Transgenic mice and transhybridomas producing chimeric mouse/human anti-human interleukin-2 receptor recombinant antibodies.

Transgenic mice were developed that secreted chimeric mouse/human anti-human interleukin-2 receptor (IL-2R) antibodies (Ab) into their serum. In addition, hybridomas producing the chimeric Ab in tissue culture were generated from the transgenic mice. The presence of the mouse/human immunoglobulin (Ig) transgene did not appear to affect rearrangement of endogenous murine Ig in the hybridomas. Serum levels of the chimeric Ab correlated with transgene copy number. Although many of the transgenic lineages had serum titers of the chimeric Ab comparable to endogenous mouse IgG, there was no apparent correlation with endogenous mouse IgG levels.

The role of complement in the opsonization of mucoid and non-mucoid strains of Pseudomonas aeruginosa.

Requirements for complement and/or antibody for opsonization were assessed for 34 strains of Pseudomonas aeruginosa. Included were mucoid strains from patients with cystic fibrosis (CF), non-mucoid derivatives of these strains, and non-CF strains with classical morphology. Non-CF strains are known to vary as to opsonic requirements, but this study shows that mucoid strains are also diverse. Among the 14 mucoid strains, five could not be opsonized and completely resisted phagocytosis. All non-mucoid strains can be opsonized. When the bacteria were incubated in fresh human serum and stained with fluorescein, conjugated anti-C3 non-opsonizable strains did not bind C3 on the surface whereas five of six mucoid strains, which could be opsonized by complement alone, stained with anti-C3. In mucoid strains, surface characteristics correlate with differences in functional requirements for opsonization. In non-CF strains this specificity was not seen. Most mucoid strains required an intact classical complement pathway for opsonization. A number of mucoid strains could not be opsonized in the absence of a functional alternative complement pathway whereas in contrast, non-CF strains were not greatly affected by inactivation of the alternative pathway.

Effect of iron saturation on the bacteriostasis of human serum: in vivo does not correlate with in vitro saturation.

Human serum inhibits the growth of a variety of human pathogens. One of the serum bacteriostatic components is transferrin, the major iron-binding protein. In the presence of transferrin, free iron, which is required for bacterial nucleoprotein synthesis, is unavailable and bacterial growth is inhibited. In an in vitro system, we tested the hypothesis that serum with highly saturated transferrin allows free iron to be available for rapid bacterial growth. We first confirmed the finding that addition of ionic iron sufficient to saturate transferrin in normal sera inhibits the bacteriostatic activity for Escherichia coli. In contrast, no differences were found in the growth rate of E. coli in sera from individuals representing the entire range of transferrin saturation found in humans (iron-deficient, normal, and thalassemic). This finding supports the thesis that iron added in vitro is more easily extracted than in vivo, where it is tightly bound to transferrin, and does not support the contention that ordinary iron treatment predisposes infants to infection.

Effects of route and time of administration of antiserum on protection of mice from lethal infection due to group B Streptococcus type III.

The present study examines a mouse model of infection due to group B Streptococcus serotype III (GBS-III) as to the route and timing of antiserum administration for protection and quantitation of bacteremia with and without antiserum. Data for these parameters are contrasted with those after challenge with serotype Ia of group B Streptococcus (GBS-Ia). An intraperitoneal injection of GBS organisms and protective antiserum from a single syringe can be used to create an animal model of disease. Intraperitoneal injection of GBS-III resulted in bacteremia at 0.5 h both in animals who did not receive antiserum (17.4 X 10(2) +/- 7.6 X 10(2) colony-forming units per ml of blood samples) and in animals who received antiserum (19.3 X 10(1) +/- 6.8 X 10(1) colony-forming units per ml). Although intraperitoneal injection of GBS-Ia also resulted in bacteremia evident by 0.5 h in unprotected animals (30.1 X 10(2) +/- 3.8 X 10(2) colony-forming units per ml), no bacteremia occurred in protected recipients of this organism. Bacteremia due to GBS-Ia and GBS-III logarithmically increased until at least 7 h. Bacteremia due to GBS-III in protected animals was cleared by 24 h. Protection against GBS disease did not require simultaneous or proximate administration of the organism and the antiserum. Mice could be protected from death after intraperitoneal challenge with GBS-III or GBS-Ia by antiserum administered intravenously or intraperitoneally from 6 h before to 2.5 h after challenge.