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R W Tofte

Publications and source records attributed to R W Tofte.

24 records · Page 2Linked to original sources
PubMed1980

Opsonization of four Bacteroides species: role of the classical complement pathway and immunoglobulin.

Previous investigators have suggested that opsonization of two Bacteroides species is mediated exclusively by the alternative complement pathway and requires immunoglobulins. In this study, the nature of the opsonic factors in nonimmune human serum for four species of Bacteroides was investigated by measuring uptake of [(3)H]thymidine-labeled bacteria by human polymorphonuclear leukocytes. Normal human serum, C2-deficient serum, immunoglobulin-deficient serum, and serum chelated with ethylene glycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid (EGTA), MgEGTA, and ethylenediaminetetraacetic acid (EDTA) were used as opsonic sources. Heat inactivation of each of these sera significantly reduced its opsonic activity for all four Bacteroides species, suggesting that serum complement was essential for effective opsonization. All strains were opsonized in the absence of the classical complement pathway; however, kinetics studies revealed that opsonization proceeded at a significantly faster rate when the classical complement pathway was intact. Although two strains were opsonized in immunoglobulin-deficient sera, opsonization was less efficient and appeared to occur via the alternative complement pathway. Unexpectedly, all strains were well opsonized by the classical complement pathway in 10% serum which had been effectively chelated with EGTA or EDTA. The explanation for this finding is unknown; however, it is possible that cell wall cations of Bacteroides species may participate in the activation of complement in chelated serum, resulting in effective opsonization. It was also found that Bacteroides, when incubated with an Escherichia coli strain in normal serum, could compete for opsonins and thereby reduce phagocytosis of E. coli. It is possible that competition for opsonins among bacterial species contributes to the synergistic role these organisms share in mixed floral infections.

Bacteroides↗
PubMed1979

Opsonic activity of normal human cerebrospinal fluid for selected bacterial species.

The opsonic activity of normal human cerebrospinal fluid (CSF) has not been well defined. In this study, the opsonic activity of normal CSF for laboratory and blood culture isolates of Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Hemophilus influenzae type b, and Neisseria meningitidis was measured by a quantitative assay employing radiolabeled bacteria and polymorphonuclear leukocytes. All isolates of S. aureus, except the Wood 46 strain, were opsonized in undiluted CSF (>50% uptake by polymorphonuclear leukocytes.) There was heat-stable and heat-labile opsonic activity in CSF for S. aureus. Only one blood culture isolate of E. coli was moderately well opsonized in undiluted CSF (26% uptake). None of the remaining laboratory or clinical isolates were opsonized in undiluted CSF. The S. aureus isolates were more readily opsonized in dilute normal serum than were the other bacterial species, and complement appeared to be the heat-labile opsonin in serum. However, complement may not be the heat-labile opsonin in normal CSF for S. aureus. In contrast to serum, complement C3 was not visualized on the staphylococcal cell surface by immunofluorescence microscopy and chelation of CSF did not diminish opsonic activity. This study demonstrates that normal CSF is opsonic for S. aureus but not for bacterial species that more commonly cause meningitis. These species differences in opsonic requirements may be important in the pathogenesis of meningitis.

Bacteria↗