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Biomedical subjects

F Karush

Publications and source records attributed to F Karush.

At least 37 records · Page 2Linked to original sources
PubMed1981

Restriction in IgM expression. III. Affinity analysis of monoclonal anti-lactose antibodies.

A clonal analysis has been made of the murine BALB/C response to lactose-containing immunogens with respect to the affinity restriction in IgM expression. Monoclonal IgM and IgG antibodies were prepared from antilactosyl hybridomas generated from mice immunized with p-aminophenyl-beta-lactoside (PAPL) coupled to BGG or with a vaccine of Streptococcus faecalis (Strain N). Association constants for the binding of monovalent derivatives of PAPL were measured by quenching fluorescence. These derivatives carried a probe (2,4-dinitrophenyl or 1-dimethylaminonaphthalene-5-sulfonyl) that served to quench the protein fluorescence when the ligand was complexed with the protein. The central finding was that with both immunogens a restriction in the affinity of IgM was demonstrated since the highest values exhibited by IgG antibody exceeded by at least a factor of 50 the highest comparable values of the association constants for IgM antibody. It is suggested that the hypothesis of germ-line restriction, previously proposed as the basis for the affinity restriction of IgM, may also be applicable to the T cell receptor since its distinctive properties parallel those of IgM antibody.

Animals↗
PubMed1980

Proximity of antibody binding sites studied by fluorescence energy transfer.

Fluorescence energy transfer experiments by steady-state and nanosecond monophoton techniques were carried out with a covalently linked hybrid rabbit IgG antibody containing one antilactose site and one anti-Dns [5-(dimethylamino)-1-naphthalenesulfonyl] site. The hybrid antibody was prepared from antilactose and anti-Dns antibody by mild reduction, dissociation into half-molecules in acid, and random reassociation with re-formation, to the extent of 80%, of the single disulfide bond between the heavy chains. Fractionation with an antilactose-specific immunoadsorbent yielded a population in which each IgG molecule contained no more than one anti-Dns site per antibody. The acceptor molecules used for intramolecular energy transfer were derivatives of p-aminophenyl beta-lactoside (PAPL): (dimethyl-amino)benzeneazo-PAPL and N-fluorescyl-PAPL. The fluorescence lifetime (24 ns) and quantum yield (0.57) of the bound Dns group were unaffected by the presence of the acceptor in the adjacent site. Three models were used to calculate the minimum distance between the adjacent sites of the IgG antibody based on the overlap in the emission and absorption spectra of the donor-acceptor pairs and the segmental flexibility of the immunoglobulin molecule. The calculations yielded values in the range of 5.5-7.0 nm for the minimum distance of separation between the antibody sites in solution and demonstrated a substantial energy barrier to the closer approach of the sites.

Animals↗
PubMed1980

Surface component of primate thymus-derived lymphocytes related to a heavy chain variable region.

In a study designed to determine whether T cells of man and higher primates express a surface component related to the variable region of immunoglobulin heavy chain (VH), chickens were immunized with the purified VH fragment of a monoclonal Waldenström macroglobulin. The antibody preparation reacted with a mu chain determinant contained in the Fd fragment and with individual determinants characteristic of the orginal Waldenström protein. As estimated by immunofluorescence analysis, a subpopulation of normal human peripheral T cells (approximately 30%) bound the anti-VH antibody. B-Cell lymphoma lines grown in vitro, as well as some T-cell leukemia lines of the cotton-topped marmoset (Sagiunus oedipus), also bound the anti-VH antibody. The VH-bearing component of the T-cell line 70-N-2 was labeled biosynthetically by incorporation of [3H]leucine and was precipitated specifically by anti-VH antibody. This component was characterized by an apparent mass of 70,000 daltons as assessed by polyacrylamide gel electrophoresis under reducing conditions in buffers containing sodium dodecyl sulfate. These data provide direct support for the hypothesis that some T cells express and synthesize a component related to immunoglobulin heavy chains.

Animals↗
PubMed1975

Antibody affinity. VIII. Measurement of affinity of anti-lactose antibody by fluorescence quenching with a DNP-containing ligand.

The method of fluorescence quenching by bound ligand for the measurement of antibody affinity has been extended to anti-lactose antibodies. The basis for this extension is the use of a lactosyl ligand covalently linked to the 2,4-dinitrophenyl (DNP) group. This group serves as a sensor of the bound state by causing fluorescence quenching similar to that observed with anti-DNP antibody. The synthesis and characterization of this new ligand, N-(Nalpha-acetyl,Nepsilon-DNP-L-lysyl)-rho-aminophenyl-beta-lactoside, are described. The affinity of its interaction with three rabbit IgG and one equine IgM antilactose antibody preparations has been measured. The Qmax values range from 24 to 47% and the calculated association constants from 2.5 times 10-5 M-1 to 7.2 times 10-5 M-1. For one IgG preparation, measurement of the association constant by equilibrium dialysis with the tritiated ligand gave a value of 6.75 times 10-5 M-1 compared to the value of 7.2 times 10-5 M-1 obtained by fluorescence quenching. It is evident that with monoclonal anti-lactose antibody the accurate determination of Qmax, which is possible in this system, provides another structurally dependent clonal characterization of the variable region of the antibody. This optical probe along with others can be used for the identification of individual clones of antibody-producing cells through time and inheritance.

Aminoglycosides↗
PubMed1975

Equine anti-hapten antibody. IX. IgM anti-lactose antibodies.

The immune response to a bacterial vaccine of Streptococcus faecalis (strain N) was characterized in all of the seven horses studied by the sustained production of about 90% IgM anti-lactose antibody over a period of 44 weeks with maximum values of the total antibody ranging from 4 mg/ml of serum to 12 mg/ml of serum. With respect to the binding of a lactose-containing ligand the association constants of the antibodies purified from sera obtained between 5 and 44 weeks fell in the range of 1 times 10-5 M-1 to 2 times 10-5 M-1. Not only was there no significant indication of maturation of a-finity in this period but there was a selective limitation of affinity compared to that of 7S antibodies. It was inferred that the synthesis of IgM antibody involves the selective utilization of V-H and/or V-L genes.

Adsorption↗