Biomedical subjects
Publications and source records attributed to J W UHR.
Nascent protein synthesis is associated with polyribosomes in extracts of lymph node cells removed from hyperimmunized rabbits, if the ribonuclease activity in such extracts is inhibited. Prior treatment of the cells with actinomycin D markedly decreases protein synthesis by polyribosomes.
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Intravenously administered 7S antibody is more effective than 19S antibody in inhibiting the formation of antibody to bacteriophage X174. Since considerable amounts of 7S antibody are needed for inhibition, serum antibody formation may act as a "feedback" mechanism to prevent hyperimmunization.
Specific immunologic tolerance to bovine serum albumin (BSA) was induced in approximately one-half of the rabbits that had been primarily immunized and were prepared for a secondary antibody response to BSA. The state of tolerance lasted for several months in the majority of rabbits and was not easily terminated by immunization with human serum albumin followed by BSA.
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The formation of antibodies to bacteriophage T(2) in vitro was inhibited by 5 X 10(-8)M actinomycin D. This result is consistent with the concept that antibody formation depends upon DNA-dependent RNA synthesis.
The fetal lamb in utero is able to form large amounts of specific antibody in response to antigenic stimulus as early as the 66th to 70th day of the 150 day gestation period. Among the several antigens employed, the fetal lamb responded earliest, and with the highest titers, to bacteriophage varphiX. Slightly less effective as an antigen was horse ferritin, while ovalbumin proved to be a weak antigen, especially in younger fetuses. Ineffective in stimulating an antibody response at any time during fetal or early neonatal life were diphtheria toxoid, Salmonella typhosa, and BCG. Thus, it may not be feasible to fix precisely the time of onset of immunologic responsiveness in a species, inasmuch as it appears to differ so greatly from one antigen to another. The quantity of antibody found 10 days after varphiX immunization was not significantly different in fetuses injected at 60 to 120 days of gestation. The earliest anti-phage antibody produced by the lamb fetus is a macroglobulin sensitive to the action of 2-mercaptoethanol. Only in older fetuses with longer lasting stimuli were appreciable amounts of 7S gamma-globulin antibodies formed. The conformity of these observations to theories on the ontogenesis of the immune response is discussed.
Injection of a sufficient dose of bacteriophage phiX 174 into guinea pigs results in the formation of rapidly sedimenting antibody molecules (19S), and later, slowly sedimenting molecules (7S). Above a threshold dose of antigen, the relative rate of 19S formation is maximal and dose-independent; below this dose, slower relative rates are obtained. The time for doubling the serum 19S level is as short as 6 to 8 hours, suggesting that the absolute rate of antibody formation per cell is increasing in addition to proliferation of antibody-producing cells. Synthesis of 19S after injection of 10(10) phiX virtually ceases at 10 days after which 19S antibody activity disappears from the circulation with a half-life of approximately 24 hours. A second injection of phiX on day 5 or 9 prolongs 19S synthesis, indicating that antigen not only can regulate the relative rate, but also is essential for continued synthesis of 19S. 19S synthesis is also prolonged in guinea pigs by injection of phiX with endotoxin or by 400 r whole body x-irradiation 24 hours after injection of phage into rabbits. The primary 7S response is not detected until approximately 1 week after immunization and relative rates are antigen-dependent. Primary 7S synthesis can continue for many months and leads to preparation for a secondary antibody response (immunological memory) during which only 7S is detected. In contrast, in animals that form precipitating 19S without detectable 7S, a second injection of phage 1 month later results in a second 19S response which closely resembles the first. These findings have led to the suggestion that formation of 19S does not lead to persisting immunological memory.
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Newborn guinea pigs (less than 24 hours old) are highly susceptible to the lethal effect of endotoxin and susceptibility decreases with age. The vulnerability to endotoxin has not been attributed to hypofunction of either the adrenal gland or the reticuloendothelial system of the newborn, since prior injection of corticosteroids provides only partial protection to endotoxin and newborn guinea pigs can efficiently remove colloidal substances from the circulation. In contrast to adults, newborns do not develop a delayed inflammatory reaction following intradermal injection of endotoxin, and after intravenous challenge frequently fail to display neutropenia and sustained fever.
Injection of a small bacteriophage phiX 174 into guinea pigs results in an accelerated elimination of phage detectable as early as 24 hours after injection. The immune nature of the accelerated elimination is indicated by its specificity, by the appearance of excess specific serum antibody after phage elimination, and by the prevention of accelerated elimination by 400 r whole body x-irradiation of guinea pigs prior to injection of phage. The early antibody response is considered to be a primary one since an analogous response occurs in newborn guinea pigs, antibody is not detectable in the sera of non-immunized animals, and the second challenge with phiX stimulates a serum antibody response 100-fold greater than that after primary immunization. The early detection of immune elimination appears to be due, in part, to the small amounts of phage employed, since larger doses of phage delay the time of onset of detectable immune elimination. The early rise of serum antibody in the primary and secondary response appears exponential with a similar rate constant of antibody formation. The rate constant is also independent of dose. These findings have led to the suggestion that during this exponential phase, the relative rate of antibody formation at a cellular level may be constant for a given antigen.
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