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J Clin Microbiol. 1979 July; 10(1): 19-26

1 Clinical Microbiology Laboratory, Clinical Pathology Service, Veterans Administration Medical Center, San Francisco, California 94121
a Department of Laboratory Medicine, University of California, San Francisco, California 94143
ABSTRACT
Normal fresh and heat-inactivated (56°C, 30 min) human sera (80 vol%, i.e., 80% [vol/vol] of a 2-ml assay volume) killed Bacillus subtilis ATCC 6633 cell inocula of 1.5 x 104 colony-forming units per ml within 1 to 2 h after exposure. The B. subtilis assay strain proved slightly and reversibly susceptible to 5 µg of egg white lysozyme per ml. Seitz filtration of fresh human serum completely removed ß-lysin activity; significant amounts of serum lysozyme were removed as well, as determined with the bioassay strain Micrococcus lysodeikticus ATCC 4698. However, bactericidal activity of human serum via classical or alternative complement pathway activation remained intact. Addition of 0.01 M dithiothreitol to fresh human serum abolished ß-lysin activity, but not that of serum lysozyme. Chelation of fresh and heat-inactivated human serum with 0.01 M MgCl2 + 0.01 M ethylene glycol tetraacetic acid, but not with 0.01 M ethylenediaminetetraacetic acid, markedly retarded ß-lysin activity; however, lysozyme activity remained unaffected. Chelation of serum with 0.01 M MgCl2 + 0.01 M ethylene glycol tetraacetic acid + 0.01 M CaCl2 completely abrogated ß-lysin activity, but not that of lysozyme. Absorption of human serum with 10 mg of bentonite per ml (10 min, 37°C) completely removed ß-lysin and lysozyme activity, but failed to affect serum bactericidal activity against Escherichia coli control strain C. Reconstitution of 50 vol% of bentonite-absorbed serum with 40 vol% of heat-inactivated human serum restored both ß-lysin and lysozyme activity. Addition of either 63 to 500 µg of sodium polyanetholsulfonate per ml or 63 to 500 µg of sodium amylosulfate per ml to 80 vol% of fresh human serum completely neutralized ß-lysin activity for the entire observation period of 22 h.
Present address: Institut für Hygiene und Mikrobiologie, Haus 43, 6650 Homburg/Saar, West Germany.
| Antimicrob. Agents Chemother. | Clin. Microbiol. Rev. |
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| Clin. Vaccine Immunol. | ALL ASM JOURNALS |
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