The complement system

Significant protection of mice by several polysaccharides other than glucan isolated from S. cerevisiae has been described (209). A 2.16-fold protection in the LD q q is observed for one modifier, MNZ, when given 15 min prior to irradiation. Glucan protects 2.25-fold in this same protocol. Many of these polysaccharides may act through activation of the complement system, rather than directiy on ceHs. 

A few examples of pure arabinans with effect in the complement system have been isolated from, for example, the fruits of Ziziphus jujuba (a-2,5-arabinofuranan) and from the roots of Bupleurum falcatum (Q -3,5-arabino-furanan-Q -l,4-glucan complex) [12,13]. 

Already in 1988 and 1991, Gao et al. [65,66] detected four different polysaccharides present in the leaves of Panax ginseng that had an effect on the complement system, but only two of them, the neutral, GL-NIa, and one of the acidic ones, GL-AIa, had potent activities at low concentrations. GL-NIa was found to be mainly an arabinigalactan type II polymer. GL-AIa was a polysaccharide with a rhamnogalacturonan core with neutral side chains of the AG-II type, confirmed by a strong reaction with the Yariv reagent and the methylation results. It was shown that the crude polysaccharide fraction contained KDO and DHA, suggesting the presence of Rhamnogalacturonan II in... 

Black pepper contains several polysaccharides of which one shows a strong effect as an immune enhancer based on the fact that the polymer is an anti-complementary polysaccharide. The polysaccharide has an Mw of approx. 40 kD. It is composed basically of rhamnose, arabinose, galactose and galac-turonic acid, and shows a high binding capacity for the Yariv reagent. This indicates that the side chain of the polymer is of the arabinogalactan type II, which is a common structure for several polysaccharides with an effect on the complement system [70]. 

The structure that appears to be important for the effect on the complement system is most probably the complex galactan ohgomer being composed of separate 1,3- and 1,6-hnked galactose chains with branch points being of 1,3,6 nature. These units have been proposed as the active sites for... 

The mechanisms of the allergy-like reactions to RCM are still a matter of speculation (table 2). Anaphylaxis to RCM has been discussed to be due to a direct membrane effect possibly related to the osmolality of the RCM solution or the chemical structure of the RCM molecule (pseudo-allergy) [2], an activation of the complement system [27], a direct bradykinin formation [28], or an IgE-mediated mechanism [3]. 

Collagen, the major component of most connective tissues, constimtes approximately 25% of the protein of mammals. It provides an extracellular framework for all metazoan animals and exists in virmally every animal tissue. At least 19 distinct types of collagen made up of 30 distinct polypeptide chains (each encoded by a separate gene) have been identified in human tissues. Although several of these are present only in small proportions, they may play important roles in determining the physical properties of specific tissues. In addition, a number of proteins (eg, the Clq component of the complement system, pulmonary surfactant proteins SP-A and SP-D) that are not classified as collagens have... 

Table 50-2 summarizes the functions of many of the plasma proteins. The remainder of the material in this chapter presents basic information regarding selected plasma proteins albumin, haptoglobin, transferrin, ceruloplasmin, aj-antitrypsin, aj i roglobulin, the immunoglobulins, and the complement system. The lipoproteins are discussed in Chapter 25. 

The Complement System Comprises About 20 Plasma Proteins Is Involved in Cell Lysis, Inflammation, Other Processes... 

The complement system resembles blood coagulation (Chapter 51) in that it involves both conversion of... 

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