Immunological neutralization of cobrotoxin by its homologous precipitin and non-precipitin antibodies.

Anti-cobrotoxin antibodies can be separated into precipitin and non-precipitin antibodies. The precipitin antibody possesses the same binding affinity to cobrotoxin as non-precipitin antibody, but the neutralizing capability of the latter is superior to that of the former in blocking cobrotoxin binding to nicotinic acetylcholine receptor (nAChR). After preincubation with antibodies, cobrotoxin completely lost its binding activity to nAChR. The dissociation of cobrotoxin-nAChR complex by the antibodies was low, and 60% of the complex formation appeared to be irreversible. These results indicate that the neutralization of cobrotoxin by the antibody may predominantly involve unbound, receptor-free cobrotoxin. The relationships of neutralization capacity and binding affinity as well as bond strength between cobrotoxin and its antibodies are incongruous. Different local conformational changes of a unique Trp in cobrotoxin on binding with the precipitin and non-precipitin antibodies seem to lead to different accessibility for fluorescence quenchers. Characterization of the binding domains by immunoprecipitation with the antibodies correlated with the quenching results. Thus, the binding topography of cobrotoxin may play an important role over the binding affinity and bond strength in neutralization by cobrotoxin antibody.

The isolation of an allergen from extracts of Dermatophagoides pteronyssinus using a murine IgA myeloma with a specificity for phosphorylcholine.

The presence of a high molecular weight glycoprotein component bearing the hapten phosphorylcholine (Pc) has been demonstrated in some but not all extracts of house dust mite using a phosphorylcholine specific IgA myeloma protein (S107). The Pc bearing component was isolated from house dust mite extracts by precipitation at equivalence using whole myeloma serum and the isolated fraction was found to be allergenic as judged by a direct RAST assay using a highly house dust mite allergic human serum pool. RAST inhibition studies using free hapten and direct RAST studies using pneumococcal polysaccharide C-substance indicated that the Pe moiety did not contribute significantly to the immunodominant portion of the isolated allergen. Further studies indicated that the S107 isolated material was immunochemically different from the tridacnin reactive material and the con A reactive material previously isolated fom extracts of house dust mite.

Physicochemical and immunochemical characterization of the high molecular weight allergens from dermatophagoides pteronysisinus with particular reference to the tridacnin, Con-A and S107 reactive components.

High molecular weight allergens which react with the S107 murine IgA myeloma and with the lectins Concanavalin A (Con-A) and tridacnin have been identified and characterized in extracts of the mite Dermatophagoides pteronyssinus. Mite extract from two different manufacturers were fractionated by Con-A affinity chromatography. The major antigen in both the Con-A bound and unbound fractions, which was antigenically indistinguishable, reacted with tridacnin and the S107 myeloma. This high molecular weight, multi-reactive antigen corresponded to allergen Dpt 4, suggesting that Dpt 4 exists as isoallergens, each differing in the degree of glycosylation or in the type of carbohydrate moiety comprising the glycan part of the allergen. Mite media extracts also reacted with Con-A, tridacnin and the S107 myeloma but were not allergenic per se.

Different Tridacnins in different Tridacnid clams: a comparative study.

1. Haemolymph samples from different Tridacnid clams were tested for haemagglutinin activity, using normal and enzyme-treated red cells from different sources. 2. Precipitin reactions with these haemolymph fluids were performed in agar gel, using several defined glycosubstances of different origin. 3. In several experiments it could be demonstrated that in all Tridacnid haemolymph samples anti-galactosyl ("anti-galactan") specific lectins do occur, however, they definitely differ from each other.

Prevention of staphylococcal bacteriophage activity by antigen A precipitins in human sera.

Antigen A precipitins in human sera prevented plaque formation and propagation of staphylococcal bacteriophages. Over 20% of total IgG was removed from human sera by absorption with staphylococci containing antigen A. The specific precipitating antibody in rabbit antisera formed lines of idenity with antigen A precipitins in lower dilutions of human sera but formed lines of nonidenity with antigen A precipitins in higher dilutions of the same sera, suggesting both specific and nonspecific antigen A precipitins in human sera. The specific and nonspecific antigen A precipitins in human sera may prevent the in vivo activity of staphylococcal bacteriophages which have been demonstrated previously in animals whose sera do not contain either specific or nonspecific antigen A precipitins.