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Biomedical subjects

K L Knight

Publications and source records attributed to K L Knight.

At least 163 records · Page 9Linked to original sources
PubMed1977

Additional rabbit IgA allotypes, f69, f70, g76,g77: control by the C alphaf and C alphag loci.

Genetic and immunochemical studies have led to the identification of four additional rabbit IgA allotypes controlled by the Calphaf and Calphag loci. The folowing linkage combinations of the VHa and the 'new' alleles were observed among the populations of rabbits studied: a1f70g76, a1f69g77, and a2f69g77. Cross-reactions among g74, g76, and g77 molecules with various anti-g anti-allotype antisera indicate that the IgA-g allotypic specificities are comprised of multiple antigenic determinants. These studies provide a basis for further understanding of the evolution and gnetic control of the immunoglobulin heavy chain chromosomal region.

Alleles↗
PubMed1976

Preferential expression of anti-azobenzenearsonate antibodies of heterozygous a1a3 rabbits in the a1 allotype.

The preferential expression of anti-As antibodies in the allotype a1 of heterozygous a1a3 rabbits immunized with As-TMA-BSA has been investigated by means of quantitative methods. The average content of the anti-As antibodies in a1 and a3 allotypes was 84 and 11%, respectively; the analogous values for anti-TMA antibodies were 41 and 56%, and for anti-BSA antibodies they were 54 and 41%. The molar anti-As/anti-TMA ratios in the heterozygous a1a1 rabbits sensitized with As-TMA-BSA. The very low yields of anti-As-antibodies of allotype a3 cannot be caused by a lack of genes for the production of anti-As antibodies of allotype a3 because a3a3 homozygotes produce considerable amounts of anti-As antibody of allotpye a3. Competition between lymphoid cells having anti-As receptors of different allotype and different affinity for the antigenic p-azobenzenearsonate determinant is discussed as a possible cause for the preferential expression in the a1 allotype.

Animals↗
PubMed1976

Heavy chain variable region allotypic sub-specificities of rabbit immunoglobulins. I. Identification of three subpopulations of a1 IgG molecules.

Four anti-al Ab subpopulations were isolated from an anti-al antiserum by sequential immunoadsorption chromatography. These four anti-al Ab subpopulations were differentially bound by two "limited heterogeneity" Abs having different components of the al allotypic specificity. Each of the four anti-al Ab subpopulations reacted with al IgG molecules obtained from a2 and a3 rabbits. A subpopulation designated anti-al Ab reacted with 100% of al IgG molecules. Thus, the anti-al-A Ab recognizes al determinants common to all al IgG molecules. Each of the other three subpopulations, designated anti-al-B Ab, anti-al-C Ab, and anti-al-D Ab, reacted with only a fraction of the al IgG molecules but the sum of the percentages of al IgG molecules which reacted with each of these three anti-al Ab subpopulations approximated 100% of the al IgG molecules. Thus each of the anti-al-B Ab, anti-al-C Ab, and anti-al-D Ab recognizes non-common determinants distinct for each of three subpopulations of al IgG molecules. Although 65 to 90% of IgG molecules in al homozygous rabbits have the al allotypic specificity, these IgG molecules are heterogeneous with respect to their antigenic determinants comprising the al allotype; at least three kinds of al IgG molecules are identified. This heterogeneity probably reflects variation in the amino acid sequence of the Vh region of al IgG molecules and, therefore, poses a similar argument which had led to the hypothesis of two genes for one polypeptide chain and to the theory of episomal insertions for the genetic control of immunoglobulin synthesis.

Animals↗
PubMed1976

Synchronous regulation of VH and CH allotypes among Ig molecules in multi-heterozygous rabbits suppressed with anti-VH allotype antibody: emergence of IgA from suppression prior to IgG and IgM.

Heterozygous rabbits of genotype a1n81f73g74/a2n82f71g75 were suppressed at birth for the VH region a1 allotype. At 8 weeks of age, quantitative analysis of serum IgG, IgM, and IgA molecules showed that the VHa1 specificity was effectively suppressed in the three classes of Ig and that the suppression was extended to the CH region n81 specificity on mu-chains as well as to the CH region f73 and g74 specificities on alphaf and alphag chains. At 26 weeks of age, analysis of serum IgG and IgM molecules showed that a1 was still suppressed to approximately the same extent in both Ig classes and the suppression was still extended to the CH region n81 specificity. However, at 26 weeks, the percentage of molecules with a1 specificity had doubled among serum and colostral IgA molecules and this increase was extended to the CH region f73 and g74 specificities. Thus, the suppressed allotypes reappeared first among IgA molecules. Our data are consistent with a regulatory mechanism which controls and synchronizes the expression of the VHa and the CH allotypes expressed on the same heavy chain. The order of the re-expression of the suppressed allotypes with respect to Ig class may allow further definition of selective regulatory mechanisms for the synthesis of Ig classes.

Animals↗
PubMed1975

Distribution of covalently bound and non-covalently bound secretory component on sbuclasses of rabbit secretory IgA.

The distribution of non-covalently bound secretory component (SC) on the two subclasses, IgA-f and IgA-g of rabbit secretory IgA (sIgA) was determined; the two subclasses were separated from each other by the use of antibody-immunosorbent columns and were subjected to SDS polyacrylamide gel electrophoresis. No SC appeared to be dissociated from the IgA-f molecules from each of 11 different rabbits; the IgA-g molecules, however, did have SC which was dissociated by SDS. Thus, all of the noncovalently bound SC on rabbit sIgA resides on the IgA-g subclass molecules.

Animals↗
PubMed1975

Differential susceptibility of rabbit sIgA subclasses to trypsin cleavage: characterization of the fragments obtained from the g subclass.

Rabbit secretory IgA (sIgA) was digested with trypsin at 37 degrees C for 30 min and four fractions were isolated by gel filtration. These fragments were characterized by ultracentrifugation, and by their antigenic properties as undigested sIgA, Fab and Fe (Two Fc fragments differing in their content of secretory component were obtained.) The IgA-f subclass molecules were resistant to cleavage and were found in the undigested sIgA fraction; the IgA-g subclass molecules were cleaved into Fe and Fab fragments. The g allotypic determinants of IgA-g molecules were found on both the Fc fragments and the Fab fragments. The Fc and Fab fragments obtained from trypsin-digested sIgA were compared by means of antigenic properties and peptide maps with the Fc and Fab fragments obtained from papain-digested sIgA; no differences attributable to the alpha-chain were found. Thus, papain and trypsin cleave the alpha-chain of IgA-g molecules at similar but not necessary identical positions.

Adsorption↗
PubMed1975

Cellular distribution of rabbit IgA allotypes.

Intestinal tissue from rabbits heterozygous at one or both of the alpha-chain subclass loci, i.e., f or g, was examined with mixtures of rhodamine-labeled and fluorescein-labeled antibodies each directed against one of the allelic products of the f or g locus. Individual plasma cells were stained by only one fluorescent reagent and thus exhibited both allelic exclusion and sublcass exclusion. In contrast, the epithelial cells of the Lieberkükhn's glands sid not exhibit allelic exclusion. Studies with rabbits heterozygous at the f and g loci revealed that the ratio of the number of cells expressing maternal-type f cells to paternal-type f is equal to the ratio of the number of maternal-type g cells to paternal-type g cells. These data are used to suggest that the expression of each of the genes in the heavy chain chromosomal region of a particular allogroup is under the same control.

Absorption↗
PubMed1974

Recombinant rabbit secretory immunoglobulin molecules: alpha chains with maternal (paternal) variable-region allotypes and paternal (maternal) constant-region allotypes.

A population of IgA molecules having heavy chains coded by two parental chromosomes in trans position has been identified in rabbits heterozygous at both the V(H)a locus, which controls allotypic specificities on the variable part of heavy chains, and the C(alpha)g locus, which controls allotypic specificities on the constant part of alpha chains. These recombinant molecules have alpha-chain allotypic specificities controlled by both the maternal V(H)a gene and the paternal C(alpha)g gene or conversely, the paternal V(H)a gene and the maternal C(alpha)g gene. These recombinant molecules were found in F(ab)(2alpha) fractions obtained after passage of F(ab)(2alpha) preparations through immunosorbent columns designed to remove one population of F(ab)(2alpha) molecules, i.e., g74- or g75-type molecules. The effluent F(ab)(2alpha) fractions were then examined by radioprecipitation methods for allotypic specificities controlled by the V(H)a and C(alpha)g loci. About 40% of the g75 F(ab)(2alpha) molecules from each of three rabbits with the a(1)g(74) and a(2)g(75) allogroups were alg75 recombinants. These alg75 recombinant molecules represented from 2.5-5.6% of the total unfractionated F(ab)(2alpha) sample. The F(ab)(2alpha) fractions from two rabbits with the a(1)g(75) and a(3)g(74) allogroups had from 1.8-8.2% recombinant molecules: some were alg74 recombinants and some were a3g75 recombinants. Somatic recombination as a mechanism responsible for the synthesis of polypeptide chains in which part of the information is obtained from one chromosome and part from the homologous chromosome is discussed.

Alleles↗