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Biomedical subjects

C Bona

Publications and source records attributed to C Bona.

At least 73 records · Page 4Linked to original sources
PubMed1992

Influenza A virus transfectants with chimeric hemagglutinins containing epitopes from different subtypes.

Influenza virus transfectants with chimeric hemagglutinins were constructed by using a ribonucleoprotein transfection method. Transfectants W(H1)-H2 and W(H1)-H3 contained A/WSN/33(H1N1) (WSN) hemagglutinins in which the six-amino-acid loop (contained in antigenic site B) was replaced by the corresponding structures of influenza viruses A/Japan/57(H2N2) and A/Hong Kong/8/68(H3N2) (HK), respectively. Serological analysis indicated that the W(H1)-H3 transfectant virus reacted with antibodies against both the WSN and HK viruses in hemagglutination inhibition and plaque neutralization assays. Furthermore, mice immunized with W(H1)-H3 transfectant virus produced antibodies to the WSN and HK viruses. The results demonstrate that influenza virus transfectants can be engineered to express epitopes of different subtypes on their hemagglutinins.

Amino Acid Sequence↗
PubMed1991

Induction of antibodies to the envelope protein of the human immunodeficiency virus by immunization with monoclonal anti-idiotypes.

Anti-idiotypes that possess the internal image of antigen can induce protective humoral immunity toward microbes. Herein we demonstrate antigen mimicry by monoclonal anti-idiotypes of a distinct epitope of the human immunodeficiency virus (HIV) envelope protein that is defined by a synthetic peptide. This peptide, corresponding to amino acid residues 503-535 (peptide 503-535) of HIV-1 IIIB gp160, induced antibodies in three mammalian species that interacted with HIV-1 gp120 and inhibited in vitro syncytium formation caused by HIV-1, IIIB and MN isolates. Three monoclonal anti-idiotypes were generated against rabbit anti-gp120 antibodies specific for peptide 503-535. These anti-idiotypes recognize an interspecies cross-reactive idiotype expressed on mouse, chimpanzee, baboon, rabbit, and human anti-gp120 antibodies specific for peptide 503-535. The interaction with the cross-reactive idiotype is inhibited by synthetic peptide and HIV-1 gp160. Furthermore, rabbits immunized with the monoclonal anti-idiotypes produced antibodies that also bind HIV-1 gp120 and gp160 and recognized the epitope defined by peptide 503-535.

Amino Acid Sequence↗
PubMed1991

IgM anti-Fc gamma R autoantibodies trigger neutrophil degranulation.

Anti-Fc gamma R IgM monoclonal antibodies (mAbs) isolated from lipopolysaccharide-stimulated spleen cells from tightskin (TSK) mice were found to be polyspecific, reacting with a wide variety of molecules, including double-stranded DNA, topoisomerase, RNA polymerase, and different collagen types. Approximately 60% of the polyspecific IgM mAbs have anti-Fc gamma R specificity. These anti-Fc gamma R mAbs induce the release of hydrolases from both azurophil and specific granules of human neutrophils. 25-45% of the total cellular content (determined in Nonidet P-40 lysates) of neutrophil elastase, 10-25% of beta-glucuronidase, and 30-50% of alkaline phosphatase was released after incubation with the mAbs. The degranulation process was accompanied by dramatic morphological changes shown by scanning and transmission electron microscopy. The release of hydrolytic enzymes stimulated by the IgM anti-Fc gamma R mAbs was inhibited by preincubation of neutrophils with Fab fragments of either anti-human Fc gamma RII (IV.3) or anti-human Fc gamma RIII (3G8) mAbs. The binding of the anti-Fc gamma R TSK mAbs to human neutrophils was inhibited by Fab fragments of mAb 3G8. However, we found that the TSK anti-Fc gamma R mAbs do not bind to human Fc gamma RII expressed in either CHO cells or the P388D1 mouse macrophage cell line. Since the enzyme release could be inhibited by Fab fragments of mAb IV.3, we suggest that the signal transduction may require Fc gamma RII activation subsequent to crosslinking of the glycan phosphatidyl inositol-anchored Fc gamma RIII-1. These data demonstrate for the first time that polyspecific autoantibodies with Fc gamma R specificity can trigger neutrophil enzyme release via human Fc gamma RIII-1 in vitro and indicate a possible role for such autoantibodies in autoimmune inflammatory processes.

Animals↗
PubMed1991

Contribution of the VH11 gene family to mitogen-responsive B cell repertoire in C57BL/6 mice.

The contribution of VH11 gene family to the development of the primary B cell repertoire has been studied by analyzing 1.8 x 10(4) mitogen induced B lymphocyte colonies. The data demonstrate that VH11 family is predominantly expressed among neonatal splenic as well as adult peritoneal B cell colonies, both rich in Ly-1+ B cells. VH11 gene family expression among B splenocytes decreases during ontogeny and VH11 family pairs stochastically with different V kappa families among mitogen-activated neonatal B cell colonies, which are representative of an antigen unselected B cell repertoire. Thus, an increased VH11 expression among peritoneal and neonatal B cells points towards its biased expression among Ly-1+ B lymphocytes. The restricted V gene rearrangements and VH11-V kappa 9 pairing observed among anti-bromelain-treated mouse red blood cells autoantibodies are likely to be an outcome of both intrinsic gene recombination processes per se as well as selection by an autoantigen and/or local selective environmental factors.

Age Factors↗
PubMed1991

Correlation between the occurrence of lupus nephritis, anti-erythrocyte autoantibodies and V kappa haplotype in NZB x 129/J and NZB x SM/J recombinant inbred murine strains.

The NZB mouse is genetically predisposed to the development of autoimmune disease that resembles the human autoimmune systemic lupus erythematosus and autoimmune hemolytic anemia, with increased titers of anti-DNA, and Coombs' autoantibodies. The various autoimmune traits are controlled separately by a limited number of genes. Genetic studies have shown that several immune loci are involved in autoimmunity: T cell abnormalities, H-2 complex and immunoglobulin genes have been implicated. In this report, we present evidence for a significant correlation of NZB V kappa 1 haplotype defined by restriction fragment length polymorphism analysis with anti-erythrocyte autoantibodies in NZB x 129/J and NZB x SM/J recombinant inbred lines.

Animals↗
PubMed1991

Malignant CD5 B cells--biased immunoglobulin variable gene usage and autoantibody production.

Malignant CD5 B cells obtained from patients with chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) were analyzed for immunoglobulin variable gene usage, CD5 gene expression and autoantibody production. A statistically significant biased usage of the VH5, VH6 and VKIII immunoglobulin variable gene families was observed. It is important to point out that both VH5 and VH6 are extremely small families which are located at the 3' extremity of the immunoglobulin variable gene locus. We determined that the transcription of the CD5 gene in T cell malignancies, CLL, SLL and a selected group of EBV transformed lines was identical. Autoantibody production was studied in a panel of heterohybridomas obtained by the fusion of CLL cells with mouse myeloma line SP2/0. A large fraction of these heterohybridomas secrete autoantibodies; some were monospecific, some bispecific and some polyspecific.

Antigens, CD↗
PubMed1990

Identification of a new V kappa gene family that is highly expressed in hybridomas from an autoimmune mouse strain.

We have identified a new murine V kappa family that contains five to seven members, one member of which encodes the L chain V region of an anti-dsDNA antibody produced by a BALB/c hybridoma, C8.5. The cloned C8.5 V kappa gene exhibits highest homology with a human V kappa gene that was cloned from a nonproductive rearrangement but has never been seen in an expressed repertoire. Because this family was first identified in an autoantibody, we studied its expression in an autoimmune mouse strain. This V kappa family is expressed in 20% of hybridomas from NZB mice.

Amino Acid Sequence↗
PubMed1990

V kappa gene usage, idiotype expression, and antigen binding among clones expressing the VHX24 gene family derived from naive and anti-idiotype immune BALB/c mice.

The BALB/c myeloma protein ABPC48 binds beta(2-6)-linked fructosans and expresses genes derived from the VHX24 and V kappa 10 gene families. We have selected 30 hybridomas expressing the VHX24 gene family derived from mitogen-stimulated spleen cells of naive BALB/c mice and mice injected at birth with the syngeneic monoclonal anti-ABPC48Id, IDA10. The majority of mAb with kappa L chains uses V kappa 1. Antibodies reacting with IDA10 use both V kappa 10 and V kappa 1. Most of these VHX24+ mAb reacted with one or more members of a limited panel of predominantly polysaccharide Ag that have been previously observed to interact with antibodies expressing the VHX24 gene family. Nucleotide sequencing of selected VH and V kappa genes shows a very low frequency of somatic mutation. The effect of neonatal anti-Id injection on VHX24-V kappa pairing and Id expression is discussed.

Animals↗
PubMed1990

Autoimmune mice make anti-Fc gamma receptor antibodies.

We demonstrate, using a recombinant truncated Fc gamma RII molecule as a probe, the presence of anti-Fc gamma R antibodies in several strains of autoimmune mice. Affinity chromatography on a truncated Fc gamma R column of pooled sera from aged NZB females resulted in isolation of 16 micrograms of IgM per ml of serum, approximately 2% of the total IgM; no anti-Fc gamma R IgM was found in sera from C58/J mice. Mice with high titers of anti-Fc gamma R IgM also had anti-Fc gamma R IgG. Affinity-purified anti-Fc gamma R IgG bound to Fc gamma R-bearing cells. A good correlation was found between the presence of anti-Fc gamma R Ig and impaired phagocytosis of immune complexes in autoimmune strains such as NZB or NZB/NZW F1. Sera with high titers of anti-Fc gamma R Ig from NZB and motheaten mice inhibited the binding of soluble immune complexes. Furthermore, BXSB, a lupus-prone mouse strain that does not produce anti-Fc gamma R Ig, shows normal macrophage binding and phagocytosis of immune complexes. A set of four IgM mAbs that bind to Fc gamma R was identified. These antibodies were polyspecific; some were directed against DNA, and others recognized a wide variety of antigens including histones, thyroglobulin, and transferrin, but all anti-Fc gamma R IgM antibodies effectively inhibited the binding of IgG1 anti-DNP/DNP20BSA complexes to J774 macrophages. The role of anti-Fc gamma R Ig in autoimmunity remains to be established. It may act to crosslink and activate Fc gamma Rs on neutrophils, macrophages, NK, and mesangial cells, or it may desensitize Fc gamma R function of Fc gamma R-bearing cells.

Aging↗
PubMed1990

A molecular and structural analysis of the VH and VK regions of monoclonal antibodies bearing the A48 regulatory idiotype.

The results presented in this paper explore the molecular basis for expression of the A48 regulatory Id (RI). A48 RI+ mAb derived from idiotypically manipulated mice molecularly resembled the A48 and UPC 10 prototypes of this system by utilizing a VHX24-Vk10 combination. Id expression by these antibodies was not restricted by a particular D region sequence, JH, or JK segment, but quantitative differences in Id expression were associated with utilization of different members of the VK10 germ-line gene families. The VL sequences of these A48 RI+ mAb has identified amino acid residues lying in four different idiotope-determining regions which may contribute to the structural correlate of this Id. A comparative sequence analysis of the VH regions of these VHX24 utilizing A48 RI+ mAb with several A48 RI+ mAb utilizing VHJ558 or VH7183 VH genes as well as a hybrid transfectoma antibody derived from two A48 RI-, VHJ558 utilizing hybridomas, all suggested that four nonconsecutive positions which lie outside the idiotope-determining regions may contribute structural elements toward expression of this Id. The VH and VL regions of the A48RI+, VHX24-Vk 10+ mAb showed low to moderate levels of somatic mutation which showed different patterns of distribution between the complementary determining region (CDR) and framework regions in the H and L chains. Although the VK sequences contained 50% of the replacement mutations in the CDR, with a replacement/silent mutation ratio of 10, the CDR of the VH sequences contained only 31% of the replacement mutations with a replacement/silent mutation ratio of 0.69.

Amino Acid Sequence↗
PubMed1990

Binding specificities of inulin-binding immunoglobulins for sinistrin and oligosaccharides isolated from asparagus roots.

The major aim of this study was to further investigate the fine specificity of myeloma proteins recognizing epitopes on fructans. Our studies showed that UPC 61, EPC 109, and a hybrid antibody composed of the heavy chain from UPC 61 and the light chain from EPC 109, UPC 61H:EPC 109L, not only bind to inulin which is a linear fructan of beta (2----1) fructofuranosyl linkages, but also bind to sinistrin, a branched molecule consisting of a beta (2----1) fructofuranosyl backbone with beta (2----6) branch points. The fine binding specificity of these three antibodies for the beta (2----1) fructofuranosyl linkages found in inulin-BSA can be further studied by their binding to fructan oligosaccharides isolated from asparagus roots. From a comparative analysis of the amino acid sequences and the apparent affinity constants (aKa) of UPC 61, EPC 109, and the hybrid for various fructan oligosaccharides, it appears that the light chain of the immunoglobulin molecule makes an important contribution to the binding specificity. Finally we report for the first time that a monoclonal antibody specific for beta (2----6) fructans can also bind specifically to inulin-BSA with a lower affinity. This antibody derives its VH and VL from the VHX24 and Vk10b gene families, respectively, which are different from the gene families utilized by UPC 61 and EPC 109 (VHJ606 and Vk11 gene families).

Animals↗
PubMed1990

Ly1 and V-gene expression among hybridomas secreting natural autoantibody.

This report presents evidence that multispecific natural autoantibodies (NAAb) arise from both Ly-1+ and Ly-1- B lymphocyte subsets based upon detection of mRNA transcript of Ly1 gene by Northern blotting among hybridomas from several mouse strains. Newborn Xid mice also possess B cells transcribing the Ly-1 gene that secrete multispecific NAAbs. Different VH and VK gene families were expressed at random in both Ly-1+ and Ly-1- hybridoma clones secreting NAAbs. Certain VK gene families VK1, -8, -9, -10 and -19, were preferentially used by NAAbs. No particular VH:VK pairings were observed among NAAbs multispecifically reactive with DNA and cytoskeleton proteins. The NAAbs reactive with BrMRBC exhibited predominant pairing between VH11:VK9 gene families, although, for the first time, we noted the participation of VK1, -10 and -19 gene families in encoding this autoantibody specificity.

Animals↗
PubMed1990

Stochastic pairing of heavy-chain and kappa light-chain variable gene families occurs in polyclonally activated B cells.

Frequencies of 25 immunoglobulin heavy-chain and kappa light-chain variable (VH + V kappa) gene-family pairings expressed in splenic B-cell populations were determined by hybridization of VH- and V kappa-family-specific DNA probes to mitogen-induced B-cell colonies from C57BL/6 mice or hybridomas derived from BALB/c and NZB mice. Both analyses support the conclusion that VH and V kappa gene families pair without bias; as would be expected for random association, the frequencies of specific VH + V kappa pairs may be estimated by the product of the independent VH and V kappa frequencies. Based upon the frequencies at which 9 VH and 12 V kappa gene families are expressed, we calculated the expected usage for approximately 100 VH + V kappa family pairings in neonatal and adult C57BL/6 mice. Variability in the expression of such VH + V kappa pairings is considerable; pairs representing greater than 10% to less than 0.01% of the splenic B-cell population occur. This variability is most pronounced in the neonate, where 6 VH + V kappa family pairs account for nearly 40% of all mitogen-reactive B cells. As the neonate matures, the distribution of frequencies for VH + V kappa pairings becomes more nearly uniform. This process may underlie the patterned acquisition of humoral immune responsiveness.

Animals↗
PubMed1990

The LY-1 gene expression in murine hybridomas producing autoantibodies.

Studies presented here demonstrate the expression of the Ly-1 gene and the detection of the Ly-1 cytodifferentiation antigen in murine hybridomas producing autoantibodies. We examined the transcription of the Ly-1 gene in thymocytes and 140 hybridomas producing autoantibodies of various specificities which were obtained from normal and autoimmune disease prone mouse strains. As previously demonstrated thymocytes stain brightly for Ly-1 by immunofluorescence and express Ly-1 transcripts. In our panel of hybridomas producing autoantibodies Ly-1 transcripts were detected in 31 (45%) out of 69 NZB hybridomas and 7 (88%) out of 8 viable motheaten hybridomas. S1 nuclease protection experiments showed that Ly-1 transcripts detected in thymocytes and B cells are the product of the same gene. The B cell transcripts are functional since immunofluorescence and Western data presented here detected the Ly-1 protein in hybridomas cells which were found to transcribe the Ly-1 gene. Interestingly a polymorphic transcription of the Ly-1 gene was observed in B cells and B cell hybridomas as compared to thymocytes. Our results obtained in the hybridoma system firmly establish a major contribution of the Ly-1 B cell subset to the production of DNA specific autoantibodies and a smaller contribution to the production of rheumatoid factors and "natural", multispecific autoantibodies.

Animals↗