Nelson M. Vaz

Inhibition of specific immune responses by feeding protein antigens.

A profound and long-lasting state of specific immune unresponsiveness may be induced in adult inbred mice given a single dose of protein immunogens--such as ovalbumin or hemocyanin--by the digestive route. The degree of unresponsiveness induced by intragastric exposure to ovalbumin could not be achieved by intravenous injection of deaggregated ovalbumin solutions across a wide range of doses. Unresponsiveness induced by intragastric exposure to hapten-protein conjugates is specific to the carrier protein.

Immune responses of inbred mice to repeated low doses of antigen, relationship to histocompatibility (h-2) type.

Immunization of inbred strains of mice with repeated minute doses (0.1 to 1.0 microgram) of hapten-protein conjugates demonstrated wide differences in the magnitude of their antibody responses, which were related to the histocompatibility (H-2) type of the strains. Immunization with a single high dose (100 micrograms) of antigen failed to demonstrate these differences.

Inhibition of homocytotropic antibody responses in adult inbred mice by previous feeding of the specific antigen.

Profound and prolonged states of specific immunologic tolerance were induced in adult mice of high-responder genetic background by a single exposure to moderate doses of the specific antigen by digestive route.

Sensitivity to Intravenous Injections of Histamine and Serotonin in Inbred Mouse Strains

A large panel of inbred strains of mice and some of their Fl hybrids were tested on their sensitivity to the hemoconcentrating effects of intravenous injections of histamine alone, serotonin alone, or histamine-serotonin mixtures. Major differences in susceptibility were observed. Crosses and backcrosses were made between susceptible (SJL/J) and less susceptible (RF/J, C57BL/6J) strains; it was found that the sensitivity to vasoactive amines is, at least partially, inheritable.

Effects of Bordetella pertussis on the Sensitivity of Inbred Mice to Vasoactive Amines

Pretreatment with Bordetella pertussis was determined to increase significantly the hypovolemia induced by intravenous injections of histamine either alone or in mixture with serotonin in a total of 26 different strains of mice. Two factors affecting the mortality rates observed by challenge after B. pertussis treatment were: the sensitivity of the strains to vasoactive amines before B. pertussis treatment, and their resistance to acute hypovolemic shock. Appropriate crosses and backcrosses between resistant and susceptible strains failed to demonstrate a clear pattern of inheritance of the susceptibility to B. pertussis effects.

The nature of antigen--antibody complexes initiating PCA reactions in the guinea pig.

Summary Benzylpenicilloyl (BPO) haptens of widely different molecular size were compared for their efficiency in eliciting PCA reactions in guinea pigs sensitized with rabbit anti-BPO antibodies. Equimolar doses of different sized haptens were found to be equipotent in eliciting the PCA reactions. Therefore, in this system the elicitation of PCA reactions by multivalent haptens could also be compatible with a simple bridging hypothesis.

Passive Anaphylaxis in Mice with γG Antibodies. II. Release of Histamine with Heterologous γG Antibody Preparations

Summary Anaphylactic release of histamine was induced in mouse mast cells after sensitization with mouse, rat, or rabbit antibodies. As compared with homologous antibodies, rat antibodies were quite effective, whereas, rabbit antibodies were poorly effective. Guinea pig antibodies (γG1 and γG2) were ineffective. Pepsin-digested preparations of rabbit antibodies were unable to sensitize mouse mast cells, or mouse skin, for the PCA reaction.