Visualization of immunoadsorption by immunofluorescence

Visualization of immunosorption by scanning electron microscopy

Immunosorption has become a very important biochemical and serological tool and it is the purpose of this paper to visualize this process qualitatively using the scanning electron microscope. Different carriers (i.e. CNBr activated cellulose and Sepharose, glutaraldehyde treated acrylamide-agarose beads Magnogel, and polystyrene cover slips) were coated with different antibodies and incubated with their homologous antigens such as pneumococci, ferritin, polymeric Salmonella flagellin and mechanically detached flagella, as well as tetanus toxoid, E. coli bacteriophage T4 and Rota virus particles. As negative controls the sorbents were incubated with heterologous antigens.

Studies of the distribution of proteins bound to CNBr-activated Sepharose 6B at the electron-microscopic level

Proteins were covalently attached to Sepharose by the CNBr method. Their distribution across the carrier beads was studied at the electron microscopic level. The approach has been to ferritinstain and to section the gel beads. Ferritin was either coupled directly to the polysaccharide backbone of the carrier or conjugated with pure rabbit anti-aminopeptidase in order to visualize covalently bound leucine aminopeptidase by the immunferritin technique. The results corroborate earlier fluorescence microscopic findings of a uniform protein distribution, provided that a number of conditions are fulfilled.

Microfluorometric evaluation of conjugate-specificity with the defined antigen substrate spheres (DASS) system

Six fluorescent antihuman Ig preparations were tested for their Ig class specificity by reacting them with highly purified IgG, IgM, IgA, and OVA coupled covalently to Sepharose beads. OVA was used as a measure for nonimmunologic binding. Bead fluorescence was determined by microfluorometry. The amounts of USS and NSS were expressed quantitatively. These data were compared with the performance of these particular conjugates in a biologic system, namely, monoclonal bone marrow cells. Five of the six conjugates satisfied the requirement of monospecific activity; one did not. At a dilution of 1 : 8, the five monospecific conjugates reacted between five and 50 times stronger with their appropriate antigens than with OVA-coupled beads. Cross reactivity with other Ig classes, after correction for OVA staining was maximally 6%. The conjugate that was nonspecific in the bone marrow system gave very high cross reactivity with the Ig-coupled beads. A good correlation was found between OVA bead staining and nonimmunologic binding of conjugates in bone marrow slides. In this respect, conjugates prepared from antibody preparations isolated by solid immunoadsorbents proved to be superior to globulin or whole IgG fractions. Ig coupled to Sepharose beads seems to represent a very promising substrate for conjugate specificity testing.