Conrad H. Schneider

The reaction of benzylpenicillin with carbohydrates at neutral pH with a note on the immunogenicity of hapten polysaccharide conjugates.

Abstract The reaction of benzylpenicillin with mono- and disaccharides, glycerol and certain glycols in aqueous solution at pH 7·4 is demonstrated by penamaldate assay of the incubation solutions and a concomitant measurement of penamaldate stability. Raffinose and dextran of molecular weight 20,000 were penicilloylated under these conditions and subsequently isolated by gel filtration. The preparations were relatively unstable and lost their penicilloyl groups mainly by liberation of free penicilloate. Penicilloylated dextran, which is an example of a hapten-polysaccharide conjugate, induced hapten-specific delayed type hypersensitivity in random bred guinea pigs. On the other hand, no circulating antibodies specific for the penicilloyl determinant could be detected.

Specific Inhibition of Allergic Reactions to Penicillin in Man by a Monovalent Hapten

The principle of specific hapten inhibition is classically used to demonstrate antibody specificity in vitro . The purpose of the reported studies was to investigate whether this pri

Studies on the direct neutral penicilloylation of functional groups occurring on proteins

Abstract 1. (1)|The reaction of benzylpenicillin with various amines, amino acids and peptides in buffered aqueous solution at pH 7.4 was studied by means of the penamaldate assay and penamaldate stability test. 2. (2)|In addition to e-aminogroups, α-aminogroups and the iminogroups of proline, hydroxyl functions, e.g. the hydroxyl present in C-terminal serine, reacted with benzylpenicillin. The penicilloylation of N-terminal glycine and oligoglycine is up to ten times faster than penicilloylation of the e-amino function. The presence of a close second aminogroup on the reacting molecule considerably accelerates the formation of penicilloylamides. 3. (3)|The guanidogroup of arginine and the imidazole-function of histidine do not react. N α - Z- dl -histidine slightly catalyzes the hydrolysis of benzylpenicillin to benzylpenicilloic acid at pH 9 and 11. 4. (4)|It is concluded that the rate of penicilloylation depends on the functional group involved and also on the neighbouring structure. Sites of preferential penicilloylation on proteins are to be expected.

Monovalent elicitation of passive cutaneous anaphylaxis by N1-DNCP-N6-BPO-diaminohexane.

Abstract N1-DNCP-N6-BPO-diaminohexane, a conjugate carrying one DNCP- as well as one BPO-haptenic group was synthesized and studied as a monovalent elicitor of PCA in guinea pigs passively sensitized by anti-DNCP- or anti-BPO antisera from the rabbit. Anti-DNCP reactions could be elicited only by intravenous injection of the antigen into animals intradermally sensitized by anti-DNCP antiserum. No elicitation took place when sensitization was by the intravenous route and the antigen given intradermally. This novel observation of a difference in PCA elicatation behaviour is restricted to monovalent elicitation and does not occur with divalent DNCP-antigen such as diaminohexane symmetrically substituted with DNCP groups at both ends. This antigen elicited PCA when given by either route. In animals sensitized by anti-BPO antisera N1-DNCP-N6-BPO-diaminohexane was not an elicitor of PCA since no reactions were evoked after intradermal or intravenous injection. The results are discussed in relation to earlier findings with analogous haptens. It is thought that monovalent elicitation requires the benzyl residue of BPO in N1-DNCP-N6-BPO-diaminohexane. This residue allows discrete hydrophobic binding either with a cofactor in the circulation or directly with certain histamine releasing cells.

Evaluation of intrinsic and extrinsic penicilloyl-specific immunogenicity of penicillins. The use of penicillin hydrolysis catalyzed by 3,6-bis-(dimethylaminomethyl) catechol.

Abstract Sensitization to penicillins may be due to conjugation reactions of penicillin itself in vivo (‘intrinsic immunogenicity’) or to contaminants such as penicilloylated protein impurities, polycondensation products or penicillenic acid disulfide (‘extrinsic immunogenicity’). The intrinsic and extrinsic penicilloyl-specific immunogenicity of a benzylpenicillin and a phenoxymethylpenicillin preparation were evaluated by immunizing rabbits with the penicillins before and after selective hydrolysis with 3,6-bis-(dimethylaminomethyl) catechol. As a measure of immunogenicity the production of penicilloyl-specific hemagglutinating antibody was used. Both penicillins exhibited intrinsic immunogenicity. The extrinsic immunogenicity was very low in both preparations.

Solubility enhancing haptens: Preparation and some properties of conjugates with dinitrocarboxyphenyl (DNCP) groups

Abstract Conjugations of 2-chloro-3,5-dinitrobenzoic acid o -DNCP-Cl) and 4-chloro-3,5-dinitrobenzoic acid ( p -DNCP-Cl) to aminoacid, aminoacid polymer, peptide and protein carriers mostly in aqueous solution at pH 10·5 are described. Dinitrocarboxyphenylation of HSA with p -DNCP-Cl was almost as fast as dinitrophenylation with water-insoluble dinitrofluorobenzene. DNCP conjugates are generally more soluble in aqueous media than comparable DNP conjugates. DNCP and DNP haptens do not crossreact well according to studies of haptenic inhibition of the neutralization of haptensubstituted T 4 -bacteriophages in the presence of anti-hapten antisera.

Molecular parameters in melittin immunogenicity.

Based on immunogenicity studies, two T‐cell epitopes in melittin were found to be functional in guinea pigs, one being centrally located, the other one residing in the C‐terminal chain. In Balb/c mice only the central epitope was found to be active. A human T‐cell clone was found by T‐cell proliferation studies to employ strictly the C‐terminal chain. Truncation of melittin peptides at the N‐terminus did not markedly affect the capacity of guinea pigs to develop anti‐IgG responses towards peptidic epitopes and towards a C‐terminally attached haptenic group. Attachment of various substituents inside and outside the T‐cell epitopic areas had no marked effect on antibody responses. In contrast, the substituents positioned within a T‐cell epitope abolished T‐cell proliferation. This difference between whole animal data and cellular in vitro responses is presently not understood.

Carboxymethyl cellulose additives in penicillins and the elicitation of anaphylactic reactions

Penicilloylierte Carboxymethylzellulose bildet sich schon in der Kälte beim Stehen von Penicillinlösungen mit Carboxymethylzellulose. Die entstehenden Konjugate sind befähigt, penicilloylspezifische, kutane anaphylaktische Reaktionen auszulösen.

Induction of Immunological Tolerance to the Penicilloyl Antigenic Determinant

The suppressive effect of cleavable penicilloylated dextran (BPO-DEX), whose directly bound penicilloyl groups undergo hydrolytic cleavage within 3 days under physiological conditions, on murine IgE antibody formation against the benzylpenicilloyl (BPO) determinant was investigated in BALB/c and C3H mice. Intraperitoneal administration of BPO-DEX during either primary or secondary IgE responses to BPO ascaris produced a reversible suppression of BPO-specific IgE, while not affecting carrier-specific IgE antibody formation. Suppression of longer duration, at least 10 weeks, was achieved, however, by repeated administrations of BPO-DEX. BPO-DEX itself did not generate detectable BPO-specific IgE antibodies. These results suggest that BPO-DEX might be one of the promising tolerogens in the prevention of penicillin allergy.

Molecular and Stereochemical Properties Required of Antigens for the Elicitation of Allergic Reactions

Antigens are molecules possessing several different immunological functions. At the present time, a more precise definition of these various functions under the terms of immunogenicity, antigenicity, allergenicity, and tolerogenicity may appear useful (Table 1). Whereas natural macromolecular antigens are usually able to perform simultaneously all possible functions of an antigen, the chemical manipulations of antigenic determinants and of carrier molecules and the preparation of synthetic antigens has permitted us in recent years to analyze somewhat better the molecular characteristics required for the one or the other function of antigens. Beside its theoretical interest, such an analysis has also permitted to obtain more insight in the molecular mechanism of various types of allergic reactions. Furthermore, the practical implications of this work lie at hand: according to circumstances, it could be most desirable in human medicine to prepare and administer antigens possessing solely one or the other of the possible functions.