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Biomedical subjects

S K Datta

Publications and source records attributed to S K Datta.

At least 73 records · Page 4Linked to original sources
PubMed1993

Lysis of human arterial smooth muscle cells infected with herpesviridae by peripheral blood mononuclear cells: implications for atherosclerosis.

The cytotoxicity of peripheral blood mononuclear cells (PBMC) to human arterial smooth muscle cells (SMC) infected with cytomegalovirus (CMV) or herpes simplex virus-1 (HSV) was investigated. PBMC were isolated from heparinized blood of healthy donors by Ficoll-Hypaque centrifugation and were tested for cytotoxicity against human SMC or human fibroblast-like (MRC-5) cells infected with CMV or HSV, using the chromium-51 (51Cr) release cytotoxicity assay. Both SMC and MRC-5 cells infected with either CMV (SMC-CMV), (MRC-5-CMV), or HSV (SMC-HSV), (MRC-5-HSV) were lysed by PBMC above background lysis of uninfected SMC cells. Treatment of PBMC with NK-specific monoclonal CD16 antibody and rabbit complement reduced greatly the lysis of SMC, SMC-CMV, and K562 cells, suggesting that lysis of different types of target cell by PBMC was mediated mainly by natural killer (NK) cells. The pattern of natural cytotoxicity against SMC-CMV was different from that against SMC-HSV. Maximum lysis of SMC-CMV was observed at 24 hr postinfection compared to 8 hr postinfection for SMC-HSV. NK reactivity against SMC-CMV increased from 8 to 24 hr postinfection, followed by a gradual decline at 48 and 72 hr. Supernatants generated by culturing SMC-CMV or coculturing SMC-CMV with PBMC enhanced NK cell-mediated lysis of SMC or SMC-CMV. Natural cytotoxic reactivities of PBMC against SMC-CMV or SMC-HSV may occur in vivo. Such reactions could moderate the interaction of these viruses with vascular SMC and could influence the development and/or the progression of atherosclerotic lesions.

Arteriosclerosis↗
PubMed1993

State of the foreign gene and of the genome in transgenic rice (Oryza sativa L.).

PCR with random primers (RAPD analysis) performed on the DNA of embryogenic and non-embryogenic suspension cultured rice and of transformed rice plants allows the evaluation of the extent of DNA changes in the different biological materials. This is thus suggested as a convenient approach, in combination with restriction analysis and Southerns blotting, to evaluate the integrity of the foreign gene, the stability of the insertion site and the stability of the whole genome.

Base Sequence↗
PubMed1992

Cationic residues in pathogenic anti-DNA autoantibodies arise by mutations of a germ-line gene that belongs to a large VH gene subfamily.

The F1 progeny of autoimmune NZB and normal SWR mice uniformly develop severe and accelerated lupus nephritis. The (SWR x NZB)F1 mice produce an oligoclonally expanded population of nephritogenic anti-DNA autoantibodies that share a recurrent cross-reactive idiotype (Id564), use highly homologous VH genes and surprisingly have the CH region allotype of the normal SWR parent. From extensive library analyses, we isolated 15 SWR germ-line genes which are most closely related to the pathogenic autoantibody VH564 gene and which also belong to the NPb subfamily of J558 VH genes. We found that the pathogenic VH genes are probably somatic variants of a SWR germ-line VH gene, SW6-3, and they have several basic amino acid substitutions, in addition to those already present in the SW6-3 germ-line gene. Since these pathogenic autoantibodies are not detectable in the sera of the normal SWR mice despite the presence of the SW6-3 gene, strong selection and expansion of B cells expressing the SW6-3 VH gene is probably occurring in (SWR x NZB)F1 lupus-prone mice. We also isolated eight germ-line genes from the NZB mouse which are homologous to SW6-3. The autoimmune NZB parent that rarely develops nephritis lacks the SW6-3 gene, but has several highly homologous germ-line VH genes that would encode less cationic antibodies. These results establish a correlation between structure and pathogenic potential of VH genes.

Amino Acid Sequence↗
PubMed1992

Herbicide-resistant Indica rice plants from IRRI breeding line IR72 after PEG-mediated transformation of protoplasts.

The commercially important Indica rice cultivar Oryza sativa cv. IR72 has been transformed using direct gene transfer to protoplasts. PEG-mediated transformation was done with two plasmid constructs containing either a CaMV 35S promoter/HPH chimaeric gene conferring resistance to hygromycin (Hg) or a CaMV 35S promoter/BAR chimaeric gene conferring resistance to a commercial herbicide (Basta) containing phosphinothricin (PPT). We have obtained so far 92 Hgr and 170 PPTr IR72 plants from protoplasts through selection. 31 Hgr and 70 PPTr plants are being grown in the greenhouse to maturity. Data from Southern analysis and enzyme assays proved that the transgene was stably integrated into the host genome and expressed. Transgenic plants showed complete resistance to high doses of the commercial formulations of PPT.

Aminobutyrates↗
PubMed1992

Pathogenic autoantibody-inducing gamma/delta T helper cells from patients with lupus nephritis express unusual T cell receptors.

In previous work, we found that only 59 (15%) of 396 "autoreactive" T cell clones derived from five patients with lupus nephritis had the ability to selectively augment the production of pathogenic anti-DNA autoantibodies and the majority (49/59) of those autoimmune T helper (Th) clones were CD4+. Surprisingly, 7 of those Th clones were CD4-/CD8- and gamma/delta TCR+, capable of augmenting the production of pathogenic anti-DNA autoantibodies up to 125-fold. The gamma/delta Th clones responded in a MHC-nonrestricted manner to some endogenous autoantigen associated with heat shock proteins (HSP60) on the lupus B cells. The gamma/delta TCR genes expressed by 4 of these Th clones were amplified and sequenced here. Three of the 4 Th clones, each from a different lupus patient, expressed a gene from the V gamma 1 subgroup. Moreover, 2 of the Th clones expressed V delta 5, and the others V delta 1 or V delta 3. These TCRs are rarely expressed by peripheral blood gamma/delta T cells of normal adult humans. The predominant gamma/delta T cells in human peripheral blood express V gamma 2 (V gamma 9) and V delta 2 TCR genes, including HSP-responsive T cells. None of the lupus Th clones expressed this combination of TCR genes. In addition, some of these pathogenic autoantibody-inducing Th clones from the lupus patients had limited diversity and few N-nucleotide additions in their gamma/delta TCR junctional regions (CDR3), thus resembling fetal gamma/delta thymocytes early in ontogeny.

Base Sequence↗
PubMed1992

Anti-DNA antibodies form immune deposits at distinct glomerular and vascular sites.

To investigate the capacity of lupus autoAb to produce glomerular immune deposits (ID) and nephritis, 24 murine monoclonal (m) anti-DNA antibodies (Ab), derived from either MRL-lpr/lpr, SNF1 or NZB lupus-prone mice and selected based on properties shared with nephritogenic Ig, were administered i.p. (as hybridomas) and i.v. (as purified Ig) to normal mice; at least four mice/mAb were evaluated. Three general patterns of immune deposit formation (IDF) were observed: extracellular ID within glomeruli (+/- blood vessels, N = 8); intranuclear ID (N = 5); or minimal or no ID (N = 11). The four MRL m anti-DNA Ab that produced significant extracellular ID demonstrated different disease profiles including: (a) mesangial and subendothelial ID with anti-basement membrane staining, associated with proliferative glomerulonephritis, PMN infiltration, and proteinuria; (b) diffuse fine granular mesangial and extraglomerular vascular ID, associated with proliferative glomerulonephritis and proteinuria; (c) dense intramembranous ID and intraluminal ID, associated with capillary wall thickening, mesangial interposition and expansion, aneurysmal dilatation and intraluminal occlusion of glomerular capillary loops, and heavy proteinuria; and (d) mesangial and extraglomerular vascular ID, associated with mild segmental mesangial expansion, without proteinuria. These MRL mAb were derived from four different mice, and they had variable pIs and isotypes. They all cross reacted with multiple autoantigens (autoAg), however, their autoAg binding profiles were distinguishable. Among the SNF1 derived mAb, four produced histologically and clinically indistinguishable disease characterized by diffuse mesangial and capillary wall ID, associated with cellular proliferation/infiltration and proteinuria. Three of the four mAb were derived from the same mouse and were clonally related; they were: IgG2b with SWR allotype, relatively cationic, highly cross reactive with similar Ag binding patterns, idiotypically related and encoded by identical VH and nearly identical VL sequences. We conclude that both the capacity of lupus autoAb to form ID and the location of IDF are dependent on properties unique to individual Ig. The results also indicate that the Ag binding region of the autoAb is influential in this process, and they suggest that multiple Ab-Ag interactions contribute to IDF in individuals with lupus nephritis. Furthermore, these observations raise the possibility that the pathologic and clinical abnormalities resulting from these interactions are influenced by the location of IDF, and that the dominant interaction, in a given individual, may be highly influential in the phenotypic expression of nephritis.

Animals↗
PubMed1992

Murine monoclonal anti-DNA antibodies penetrate cells, bind to nuclei, and induce glomerular proliferation and proteinuria in vivo.

The production of relatively high quantities of autoantibodies (autoAb) that react with DNA and other intranuclear antigens is characteristic of individuals with systemic lupus erythematosus and other autoimmune diseases. However, the capacity of these Ab to penetrate cells and induce functional perturbations in vivo is not well appreciated. To address this issue, monoclonal (m) anti-DNA Ab (mAb), derived from MRL-lpr/lpr and (NZB x SWR)F1 mice, were administered to normal mice, and the animals were examined for morphologic and functional abnormalities. A subset of five mAb produced intranuclear immunoglobulin deposits in multiple organs. Intranuclear immunoglobulin deposits were also observed after cross-linking the tissue before direct immunofluorescence and after i.v. injection of F(ab')2 fragments of one anti-DNA Ab. This phenomenon was reproducible and was only associated with this subset of autoAb. Furthermore, intranuclear deposits of anti-DNA Ab within glomeruli were associated with morphologic and functional abnormalities including: hypercellularity, epithelial foot process fusion, new fiber bundle formation within the mesangium suggestive of new collagen synthesis, and proteinuria. These results indicate that a subset of autoAb may penetrate cells in vivo to influence normal cellular and nuclear function and to contribute to functional and pathologic abnormalities in individuals with systemic lupus.

Animals↗
PubMed1991

Junctional region sequences of T-cell receptor beta-chain genes expressed by pathogenic anti-DNA autoantibody-inducing helper T cells from lupus mice: possible selection by cationic autoantigens.

We rescued from the spleens of 10 (SWR x NZB)F1 (SNF1) mice with lupus nephritis the T cells that were activated in vivo and cloned 268 T-cell lines and hybridomas. Only 12% of these T-cell clones had the functional ability to preferentially augment the production of pathogenic anti-DNA autoantibodies. Among these, 16 helper T-cell (Th-cell) clones that were mostly CD4+ and had the strongest autoantibody-inducing ability were analyzed for T-cell receptor (TCR) beta-chain gene usage. Seven of the 16 Th-cell clones expressed beta-chain variable region (V beta) V beta 8 (8.2 or 8.3) genes and three expressed V beta 4, whereas two clones each used a V beta 1 or V beta 2 or V beta 14 gene, suggesting some restriction in TCR gene usage. Although heterogeneous, the V-D-J junctional region sequences of TCR beta-chain genes used by these Th-cell clones invariably encoded one or more negatively charged residues (aspartic or glutamic acid) that had been generated in most cases by unspecified nucleotide (N) additions. Representative pathogenic autoantibody-inducing Th-cell clones could rapidly induce the development of lupus nephritis when injected into young prenephritic SNF1 mice. The pathogenic autoantibody-inducing Th cells expressing the anionic residues in their TCR beta-chain junctions (complementarity-determining region CDR3) were probably selected by some cationic autoantigenic peptide presented by the anti-DNA B cells they preferentially helped. These results offer a clue regarding the nature of the primary autoantigen that may drive the pathogenic autoimmune response in lupus.

Amino Acid Sequence↗
PubMed1990

V region sequences of an idiotypically connected family of pathogenic anti-DNA autoantibodies.

The H and L chain V region sequences of nine anti-DNA mAb that are representative of a pathogenic population of autoantibodies produced by the nephritis prone (SWR x NZB)F1 (SNF1) mice, were determined. These nine anti-DNA autoantibodies were idiotypically connected members of a cross-reactive Id family called the Id564 cluster. Moreover, these autoantibodies were all cationic in charge, IgG2b in isotype, and their H chain C regions had the normal SWR parent's allotype. Although derived from two different SNF1 animals, these pathogenic autoantibodies possessed highly homologous Leader-VH sequences that could account for their idiotypic cross-reactivity. Furthermore, the VH region sequences of these anti-DNA antibodies contained numerous basic residues that could impart their cationic charge. The Leader-VH sequences of these autoantibodies were also highly homologous to that of an anti-NP antibody-related germ-line gene of C57BL/6 mice, called VH-23. Among these nine pathogenic autoantibodies, three sets of clonally related anti-DNA antibodies could be identified. Thus the Id564 cluster of cationic anti-DNA autoantibodies of SNF1 mice are encoded by highly related VH genes, and this idiotypically connected population of pathogenic autoantibodies are selected to undergo an oligoclonal expansion in the lupus-prone SNF1 mice.

Amino Acid Sequence↗
PubMed1990

Recognition efficiency of Dicotyledoneae-specific promoter and RNA processing signals in rice.

Heterologous gene expression experiments have shown that genes of Monocotyledoneae are often not transcribed in Dicotyledoneae, or produce pre-mRNA that is inefficiently or aberrantly processed. It is however not known how correctly and efficiently dicotyledon-specific gene expression signals are recognized in cells of Monocotyledoneae. Here we address this question using tobacco (Nicotiana tabacum) and rice (Oryza sativa) protoplasts transformed with the same hybrid gene constructs. Constructs including the nptII protein coding sequence fused to Cauliflower Mosaic Virus (CaMV) promoter and polyadenylation signals were used to obtain stably transformed cell lines of tobacco and rice. In one of the constructs the nptII coding region is interrupted by a modified intron-3 sequence from the soybean phaseolin gene. Although the mean number of hybrid gene copies integrated into the rice genome was on average 5- to 10-fold higher than in tobacco, the steady-state transcript level was 3 times lower. A lower level of transcript was also observed in transient expression experiments. The amount of the mature mRNA was not influenced by the presence of the intron. The phaseolin intron was processed in rice with high efficiency and an accuracy indistinguishable from that seen in tobacco.

Base Sequence↗
PubMed1990

Pathogenic anti-DNA autoantibody-inducing T helper cell lines from patients with active lupus nephritis: isolation of CD4-8- T helper cell lines that express the gamma delta T-cell antigen receptor.

The antigen responsible for autoimmunization in systemic lupus erythematosus is unknown. In spite of this obstacle, we show that T helper (Th) cell lines that are functionally relevant to this disease can be established in vitro. We derived a total of 396 interleukin 2-dependent T-cell lines from the in vivo activated T cells of five patients with lupus nephritis. Only 59 (approximately 15%) of these lines had the ability to selectively augment the production of pathogenic anti-DNA autoantibodies that were IgG in class, cationic in charge, specific for native DNA, and clonally restricted in spectrotype. Forty-nine of these autoantibody-inducing Th lines were CD4+ and expressed the alpha beta T-cell receptor (TCR). The other 10 were CD4-8- (double negative), 3 expressing the alpha beta TCR and 7 expressing the gamma delta TCR. All of the autoantibody-inducing Th lines responded to some endogenous antigen presented by autologous B cells. The autoreactive responses of the CD4+ Th lines were restricted to HLA class II antigens, whereas those of the double-negative cells were not. Endogenous heat shock or stress proteins of the HSP60 family that were expressed by the lupus patients' B cells were involved in stimulating an autoreactive proliferation of the gamma delta Th cells. These studies demonstrate a novel helper activity of certain gamma delta T cells in a spontaneous autoimmune response.

Antibodies, Monoclonal↗
PubMed1990

Selective strain distribution pattern of a germline VH gene for a pathogenic anti-DNA autoantibody family.

Autoimmune NZB mice rarely develop nephritis, but the SNF1, progeny of Crosses between NZB and the normal SWR strain uniformly develop severe lupus nephritis, indicating that the normal SWR strain makes a genetic contribution to the development of nephritis. The SNF1 mice produce a select population of cationic IgG anti-DNA autoantibodies that share a recurrent cross-reactive idiotype called Id564 and these autoantibodies play a prominent role in the development of nephritis. These pathogenic autoantibodies of SNF1 possess the IgCH allotype of the SWR, indicating their origin from the normal parent. The leader-VH sequences of these Id564+ pathogenic anti-DNA autoantibodies are highly homologous and they are also related by 95% homology to a germline gene of normal C57BL/6 mice, called VH-23, that is a member of an anti-NP antibody gene family. Herein, we cloned the flanking and coding regions of the expressed VHDJH genes of the anti-DNA mAb 564, the prototype member of the pathogenic Id564 family. By restriction analysis and partial sequencing, we found that the VH564 gene is related but distinct in its 5' flanking region from all of the known anti-NP VH genes of C57BL/6 and BALB/c mice. Hybridization with four probes complementary to different segments of the flanking and coding regions of the expressed VH564 gene indicated that the germline gene for VH564 is contained in an approximately 5.2 kb EcoRI fragment of SWR genomic DNA. Moreover, high stringency hybridization with oligonucleotide probes complementary to unique CDR2 and 5' flanking sequences of the expressed VH564 gene revealed that the 'approximately 5.2 kb' germline allele for VH564 that is possessed by the normal SWR parental strain is lacking in the NZB parental strain. C57BL/6 mice also lack this allele of the anti-DNA VH564 germline gene, although this strain possesses the highly homologous, anti-NP-related VH-23 germline gene. Thus germline VH genes for certain pathogenic autoantibodies may have a selective strain distribution pattern.

Alleles↗
PubMed1989

T cell receptor alpha/beta expressing double-negative (CD4-/CD8-) and CD4+ T helper cells in humans augment the production of pathogenic anti-DNA autoantibodies associated with lupus nephritis.

It is generally accepted that human Th cells express the surface glycoproteins CD4 and alpha/beta-chain heterodimer of the TCR whereas cytotoxic/suppressor cells are usually CD8+ and alpha/beta TCR+. Another minor set of T cells found in the periphery are CD4-/CD8- (double negative) and express the gamma/delta TCR; these cells can manifest MHC-restricted or nonrestricted cytotoxicity but no helper function. Herein we describe the existence of an unusual Th population in the peripheral blood of humans that are CD4-/CD8- and alpha/beta TCR+. These double-negative Th were markedly expanded in patients with the autoimmune disease SLE and along with CD4+ Th, they induced production of the pathogenic variety of anti-DNA autoantibodies that are IgG in class and cationic in charge. The cationic anti-DNA antibodies induced by the Th were markedly restricted in spectrotype indicating that an oligoclonal population of B cells were committed to produce the pathogenic autoantibodies in active lupus. IL-2-dependent T cell lines were also derived from the patients with active lupus nephritis but the majority of those T cell lines lacked pathogenic autoantibody-inducing capability. Only 4 out of 42 T cell lines from a lupus patient could induce the production of cationic IgG class anti-DNA autoantibodies. The phenotypes of the pathogenic autoantibody-inducing Th lines were similar to the Th subsets: CD4+, alpha/beta TCR+ or CD4-/CD8-, alpha/beta TCR+. These studies suggest that production of pathogenic autoantibodies in human lupus is mediated by mechanisms that are distinct from the generalized, nonspecific polyclonal B cell hyperactivity that leads to excessive production of natural autoantibodies.

Adult↗
PubMed1988

CD4+ T cell lines with selective patterns of autoreactivity as well as CD4- CD8- T helper cell lines augment the production of idiotypes shared by pathogenic anti-DNA autoantibodies in the NZB x SWR model of lupus nephritis.

The (NZB x SWR)F1 hybrid mice (SNF1) uniformly develop lethal glomerulonephritis in marked contrast to their parents and produce nephritogenic autoantibodies that consist of highly cationic, IgG anti-DNA antibodies that share distinct cross-reactive idiotypes called IdLNF1 (idiotypes-lupus nephritis-SNF1). Herein we found that spleen cells of SNF1 mice at the late prenephritic stage, contained CD4+/CD8- and CD4-/CD8- Th that not only induced their B cells in vitro to produce highly cationic IgG autoantibodies to DNA but IdLNF1-positive IgG antibodies as well. The double-negative Th were unexpected in the SNF1 mice because they lack the lpr (lymphoproliferation) gene. We also derived IL-2-dependent CD4+/CD8- as well as CD4-/CD8- T cell lines from nephritic SNF1 mice, that could simultaneously induce IdLNF1-positive and cationic anti-DNA antibodies of IgG class. The CD4+ T cell lines consisted of "autoreactive" T cells, but not all of the lines were equal in autoantibody-inducing capability. Remarkably, the T cell lines that preferentially responded to F1-hybrid-MHC determinants, had a significantly greater ability to augment the production of pathogenic autoantibodies. The SNF1-Th could also augment autoantibody production by the NZB or SWR parent's B cells; however, IdLNF1-positive and cationic anti-DNA autoantibodies of IgG class were not induced, suggesting that the SNF1 mice possess a select population of inducible (susceptible) B cells that are committed to produce nephritogenic autoantibodies and the parental strains are deficient in such B cells. Thus, production of nephritogenic autoantibodies with IdLNF1 markers in the SNF1 mice could result from an interaction between a select population of B cells and CD4+ Th that preferentially recognize unique F1-hybrid-MHC determinants, as well as double-negative auxiliary Th.

Animals↗
PubMed1988

Murine lupus.

In mice with lupus nephritis qualitative changes in anti-DNA antibodies occur, such as IgG switch and increased cationic charge, to render these antibodies pathogenic. Pathogenic anti-DNA idiotypes can be encoded by genes of a normal mouse strain such as SWR, where they remain dormant. When the normal mice are crossed with an autoimmune strain like NZB, the F1 hybrids express these idiotypes owing to defects in immunoregulation, resulting in the development of lethal glomerulonephritis.

Animals↗