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J J Cebra

Publications and source records attributed to J J Cebra.

At least 109 records · Page 6Linked to original sources
PubMed1976

Structure of the heavy chain from strain 13 guinea pig immunoglobulin G1: isolation of cyanogen bromide fragments.

Guinea pig serum contains two isotypes of immunoglobulin G: IgG1 and IgG2. These immunoglobulins are antigentically distinct from each other and they mediate different biologic processes in the same guinea pig, although they share the ability to bind the same antigen. An attempt was made to study the primary structure of the gamma1 heavy chain from IgG1 in comparison with the largely known primary structure of the gamma-heavy chain from IgG2, with the aim of demarcating the structural differences between these molecules. IgG1 was isolated from the serum of immune strain 13 guinea pigs. Both IgG1 and the gamma1 chain were digested with CNBr. Nine fragments were isolated from both digests by gel filtration procedures before and after reductive cleavage of disulfide bonds. These fragments appear to account for the entire approximately 444 residues in the gamma1 chain. Amino acid composition data of CNBr fragments suggest that at least the amino terminal approximately 182 residues of the gamma1 and gamma2 chains are very similar. Two of the fragments which have been isolated have amino acid compositions suggesting their derivation from the "hinge" region and carboxyl terminus of the gamma1 chain.

Amino Acids↗
PubMed1975

Structural and thermodynamic basis of affinity in anti-dinitrophenyl antibody.

The thermodynamic quantities of the anti-dinitrophenyl antibody-hapten interaction are reported for rabbit, goat, and guinea pig antibodies. Rabbit and goat antibodies had similar exothermic enthalpy changes for their reaction with 2,4-dinitrophenyl-L-lysine (-13.9 and -14.8 kcal/mol, respectively). The enthalpy change with guinea pig antibody was much less exothermic (-8.7 kcal/mol), and this value was the same for two guinea pig antibody preparations that differed in affinity by almost two orders of magnitude. A heterogeneous goat anti-dinitrophenyl antibody preparation was fractionated on a molecular sieve column in the presence of a bivalent ligand, a procedure that has been reported to separate antibodies according to differences in the depth of interaction with the ligand. The relationship of these differences in apparent site depth to changes in interactions with the hapten tail was examined by comparing the affinities of various fractions for two haptens. The results show that the presumed deeper sites have stronger interactions with the hapten tail. These studies suggest that the heterogeneity of anti-dinitrophenyl antibodies with respect to affinity results from differences in entropy driven lysyl side-chain interactions which arise from a heterogeneity in antigen binding site depth.

Animals↗
PubMed1975

Anti-dinitrophenyl antibody production in strain 13 guinea pigs fed or sensitized with dinitrochlorobenzene.

Guinea pigs fed dinitrochlorobenzene (DNCB) in corn oil become unresponsive tosensitization by later percutaneous applications of DNCB in olive oil. Sera taken from animals after feeding DNCB or after feeding and intradermal stimulation with DNCB contained no antibody detectable with 2,4-dinitrophenyl (DNP)-labeled T4 bacteriophage; if any antibody was present, its concentration was below 2 mu g/ml. Guinea pigs fed DNCB and then immunized with DNP on a foreign carrier, keyhole limpet hemocyanin (KLH), produced as much antibody 16 to 18 days later as did animals which had only been sensitized by intradermal injection of DNCB in phosphate-buffered saline and then immunized with DNP-KLH. The amount of antibody produced to DNP-KLH WAS MEASURED AT INTERVALS. In the fed animals, the titer either remained approximately the same or increased with time. In contrast, the sera of sensitized guinea pigs contained a decreasing antibody titer when the first and last bleedings were compared. Isoelectric focusing was carried out with sera from DNP-KLH-immunized animals after the sera were first mixed with a radiolabeled hapten. The antibody-hapten profiles revealed that the DNCB-fed animalss contained predominatly IgG2 in their serum by the time of their initial bleedings, whereas sensitized animals still contained a considerable proportion of more acidic antibodies having marked charge heterogeneity. Equilibrium dialysis measurements onpurified antibody from fed animals indicated an average binding affinity for hapten equivalent to that of purified antibody from sensitized animals. Feeding of DNCB did not cause any obvious decrease in the number of lymphoid cells able to bind 125I-labeled guinea pig IgG. Lack of reduction of the average binding affinity coupled with the retention of antigen-binding lymphoid cells, permit the conclusion that feeding DNCB to guinea pigs under the conditions used did not induce an unresponsiveness or a deletion of those cells which have the potential to produce anti-DNP antibody. Thus, feeding of guinea pigs with DNCB in oil seems to induce a central tolerance at the T cell level with adversely affecting their B lymphocytes. The antibody response obtained by immunization with DNP conjugated to a foreign carrier is not only quantitatively equivalent to that obtained in control animals but qualitatively it appeared to be more mature with respect to charge at a relatively early time (16 to 18 days. Since the antibody levels in serum from fed animals increased or remained approximately constant with time instead of waning as occurred in the DNCB-sensitized animals, feeding or sensitization with DNCB may also have affected some cell or cell product important in the regulation of antibody production.

Administration, Oral↗
PubMed1975

Rabbit Peyer's patches, appendix, and popliteal lymph node B lymphocytes: a comparative analysis of their membrane immunoglobulin components and plasma cell precursor potential.

We have characterized and compared the differentiative potential of B lymphocytes obtained from rabbit appendix (APP), Peyer's patches (PP), and popliteal lymph nodes (PLN) by immunofluorescence analysis of membrane immunoglobulin (Ig) components, by radioiodination of membrane components followed by isolation and identification of cell surface Ig, and by cell transfer studies. As assessed by cell transfer lymphoid cells from PP and APP appear to be highly enriched sources of IgA plasma cell precursors. In addition, these populations of lymphocytes have a small but significant potential to give rise to IgM and IgG plasma cells. In contrast, as shown previously (1), lymphocytes from PLN have a comparatively small potential to generate IgA plasma cells. The ability of cells from PLN and PP to give rise to plasma cells is correlated with the presence of 35 to 38% of lymphocytes from both sources having membrane light chain determinants detectable by immunofluorescent staining. When the cells were stained directly for mu chain determinants, about 33% of PLN cells and 28% of PP cells were positive. These latter percentages were shown to reflect cells bearing both endogenously synthesized b4 light chain and mu heavy chain. By indirect immunofluorescence, alpha and gamma chain determinants were also detected on PP and PLN cells; however, these Ig did not appear to be products of the cells which bore them as they were not regenerated after removal of Pronase. It was further demonstrated that purified rabbit copro-sIgA and colostral sIgA are cytophilic for PP and PLN cells. The results are discussed with respect to the origin of IgA plasma cells and the postulated bursal role of mammalian gut-associated lymphoid tissue.

Alkylation↗
PubMed1974

Specificity of antibodies: primary structural basis of hapten binding.

The primiary structure of the 83 residues of the NH(2)-terminus of the V(II), region was determined for each of three different antibodies to hapten which were produced in inbred guinea pigs. Each antibody had a different and distinctive primary structure within each of the two "hypervariable" regions (Hv1 and Hv2) included in the analyzed part of the variable region of the heavy chain. The sequences of Hvl and Hv2 in the three antibodies were either unique or of restricted variability compared with those of "normnal" immunoglobulin G2. Further implication of Hv1 and Hv2 in contributing to ligand-binding specificity of antibodies came from the placement of residues modified by affinity labeling reagents in these hypervariable regions.

Amino Acid Sequence↗
PubMed1974

Restriction of gene expression in B lymphocytes and their progeny. III. Endogenous IgA and IgM on the membranes of different plasma cell precursors.

Fluorescent antibody staining with antibodies to the f and g locus allotype markers present on rabbit alpha-chains revealed that the alpha-chain is the heavy chain on the Peyer's patch lymphocytes which previously had been shown to be the precursors of IgA-producing plasma cells. In addition, lymphocytes which had been stripped of membrane Ig with pronase and then cultured overnight to allow the sole expression of endogenous membrane Ig were found to have either the micro-chain or the alpha-chain on their membranes, but not both. These results suggest that most lymphocytes are restricted to the synthesis of one class of heavy chains at a time and that the commitment to synthesizing that particular heavy chain is maintained during the differentiation of lymphocytes into plasma cells. The proportion of lymphocytes with membrane alpha-chains is higher in the Peyer's patch and appendix, two gut-associated lymphoid tissues (GALT), than in other lymphoid tissues. Since the GALT are enriched sources of precursors for IgA-producing plasma cells compared to nongut-associated tissues, the presence of cells bearing membrane alpha-chains correlates well with the relative abilities of these tissues to generate IgA plasma cells.

Animals↗
PubMed1974

Restriction of gene expression in B lymphocytes and their progeny. II. Commitment to immunoglobulin heavy chain isotype.

To determine whether or not B lymphocytes are committed to the synthesis of a single immunoglobulin heavy chain isotype during their differentiation into plasma cells, rabbit lymph node and Peyer's patch cells were separated into populations with and without membrane IgM, using a fluorescence-activated cell sorter (FACS). The potential of the micro-bearing (micro+) and non-micro-bearing (micro-) cells to give rise to plasma cells both in vivo after transfer into irradiated recipients and in vitro in the presence of pokeweed mitogen was assessed by immunofluorescence techniques, and the relative proportions of the cytoplasmic Ig-stained cells (CSC) synthesizing each class of heavy chains were determined. Most of the CSC arising in vitro from micro-bearing lymph node and Peyer's patch cells contained IgM; all IgM CSC appeared to be derived from micro+ cells. Peyer's patch lymphocytes, however, did not generate IgM CSC after cell transfer and thus may be functionally different from lymph node micro+ cells. It was found also that nearly all of the many IgA CSC generated by Peyer's patch lymphocytes either in culture or after transfer were derived from micro- cells. Further fractionation of these micro- cells with the FACS after they had been membrane stained with anti-b locus allotype reagents revealed that the precursors of IgA CSC belong to a minor population of cells which do have b locus light chain determinants on their membranes, although they do not have detectable micro-chains. These cells are not found in lymph nodes. Although the majority of Peyer's patch and lymph node cells were found to be precommitted to the synthesis of a single heavy chain isotype, a small proportion of cells may not be similarly restricted. Some of the CSC with membrane IgM were found to contain cytoplasmic IgA or IgG. In addition, micro+ populations did give rise to low numbers of IgA and IgG CSC. The implications of these results, obtained under experimental conditions, on the normal differentiation of B lymphocytes in situ are discussed.

Animals↗
PubMed1974

Restriction of gene expression in B lymphocytes and their progeny. I. Commitment to immunoglobulin allotype.

Lymphocytes from b(5)/b(9) rabbits were stained in suspension with fluorescent antiallotype antibody reagents to selectively label with fluorescent molecules those cells bearing membrane immunoglobulin (Ig) of the b5 or b9 allotype. After staining, the cells were separated by the fluorescence-activated cell sorter into populations markedly enriched in cells bearing b5 or b9 membrane Ig or totally depleted of cells with detectable membrane Ig. The potential of these separated cells to give rise to Ig-synthesizing plasma cells either in vivo after transfer into irradiated recipients or in vitro during culture in the presence of phytohemagglutinin or pokeweed mitogen was assessed by immunofluorescence. The relative proportion of b5 and b9 cytoplasmic Ig-stained cells (CSC) arising from the separated cells was determined to test directly whether B lymphocytes and their progeny are committed to the synthesis of Ig of one allotype. It was found that b5- and b9-bearing cells gave rise almost exclusively to b5- and b9-producing plasma cells, respectively, in both the in vivo and in vitro assay systems. Most of these CSC were probably not derived from previously existing CSC but arose as the result of the differentiation of lymphocytes with membrane Ig. When cell populations totally depleted of Ig-bearing lymphocytes were cultured, very few CSC were found, indicating that the majority of immediate precursors of CSC have membrane Ig. These results suggest that individual B cell clones are phenotypically restricted to the expression of immunoglobulin genes on one chromosome; the significance of this clonal allelic exclusion is discussed.

Animals↗