. Deposition of down stream complement components correlated highly significantly with the serum concentration of Ficolin-3 but not with Ficolin-2 in healthy donors. To make the assay robust for clinical use a chemical compound was applied to the samples that inhibited interference from the classical pathway due to the presence of anti-BSA antibodies in some sera. We describe a novel functional method for measuring complement activation mediated by Ficolin-3 in human serum up to the formation of TCC. The assay provides the possibility to diagnose functional and genetic defects of Ficolin-3 and down stream components in the lectin complement pathway

Interaction of lectin pathway of complement-activating pattern recognition molecules with <i>M ycobacteria</i>

Summary We have demonstrated that mannose-binding lectin (MBL) recognizes various slow-growing, pathogenic mycobacteria [Mycobacterium tuberculosis (MTB), M. bovis, M. kansasii, M. gordonae] as well as non-pathogenic M. smegmatis. Recognition resulted in activation of the lectin pathway (LP) of complement and an enhancement of phagocytosis (shown for M. tuberculosis). Although MBL may be considered the main factor activating the LP upon recognition of mycobacteria, involvement of ficolins has also to be considered. Interaction of ficolin-3 with M. tuberculosis, M. bovis and M. kansasii, and ficolin-1 with M. tuberculosis and M. bovis was shown for the first time. Binding of recombinant MBL or ficolin-3 to MTB H37Rv led to the agglutination of bacteria and promoted their phagocytosis, but little effect was apparent with ficolin-1 or ficolin-2. Data from Western blots suggest mannosylated lipoarabinomannan (ManLAM) to be one of the main cell components of slow-growing mycobacteria, involved in LP activation. However, the LP was also activated by other cell fractions. Results presented here supplement considerably the data concerning the ability of complement-activating lectins to interact with mycobacteria. Ficolins (especially ficolin-3) might influence host response to infection and thus have clinical significance, at least as disease modifiers.</jats:p

Two new methods for estimating structural equation models: An illustration and a comparison with two established methods

The application of structural equation models (SEMs) is common in marketing and the behavioral sciences. Accordingly, the exploration of more effective methods to estimate SEMs is also a popular area of research. Croon (2002) and Skrondal and Laake (2001) have each proposed a new method for estimating SEMs, but since these proposals nearly a decade ago, these methods have been mostly overlooked by applied researchers. We suggest that reasons for this oversight may include not only a lack of guidance in implementing these new methods but also the absence of a formal comparison to review these new methods relative to the more familiar maximum likelihood structural equation modeling (MLSEM) and partial least squares (PLS). In this paper, our goal was to make the Croon and Skrondal-Laake (SL) methods more accessible to applied researchers. We first provide a step-by-step illustration of how to implement the Croon and SL methods. We also present the first comprehensive evaluation of the new methods relative to MLSEM and PLS. From this evaluation, we can better appreciate the circumstances under which these new methods are preferable to MLSEM and PLS. Thus, we intend to help readers understand how and when to apply these new methods

Role of the complement-lectin pathway in anapylactoid reaction induced with lipopolysaccharide in mice.: Eur.J.Immunol.

NRC publication: Ye