In vitro inhibition of the classical and alternate pathways of activation of human complement by N acetyl aspartyl glutamic acid (NAAGA).

A synthetic dipeptide, magnesium salt of N-acetyl-L-aspartyl-glutamic acid (NAAGA) identical to a natural dipeptide found as traces in cerebral tissues of mammalian brains, was shown to inhibit, in vitro, the hemolytic activity of both classical and alternate pathways complement; the required concentration of NAAGA was 2 to 10 mM. Cross immuno electrophoretic analysis demonstrated an inhibition of C3 cleavage by both classical and alternate pathway C3 convertases with 24 mM NAAGA. As expected, if C3 convertases were really the target of inhibition, the release of highly inflammatory C3a, C5a fragments scored by R.

Immuno-enzymatic study of IgG subclasses specific for allergen in house dust immediate hypersensitivity.

Investigation of the serum-specific IgE by the RAST technique and of the four specific subclasses of IgG in house dust allergy by an immuno-enzymatic assay was made among healthy control subjects, non-treated atopic patients and hyposensitized patients. There was evidence that the titer of specific IgE remains high in the treated patients regardless of their improvement or non-improvement clinically. A good prognostic significance, however, correlates with a low specific IgG4 titer in the serum, but the pathogenic significance of IgG4 cannot be determined until these immunoglobulins can be studied on the membrances of circulating basophils of hyposensitized patients.

[Study of X antigen of Salmonella typhi responsible for the production of protective antibody towards chick embryo].

Laboratory animals are not sensitive to human S. typhi strain (O+ Vi+). But the chick embryo is very susceptible to infection by this strain.

[Do immunization of rabbits by N-acetylgalactosamine and a disaccharide linked to a protein produce anti-microbial antibodies (author's transl)].

Rabbits were immunized with N-acetylgalactosamine linked to bovalbumine. They produced antibodies which precipitated this same sugar linked to human gamma-globulins but did not agglutinate Salmonella johannesburg which carry a side chain of N-acetylgalactosamine. The same immunization enhanced the titre of "natural" antibodies agglutinating human A red cells (which carry a terminal N-acetylgalactosamine) but they did not evoke such antibodies in rabbits with no "natural" hemagglutinins.