Modified immune
serum globulin, prepared from human immune
serum globulin by a nonenzymatic method, is apparently safe for
intravenous administration to humans. The efficacy of the preparation was determined in experimental murine
infections with seven immunotypes of Pseudomonas aeruginosa. Intravenously administered 0.85 percent NaCl, 0.3 m
glycine, and 10 percent
human albumin did not protect against lethal
pseudomonas infection, whereas modified immune
serum globulin given by the same route did protect mice. In the mouse protection test, the mean dose of the preparation that saved 50 percent of mice infected with any of eight strains of P. aeruginosa was 480 mg/kg (range, 12-2,333 mg/kg). For five strains the 50 percent effective dose was smaller than 200 mg/kg. There was no correlation between the efficacy of modified immune
serum globulin in the mouse protection test and titers of antibody, as determined by bacterial agglutination.
Therapy of
pseudomonas infection in mice with modified immune
serum globulin was followed by a prompt and persistent decrease in the numbers of intraperitoneal bacteria. This finding is consistent with the interpretation that modified immune
serum globulin acts primarily as an
opsonin and not as an
antitoxin. Modified immune
serum globulin may prove to be useful in the treatment of human
infections.