Anti-infective properties of vitamin A.

1. Six months after feeding a vitamin A free diet the liver content of mice was markedly reduced but not yet completely exhausted. These vitamin A deprived mice were either immunized with sheep erythrocytes or infected with Listeria monocytogenes.

[Influence of maternal antibodies on the primary and secondary immunoresponse of the juvenile organism (author's transl)].

The immunization of mice with sheep erythrocytes served as model for the materno-fetal transfer of specific antibodies. It could be shown that passively transferred antibodies are able to induce a long-lasting suppression of the primary and secondary immuno-response in the offspring. This holds true both for active immunization before pregnancy and for passive immunization shortly before term.

Immunoadjuvant effects of the synthetic muramyl-dipeptide (MDP) N-acetylmuramyl-L-alanyl-D-isoglutamine.

The adjuvant activity of the synthetic muramyl-dipeptide (MDP) N-acetyl-muramyl-L-alanyl-D-isoglutamine upon immunization of mice with BSA or SRBC was studied. MDP was found to significantly increase BSA-antibody formation and to favour the induction of anaphylactic reactions to BSA. In contrast, under the conditions employed, MDP only weakly stimulated the immune response to SRBC.

[Concentration of specific antibodies in commercially avaialable immunoglobulins (author's transl)].

Not significant differences in the composition or concentration of specific antibodies against microbial antigens could be measured in five commercially available human immunoglobulin preparations for intravenous use. Prediction of prophylactic or therapeutic efficiency of such preparations according to their antibody content seems to be only partially possible. Human immunoglobulins for intravenous use should be free from irregular antibodies against erythrocyte antigens of the Rh-systems, as found in one of the specimens tested.

[Influence of killed Bordetella pertussis cells on the resistance against infection with Listeria monocytogenes (author's transl)].

The influence of killed Bordetella pertussis cells (B.p.) on the cell-mediated resistance of mice against infection with virulent germs of Listeria monocytogenes has been studied.

Reversion of dextran sulfate-induced loss of antibacterial resistance by Bordetella pertussis.

Parenteral injection of dextran sulfate 500 (DS 500; 50 mg/kg of body weight) into mice caused a complete loss of resistance to a sublethal (2 X 10(3) to 5 X 10(3)) infection with Listeria monocytogenes. Such loss could be prevented by pretreatment of animals with 3 X 10(9) heat-killed Bordetella pertussis organisms (PO) 5 to 30 days before the administration of DS 500. The increased phagocytic capcity induced by PO was only exhausted when a fourfold dose of DS 500, effecting complete loss of antibacterial resistance (50 mg/kg ob body weight), was administered.

Suppression of the secondary immune response by specific antibody, when given together with the secondary antigenic stimulus.

It is generally believed that antibody-mediated immunosuppression can be only produced in non-primed individuals, and that this applies both to experimental animals and Rh-negative women at risk. However, in this paper it is reported that the additional injection of 0.2 ml of an antiserum to sheep erythrocytes (SE) together with a secondary antigenic stimulus of 10(8) SE into mice, primarily immunized by a tiny dose of 5 x 10(5) SE 28 days before, was capable of producing effective suppression of the secondary immune response.

[Influence of latent vitamin A deficiency of the mouse on the production of humoral antibodies against sheep erythrocytes and on the resistance against infection with Listeria monocytogenes (author's transl)].

Mice fed with a vitamin A free diet for several months did not develop signs of vitamin A deficiency. However, chemical analysis revealed a reduced content of vitamin A in the liver of such mice. The ability of these animals were latent vitamin A deficiency to produce antibodies against parenterally applicated sheep erythrocytes was not hampered.