[Plasmodia from lemurs used as antigens in the indirect immunofluorescence reaction. Crossed reaction with Plasmodium falciparum].
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In human sera the specific reactions and cross reactions of antibodies directed against the penicilloyl groups were determined using different penicilloyl derivatives as antigen. The penicilloyl group providing the highest titre in one Ig class was said to define the specific reaction for this Ig class. This criterium was justified by the fact that antibodies evoked by long-term treatment with benzylpenicillin showed specific reaction to the benzylpenicilloyl group. Moreover, specific reactions of antibodies of different Ig classes in one serum were the same. Both the side chain and the thiazolidine ring of the penicilloyl group can serve as antigenic determinants.
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Serotonin release from rat basophilic leukemia (RBL) cells, sensitized with a DNP-binding monoclonal IgE, was stimulated with solid surface (polystyrene)-bound DNP-amino acids. The stimulatory potency of DNP-amino acids was dependent on the structure of amino acid attached to DNP. Generally, DNP-amino acids with high affinities to the sensitizing IgE (I(50) less than 10 microM) were stimulatory in polystyrene-bound form; DNP-amino acids with lower affinities (Pro, Cys, Trp), and aliphatic aromatic DNP-amino acid derivatives were inactive. In addition to structural analogues of DNP, lymecycline, that is chemically unrelated to DNP but was found to have high affinity to IgE(aDNP), was also stimulatory in this system. This drug, and various quinones (e.g. acenaphthene-quinone) in BSA-conjugated forms also stimulated serotonin release from RBL cells sensitized with IgE(aDNP). These studies suggest that (1) There is a threshold of intrinsic ligand binding affinities at approximately I(50) = 10-100 microM; ligands with lower affinities do not stimulate mediator release even if they are presented in multivalent forms; (2) The above affinity threshold for mediator cell stimulation is valid for various ligands, irrespective of their chemical similarity to the immunogen; (3) Multispecific stimulation of mediator release may contribute to the frequently observed allergic cross-reactions, false positive tests for allergies, and anaphylactic reactions to drugs upon first exposure.
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Cross-reactions between Mycobacterium bovis BCG and various other mycobacteria, Nocardia asteroides, Corynebacterium pyogenes and Listeria monocytogenes were studied by incorporating antibodies against these bacteria in the intermediate gel of a crossed immunoelectrophoretic system with BCG antigen and anti-BCG antibodies. In the BCG reference system forty-four distinct antigenic components were recorded, of which thiryt-three cross-reacted with Mycobacterium tuberculosis, twenty-five with M. avium, twenty-one with M. suvalii, eighteen with M. smegmatis, Fifteen with M. nonchromogenicum, twelve with M. phlei, eight with N. anteroides and two with C. pyogenes, whereas no cross-reaction was detected with L. monocytogenes. The value of the method for characterization of mycobacterial antigens is discussed. A taxonomic system based on this method appears particularly valuable for studies of non-cultivativable mycobacteria such as M. leprae. A majority of twenty-one patients with lepromatous leprosy had anti-BCG antibodies of restricted specificity, affecting only four or five BCG antigens, although one patient had twelve anti-BCG specificities. Most of these antibodies reacted with those BCG antigens that cross-react extensively with other mycobacteria.
Strains of four streptococcal types, 33, 41, 43, 52, and a nontypable strain, Ross, cross-reacted in precipitin and bactericidal tests. The homologous reactions, which determined the type, afforded the major protection and developed promptly and regularly in the serum of rabbits during immunization. The associated cross-reactions, on the other hand, appeared in the serum of certain rabbits only, were often not as strong as the associated homologous reactions, and required for their presence a longer period of immunization than the homologous reactions. Agar gel analysis of the homologous precipitin reactions revealed, as would be expected, reactions of serological identity, while those cross-reactions which were strong enough to test in this way formed bands of precipitate which joined with spur formation on the side of the homologous reaction. These experiments and others referred to in the text suggest that cross-protection, as demonstrated in bactericidal tests, is sufficiently widespread to be a factor in streptococcal immunity, if a corresponding protection occurs in vivo. Thus, streptococcal infection with one of the cross-reacting strains might confer, in addition to strong homologous protection, a certain amount of cross-protection.
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We present the case of a patient with facial dermatitis caused by sensitization to cocamidopropyl betaine. The patient also had positive patch-test reactions to cocamidoamine, 3-(dimethylamino)propylamine, and oleamidopropyl dimethylamine. The presence of 3-(dimethylamino)propylamine as an impurity in all of these substances can be hypothesized to explain these simultaneous reactions.
Sera with cytotoxic and haemagglutinating activity towards HLA-A2/28 were also shown to react with red blood cells (RBC) expressing the HLA-B17 antigen determinant. Absorption procedures with white blood cells (WBC) indicated that this was due to an HLA-A2/B17 cross-reaction. Absorption experiments with some other sera which previously had shown cytotoxic and haemagglutinating activity towards different HLA specificities, revealed broad cross-reaction related to HLA-B locus antigens.
The MB40.3 monoclonal antibody binds to four distinct HLA-B molecules; B7, B40, B40*, and B27. With Fab' fragments only the interaction with B7 and B40 was detected and the affinity for both was the same (1-2 X 10(8) M-1) suggesting the epitope is shared by the two molecules. Unlike many antibodies for which low affinity is due to a high-dissociation constant, that of MB40.3 results from a very low-association rate constant, coupled with a low-dissociation constant. In consequence, the affinity and avidity of Fab', F(ab')2, and IgG for B7 and B40 were found to be of a similar magnitude, soluble B7 was a more efficient competitor for antibody than cell surface B7 and in practice antibody bivalency was of little importance. The forward rate constant could be increased by removing Fc from the antibody or by removing sialic acid from the cells by treatment with neuraminidase. The neuraminidase treatment also produced an increase in the number of detectable cell surface HLA-A,B molecules. The affinity of MB40.3 for B40* and B27 was estimated to be less than 4 X 10(6) as no binding with Fab' was detected due to a high-dissociation rate. For these two HLA-B molecules bivalent attachment was critical, and it increased the strength of interaction with cell surface B40* and B27 to a point where the avidities were comparable to those obtained with B7 and B40, with B40* interacting more strongly than B27. The epitopes recognized by MB40.3 on B40* and B27 were thus shown to be structurally different from each other and from those on B7 and B40. The properties of this antibody contrast with those of other anti-HLA-A,B we have studied (Ways, J.P., and Parham, P. (1983) Biochem. J. 216, 423-432).
This study examines the genetic relationships between the recently emerged H1N2 swine influenza virus and viruses of H1N1 and H3N2 subtypes, and the extent of protection against H1N2 challenge in pigs immune after infection or vaccination with the other subtypes. There was low amino acid homology (70.4-71.9%) in the haemagglutinin (HA) gene between H1N1 viruses used for primary infection or vaccination and the H1N2 challenge strain, with 94-99 amino acid changes between these viruses involving all five antigenic sites. The NA genes of H3N2 viruses used for primary infection or vaccination showed higher amino acid homology with H1N2 (88.3-92.6%), while nucleoprotein (95.5-96.3% nucleotide identity) and matrix (96.8-98.4%) genes were most conserved between the three subtypes. Pigs immune as a result of intranasal inoculation with either H1N1 or H3N2 showed partial clinical protection against H1N2 challenge, and nasal virus excretion was 2 days shorter than in naive pigs. Moreover, dually infected (H1N1 + H3N2)-immune pigs showed complete clinical protection and H1N2 virus replication in the lungs and nasal secretions was either undetectable or markedly reduced. In contrast, a double vaccination with a commercial H1N1 and H3N2-based vaccine did not protect against H1N2 challenge. Haemagglutination inhibition (HI) or virus neutralisation (VN) tests of swine sera revealed little if any antigenic cross-reactivity between subtypes. These data suggest that serum HI or VN antibodies are not essential in heterosubtypic protection, but that mucosal or cellular immunity are probably involved. It is still unknown whether this type of cross-subtype protection will also occur in infection-immune pigs in the field.
Antisera produced in guinea pigs inoculated with Rickettsia rickettsii or Rickettsia montana were cross-reactive but sufficiently specific to identify the primary infecting agent. Guinea pigs immunized with R. montana were protected from fatal infection with R. rickettsii, although a few (25%) developed mild fever of short duration.
Human, bovine, and mouse C1q, a subcomponent of the first complement component, were purified, and both globular (GF) and collagen-like fragments (CLF) were isolated from human and bovine C1q. Antisera were produced in rabbits with these C1q or fragments, and F(ab')2 of immunoglobulin G (IgG) was purified from the antisera in order to avoid the possible non-specific binding of C1q of these animals to the Fc portion of rabbit IgG. Immunodiffusion analyses and radioimmune inhibition tests with these F(ab')2 showed that the definitive antigenic cross-reactivity was among C1q molecules of these animals, and that the regions participating in interspecies cross-reactions were located in both GF and CLF of C1q. These results suggest that both the C-terminal non-collagenous globular and the N-terminal collagen-like domains of C1q molecules may have remained highly conserved during evolution.
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