C-reactive protein (CRP) has several properties that suggest that it may function as a bacterial opsonin. CRP shows binding reactivity with pneumococcal C-polysaccharide, the cell wall carbohydrate of Streptococcus pneumoniae. In this study we have demonstrated protection of mice against serotypes 3 and 4 of S. pneumoniae infection by a single prior injection of CRP. This effect was seen both in mice that lacked antibody to phosphocholine and in normal mice. Thus the opsonic properties of CRP previously described may be related to protection against pneumococcal infection.
In the studies described here we have attempted to evaluate the hypothesis that CRP may function in host defense using two systems in which CRP in the presence of C appears to have opsonic properties. In the first, CRP and C were found to stimulate ingestion of erythrocytes by human monocyte or mouse macrophages in vitro, and to alter clearance patterns in vivo. In the second, we have studied opsonization of S. pneumoniae by CRP and C. Experiments with human neutrophils indicate that although CRP and C can enhance opsonization of S. pneumoniae, this effect is more pronounced in the absence of antibody. In vivo CRP was found to protect mice against intravenous infection with S. pneumoniae.
A 52-year-old female patient with massive ascites due to lupus peritonitis is described. Skin biopsy specimens revealed typical features of systemic lupus erythematosus (SLE) in light microscopic and immunofluorescent examinations. Immune-complexes, antinuclear antibody and hypo-complementemiawere detected in the peritoneal fluid. The massive ascites responded dramatically to steroid pulse therapy. The levels of circulating immune-complexes, anti-nuclear antibody and complementin sera were also improvedafter such therapy. It was suggested that steroid pulse therapy may be useful for massive ascites due to lupus peritonitis.
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