Biomedical subjects

T F Tedder

Publications and source records attributed to T F Tedder.

At least 163 records · Page 9Linked to original sources

PubMed1990

Human antigen-specific memory T cells express the homing receptor (LAM-1) necessary for lymphocyte recirculation.

Lymphocytes must circulate from blood into lymphoid tissues and sites of infection and inflammation to function efficiently in vivo. This process of "homing" is in part directed by the expression of the leukocyte adhesion molecule (LAM-1, also known as TQ1 and Leu-8) in humans and the homologous MEL-14 antigen in mice. In this report, we demonstrate that the LAM-1 molecule is a 74-kDa protein and that only half of the CD4+ T cells in humans which have a memory phenotype (CD45RA -CD29hi) express the LAM-1 molecule. Functionally, these two phenotypically distinct subpopulations of memory cells were quite different. The LAM-1+ memory cells proliferated better to recall antigen and induced three to seven times higher levels of B cell immunoglobulin secretion than their LAM-1- counterparts. Thus, antigen-specific memory T cells within the helper lineage express the homing receptor appropriate for regulating their migration to secondary lymphoid tissues and sites of inflammation.

B-Lymphocytes↗

PubMed1990

The role of functionally distinct helper T lymphocyte subpopulations in the induction of human B cell differentiation.

Human helper T lymphocytes can be dissected into two functionally distinct subpopulations based on expression of the CD45RA (2H4) or CD45R0 (UCHL-1) surface antigens. While both subpopulations are able to induce equivalent levels of B cell activation and proliferation, only the CD4+CD45RA- subpopulation is capable of inducing B cell differentiation in pokeweed mitogen (PWM)-stimulated cultures. To define the mechanism responsible for the dichotomy between induction of proliferation and differentiation by the two CD4+ subpopulations, we examined the abilities of the purified T cell subpopulations to produce lymphokine mRNA following T cell activation. Northern analysis revealed that both subpopulations produced interleukin (IL) 2 and interferon (IFN)-gamma mRNA following PWM activation. The CD4+CD45RA- subpopulation, however, produced higher levels of IFN-gamma mRNA and the CD4+CD45RA+ cells produced higher levels of IL 2 mRNA. Neither subpopulation elaborated detectable mRNA for IL 4, IL 5 or IL 6. Of greatest significance was that the addition of recombinant or T cell-derived lymphokines could not compensate for the inability of the CD4+CD45RA+ subpopulation to induce B cell differentiation in PWM assays. Direct T-B cell contact was required for the optimal induction B cell differentiation in these assays, suggesting that CD4+CD45RA+ T cells were deficient in their ability to directly deliver the T cell-B cell signals required for B cell differentiation. These results suggest that the differential ability of the two subpopulations of CD4+ T cells to induce B cell differentiation does not result from differences in lymphokines elaborated, but may result from differences in their abilities to interact directly with B cells to initiate differentiation.

Antigens, CD↗

PubMed1990

Combined immunodeficiency due to the selective absence of CD4 inducer T lymphocytes.

Selective congenital deficiency of the CD4 inducer T lymphocyte subset is a recently described variant of combined immunodeficiency. To further characterize the cellular and molecular mechanisms which lead to the profound T and B cell immunodeficiency in this condition, we examined in vitro immunoregulatory T lymphocyte activation and effector function, interleukin-2 (IL-2) synthesis, IL-2 receptor generation, and CD4 gene structure. Immunophenotyping of T lymphocytes demonstrated a selective deficiency of CD4+ cells, with normal numbers of CD2+ and CD3+ T cells, nearly all of which expressed the CD8+ determinant. Mitogen- and alloantigen-induced blastogenesis was profoundly decreased. B lymphocytes were present in normal numbers but there was a functional dysgammaglobulinemia (low IgG, normal IgM, low IgA) with no antibody response to in vivo immunization. T cells from the patient did not provide help to normal B cells for in vitro immunoglobulin synthesis; however, the patient's B cells were capable of synthesizing normal amounts of IgG when provided help from normal T cells. Concanavalin A failed to activate suppressor-inducer function in the patient's T cells. However, CD8+ T cell-mediated suppression was expressed if the patients T cells were cocultured with normal CD4+ T cells in a pokeweed mitogen-stimulated IgG secretion assay. IL-2 secretion and IL-2 receptor expression were both markedly reduced. Southern blot analysis of genomic DNA revealed no obvious abnormality in CD4 gene structure. The global defects in T cell activation, effector function, immunoregulation, and lymphokine generation observed in CD4+ inducer lymphocyte deficiency emphasizes the central role that the CD4 T lymphocyte plays in the activation and regulation in vivo immune responses.

B-Lymphocytes↗

PubMed1989

Isolation of cDNAs encoding the CD19 antigen of human and mouse B lymphocytes. A new member of the immunoglobulin superfamily.

The CD19 (B4) molecule is a m.w. 95,000 cell-surface protein of human B lymphocytes that is expressed before Ig and persists throughout differentiation. In this report, cDNA clones that encode the CD19 molecule were isolated and the amino acid sequence of CD19 was determined. A cDNA clone that selectively hybridized to RNA from CD19+ cell lines was selected from a human tonsilar cDNA library using differential hybridization. This cDNA was used to isolate additional cDNA clones. Four of the five longest cDNA clones isolated were sequenced and found to contain unique sequences presumed to be introns. One clone, pB4-19, was near full length (2.1 kb) and did not contain these putative introns. pB4-19 contained an 1685 bp open reading frame that could encode a protein of about 60 kDa. COS cells that were transfected with pB4-19 expressed a nascent cell surface structure reactive with the anti-B4 antibody. Immunoprecipitation of this structure from surface-iodinated COS cells with the anti-B4 antibody revealed a m.w. 85,000 protein. Northern blot analysis indicated that pB4-19 hybridized with a predominant mRNA species of 2.4 kb and a minor species of 1.5 kb, found in only CD19+ cells. The pre-B cell line, PB-697, also expressed four larger RNA species that hybridized with pB4-19. cDNA clones that encode the putative cytoplasmic portion (247 amino acids) of the mouse CD19 molecule were also isolated and found to be highly homologous (79 and 75%) with the human CD19 nucleotide and amino acid sequences. The deduced amino acid sequence of the CD19 cytoplasmic tail shared no significant homology with other known proteins but the putative extracellular region contained two Ig-like domains indicating that CD19 is a new member of the Ig superfamily.

Amino Acid Sequence↗

PubMed1989

Isolation and chromosomal localization of cDNAs encoding a novel human lymphocyte cell surface molecule, LAM-1. Homology with the mouse lymphocyte homing receptor and other human adhesion proteins.

A cDNA encoding a new human lymphocyte cell surface molecule has been isolated and shown to identify a fourth member of a recently discovered family of adhesion proteins. This lymphocyte-associated molecule (LAM-1) is uniquely composed of multiple distinct domains, one domain homologous with animal lectins, one homologous with epidermal growth factor, and two short consensus repeat units similar to those found in C3/C4 binding proteins. This cDNA clone hybridized with RNAs found in B cell lines and T lymphocytes, but not with RNA from other cell types. The amino acid sequence of LAM-1 is 77% homologous with the sequence of the mouse lymphocyte homing receptor, suggesting that LAM-1 may function in human lymphocyte adhesion. The LAM-1 gene is located on chromosome 1q23-25, as is another member of this adhesion family, suggesting that this new family of proteins may be encoded by a cluster of "adhesion protein" loci.

Amino Acid Sequence↗

PubMed1989

The gene that encodes the human CD20 (B1) differentiation antigen is located on chromosome 11 near the t(11;14)(q13;q32) translocation site.

The human CD20 gene (B1) encodes a B lymphocyte-specific, cell-surface molecule that is involved in B cell activation and differentiation. We report that the CD20 gene is located on human chromosome 11 at position q12-q13. The location of CD20 was determined by in situ hybridization and was further confirmed by Southern blot analysis of DNA from rodent/human hybrids that contained only portions of human chromosome 11. This localization places the CD20 gene near the site of the t(11;14)(q13;q32) translocation that is found in a subgroup of B cell-lineage malignancies. The site of this translocation has been previously identified by DNA cloning and termed bcl-1. The CD20 gene was found to lie on the centromeric side of bcl-1 on chromosome 11 and to be separated from bcl-1 by at least 50 kb of DNA. These results raise the possibility that alterations in the expression of the CD20 gene may result after the t(11;14) chromosomal alteration.

Animals↗

PubMed1989

Structure of the gene encoding the human B lymphocyte differentiation antigen CD20 (B1).

The CD20 (B1) molecule is a differentiation Ag found only on the surface of B lymphocytes. This structurally unique phosphoprotein plays a role in the regulation of human B cell proliferation and differentiation. In this report genomic DNA clones containing the human CD20 gene were isolated and the structure of the CD20 gene determined. Southern blot analysis revealed that CD20 mRNA was transcribed from a single-copy gene. The CD20 gene was 16 kb long and was composed of eight exons. The first exon marked the major transcription initiation site as determined by primer extension and S1 nuclease analysis. The translation initiation codon was located within the third exon. Exon VIII encoded the COOH terminus of the CD20 protein and the long 3' untranslated region. Three forms of CD20 mRNA were identified that all encode an identical protein product. The dominant form of 2.8 kb results from usage of exons I through VIII, whereas a second form that is 263 bp shorter had exon I spliced into an internal 3' splice site within exon III thereby skipping exon II. A minor 3.4-kb mRNA species most likely results from an uncharacterized upstream exon(s) splicing into an internal 3' slice site located in exon I. Nucleotide sequences of cDNA clones representative of each of these RNA forms are presented. The 5' splice site following exon V was found to be divergent from the consensus splice sequence. A relationship between the individual peptides encoded by the six exons and structurally distinct regions of the CD20 protein is likely.

Amino Acid Sequence↗

PubMed1989

Amplification of suppressor inducer pathway with monoclonal antibody, anti-2H4, identifying a novel epitope of the common leukocyte antigen/T200 antigen.

The 2H4 antigen, comprised of a 200/220-kDa glycoprotein of the leukocyte common antigen (LCA) family, is expressed on a suppressor inducer, but not a helper inducer subset of T4 cells. Earlier studies have demonstrated that the T4+2H4+ subset of cells maximally responded to the AMLR and this molecule has an important role in generated suppressor signals in AMLR/Con A-activated T cell systems. In the present study, we examined the effect of a series of monoclonal antibodies including anti-2H4 antibody on the initial activation of T4 cells in response to self-Ia antigens. We found that the addition of anti-2H4 antibody resulted in an augmentation of the proliferative response of T4 cells in AMLR, whereas other antibodies reactive with LCA/T200 antigens lacked this ability. Furthermore, anti-2H4 antibody enhanced both IL-2 production and IL-2R expression in this AMLR system. This enhancing effect was inhibited by anti-T3 antibody. Moreover, the suppressor inducer function of AMLR T4 cells was enhanced with anti-2H4 antibody by increasing the number of 2H4+ cells with high antigen density. Taken together, these results suggest that the 2H4 antigen may serve as an accessory structure for enhancing the activation of the T4+2H4+ suppressor inducer subset at initiation of cell triggering.

Antibodies, Monoclonal↗

PubMed1988

Cloning of a complementary DNA encoding a new mouse B lymphocyte differentiation antigen, homologous to the human B1 (CD20) antigen, and localization of the gene to chromosome 19.

The human B1 (CD20) molecule is a differentiation Ag found only on the surface of B lymphocytes. This structurally unique phosphoprotein plays a role in the regulation of human B cell proliferation and differentiation. In order to determine whether this structure is also expressed by murine B cells, cDNA clones that encode the mouse equivalent of the B1 molecule were isolated. The longest murine cDNA clone isolated, pmB1-1, contained a 1.4-kb insert with an 873 base pair open reading frame that encodes a protein of 32 kDa. The predicted mouse B1 protein contains three hydrophobic domains that may span the membrane four times and shares a 73% amino acid sequence homology with the human B1 protein. The pmB1-1 cDNA probe was used to examine mB1 mRNA expression. Northern blot analysis indicated that pmB1-1 hybridized with two mRNA species of 2.3 and 3.0 kb that were expressed only in murine spleen lymphocytes, in B lineage cell lines representing mature B cells, and were weakly expressed in one of two plasmacytoma cell lines. pmB1-1 failed to hybridize with RNA isolated from murine T cell lines, thymus, and nonlymphoid tissues. Southern blot analysis indicated that mB1 was encoded by a single copy gene. In situ hybridization localized the mB1 gene to chromosome 19 band B, a region that also contains the genes that encode the Ly-1, Ly-10, and Ly-12 Ag. These results suggest that only B cells express this heretofore undescribed murine cell-surface protein that is structurally homologous with the membrane-embedded human B1 Ag.

Amino Acid Sequence↗

PubMed1988

Phosphorylation of the B1 (CD20) molecule by normal and malignant human B lymphocytes.

The B1 molecule (CD20) is a phosphoprotein found only on B lymphocytes. Multiple isoforms of the B1 molecule are expressed with Mr of 33,000, B1(33) and Mr of 34,500-36,000, B1(35). In this study it was found that nonproliferating B cells did not incorporate 32PO4 into B1 although phosphorylated class I histocompatibility molecules were easily detected. In contrast B1 isolated from proliferating or malignant B cells or B cell lines was heavily phosphorylated. Cross-linking B1 on the cell surface by antibody resulted in enhanced phosphorylation of B1 as did exposure to phorbol esters, and the membrane permeable diacylglycerol analog 1,2,-dioctanoylglyceron. B1(33) and B1(35) produced identical peptide maps following limited proteinase digestion. However, B1(35) contained both phosphoserine and phosphothreonine, while B1(33) only contained phosphoserine. In addition alkaline phosphatase was able to remove the phosphate residue(s) that resulted in generation of the B1(35) form of B1 but was unable to remove the phosphorylation of B1(33). These results suggest that phosphorylation of B1 molecules is associated with proliferation and that the different Mr forms of B1 result from the phosphorylation of B1 at different sites. Also, the finding that antibody binding to B1 generated a transmembrane signal may explain why antibody binding to B1 alters B cell function.

Antibodies↗

PubMed1988

Branhamella catarrhalis activates human B lymphocytes following interactions with surface IgD and class I major histocompatibility complex antigens.

Branhamella catarrhalis initiated DNA synthesis in human blood or spleen cells enriched for B lymphocytes but did not activate T-lymphocyte-enriched fractions. Monoclonal antibodies were used to determine which B-cell surface molecules were of importance for the activation signal. The addition of monoclonal antibodies reactive with IgD, HLA class I antigens, and B2-microglobulin to B lymphocyte cultures selectively inhibited the B-lymphocyte response to B. catarrhalis. Antibody binding to IgD and class I antigens did not inhibit B-cell proliferation following stimulation with anti-IgM beads, Staphylococcus aureus, or Epstein-Barr virus. This suggests that surface IgD is of major importance for B-lymphocyte stimulation by B. catarrhalis. Since B. catarrhalis binds HLA-ABC containing liposomes it is suggested that a similar binding of B. catarrhalis to HLA-ABC on the surface of B lymphocytes serves as an accessory factor that stabilizes the binding of B. catarrhalis to surface IgD. Activation of human B lymphocytes by B. catarrhalis resulted in changes of cell surface molecules that were quantitatively and qualitatively similar to those that resulted from the activation by S. aureus. Therefore although these two bacteria appear to activate B cells in a similar manner, they induce B-cell proliferation through interactions with different cell surface structures.

Adult↗

PubMed1988

Heterogeneity in the B1 (CD20) cell surface molecule expressed by human B-lymphocytes.

The B1 molecule (CD20) is a phosphoprotein expressed only by B-lymphocytes. In this study, analysis of B1 immunoprecipitated from surface iodinated B-cell lines and B-lymphocytes has shown that there are several expressed forms of B1. A predominant species of Mr 33,000 represents 75-80% of the iodinated cell surface B1 and a Mr 35,000 species represents 20-25%. Limited proteinase digestion of these two species generated similar peptide maps demonstrating that the different forms of B1 shared common peptides. Biosynthetic labeling with [35S]methionine revealed that the Mr 35,000 B1 species may actually represent two bands of Mr 34,500 and 36,000. Endoglycosidase digestion studies and metabolic labeling in the presence of tunicamycin indicated that neither the Mr 33,000 or 34,500-36,000 forms of B1 were glycosylated. The Mr 33,000 and 34,500-36,000 forms of B1 were constitutively phosphorylated in B-cell lines. However, exposure of B-cells to PMA resulted in a significant increase in the phosphorylation of the Mr 34,500-36,000 form. Exposure to PMA also resulted in an increase in the amount of Mr 34,500-36,000 protein immunoprecipitated from 35S labeled cells. These results suggest that there are multiple forms of the B1 molecule expressed by B-lymphocytes and that this heterogeneity may result from phosphorylation of the B1 protein.

Antigens, CD20↗

PubMed1988

Isolation and structure of a cDNA encoding the B1 (CD20) cell-surface antigen of human B lymphocytes.

The B1 (CD20) molecule is a Mr 33,000 phosphoprotein on the surface of human B lymphocytes that may serve a central role in the humoral immune response by regulating B-cell proliferation and differentiation. In this report, a cDNA clone that encodes the B1 molecule was isolated and the amino acid sequence of B1 was determined. B-cell-specific cDNA clones were selected from a human tonsillar cDNA library by differential hybridization with labeled cDNA derived from either size-fractionated B-cell mRNA or size-fractionated T-cell mRNA. Of the 261 cDNA clones isolated, 3 cross-hybridizing cDNA clones were chosen as potential candidates for encoding B1 based on their selective hybridization to RNA from B1-positive cell lines. The longest clone, pB1-21, contained a 2.8-kilobase insert with an 891-base-pair open reading frame that encodes a protein of 33 kDa. mRNA synthesized from the pB1-21 cDNA clone in vitro was translated into a protein of the same apparent molecular weight as B1. Limited proteinase digestion of the pB1-21 translation product and B1 generated peptides of the same sizes, indicating that the pB1-21 cDNA encodes the B1 molecule. Gel blot analysis indicated that pB1-21 hybridized with two mRNA species of 2.8 and 3.4 kilobases only in B1-positive cell lines. The amino acid sequence deduced from the pB1-21 nucleotide sequence apparently lacks a signal sequence and contains three extensive hydrophobic regions. The deduced B1 amino acid sequence shows no significant homology with other known proteins.

Amino Acid Sequence↗

PubMed1987

Preexposure of resting B cells to interferon-gamma enhances their proliferative response to subsequent activation signals.

In this report we demonstrate that pretreatment of resting splenic B cells with IFN-gamma increases their mitogenic response to subsequent activating stimuli. This effect is completely blocked by neutralizing anti-IFN-gamma antibodies. By contrast, a similar effect induced by partially purified BCGF is not completely inhibited by anti-IFN-gamma antibody, inferring that as in the mouse, a B-cell-specific factor may also induce increased responsiveness to mitogens in resting B cells. The mechanism of this response was analyzed. Phenotypic and cell cycle analyses of the IFN-gamma-treated cells following activation were not significantly different from control cells with respect to kinetics, although as expected from thymidine uptake, more cells were actively cycling. Even when a very early manifestation of cell activation, Ca2+ flux was examined, no response to IFN-gamma alone was evoked, and the response to subsequent activation was identical to that of control cells. These data show that IFN-gamma did not directly activate B cells, but primed B cells in a manner which amplified subsequent mitogenesis.

Antibodies, Anti-Idiotypic↗

PubMed1987

Human epithelial cell expression of an Epstein-Barr virus receptor.

Cultured human epithelium bound and internalized radiolabelled Epstein-Barr virus (EBV) within 1 h of exposure. A similar percentage of cultured cells also were reactive with monoclonal antibodies to the EBV/C3d receptor of B lymphocytes. In cross-sections of fresh frozen, stratified epithelium, receptor expression seemed limited to the less differentiated subpopulation of cells. These findings support the notion of direct infection of epithelial cells by EBV and suggest a viral life cycle in epithelium dependent on the stage of cell differentiation.

Cell Line↗

PubMed1987

4-Quinolone drugs affect cell cycle progression and function of human lymphocytes in vitro.

Most antibacterial agents do not affect human lymphocyte function, but a few are inhibitory. In contrast, a pronounced increase in the incorporation of [3H]thymidine in the presence of 4-quinolones was observed in these studies. The uptake of [3H]thymidine into DNA (trichloroacetic acid precipitable) was significantly increased in phytohemagglutinin-stimulated human lymphocytes when they were exposed to eight new 4-quinolone derivatives, ciprofloxacin, norfloxacin, ofloxacin, A-56619, A-56620, amifloxacin, enoxacin, and pefloxacin, at 1.6 to 6.25 micrograms/ml for 5 days. Four less antibacterially active 4-quinolones (nalidixic acid, cinoxacin, flumequine, and pipemidic acid) stimulated [3H]thymidine incorporation only at higher concentrations or not at all. Kinetic studies showed that incorporation of [3H]thymidine was not affected or slightly inhibited by ciprofloxacin 2 days after phytohemagglutinin stimulation but was increased on days 3 to 6. The total incorporation of [3H]thymidine from day 1 to day 6 after phytohemagglutinin stimulation was increased by 42 to 45% at 5 to 20 micrograms of ciprofloxacin per ml. Increased [3H]thymidine incorporation was also seen when human lymphocytes were stimulated with mitogens other than phytohemagglutinin. Ciprofloxacin added at the start of the culture had a more pronounced effect on [3H]thymidine incorporation than when added later. In spite of the apparent increase in DNA synthesis, lymphocyte growth was inhibited by 20 micrograms of ciprofloxacin per ml, and cell cycle analysis showed that ciprofloxacin inhibited progression through the cell cycle. In addition, immunoglobulin secretion by human lymphocytes stimulated by pokeweed mitogen for Epstein-Barr virus was inhibited by approximately 50% at 5 micrograms of ciprofloxacin per ml. These results suggest that the 4-quinolone drugs may also affect eucaryotic cell function in vitro, but additional studies are needed to establish an in vivo relevance.

Anti-Infective Agents↗

PubMed1987

Effects of ciprofloxacin on eucaryotic pyrimidine nucleotide biosynthesis and cell growth.

Several of the new 4-quinolones significantly increase the incorporation of [3H]thymidine into the DNA of mitogen-stimulated human lymphocytes. This study suggests that ciprofloxacin inhibits de novo pyrimidine biosynthesis, thereby resulting in a compensatory increase in the uptake of pyrimidine precursors through salvage pathways, and that additional effects may affect eucaryotic cell growth. Incorporation of deoxyuridine, uridine, and orotic acid as well as thymidine was increased in the presence of ciprofloxacin, one of the antibacterially most active of the new 4-quinolones. In contrast, the uptake was decreased in very high concentrations of the drug. Culture in HAT (hypoxanthine, aminopterine, thymidine) medium, which blocks de novo thymidylate synthesis, abrogated the increase in [3H]thymidine incorporation induced by ciprofloxacin. Ciprofloxacin also failed to increase the uptake of [14C]hypoxanthine or leucine, indicating a selective effect on pyrimidine and not on purine nucleotide biosynthesis. N-(Phosphonacetyl)-L-aspartate, an inhibitor of pyrimidine nucleotide biosynthesis, also increased [3H]thymidine incorporation in phytohemagglutinin-stimulated lymphocytes in a fashion similar to ciprofloxacin. The growth of several cell lines was partially inhibited by ciprofloxacin at 20 micrograms/ml and completely inhibited at 80 to 160 micrograms/ml. Growth inhibition by ciprofloxacin could not be restored by the addition of uridine to the medium. Chromosome breaks, gene amplification, or other genetic alterations could not be detected in human lymphocytes incubated with up to 25 micrograms of ciprofloxacin per ml.

Animals↗

PubMed1987

Novel type of proliferating lymphoplasmacytoid cell with a characteristic spotted immunofluorescence pattern.

We examined bone marrow from myeloma patients for the presence of cells with the characteristics of the clonogenic cell in the myeloma stem cell assay. We identified a novel type of cell that contained cytoplasmic immunoglobulin of the relevant idiotype located in a cytoplasmic spot. This "spotted" Ig could be located in the rough endoplasmic reticulum. Spotted cells are highly proliferative, as evidenced by the nuclear staining with the antibody Ki67, and were found in the bone marrow from most of the myeloma patients studied. This type of cell was also present in patients with immunocytomas, in some cases of benign monoclonal gammopathy, and in patients in the state of polyclonal hypergammaglobulinemia. IgG subclass distribution of so-called spotted cells and plasma cells, found in a patient with pseudo biclonal gammopathy, indicates that spotted cells are intermediate between B cells and plasma cells. Spotted cells express the B cell-associated antigens HB4 and HB6 but do not express other B cluster of differentiation antigens or plasmacytoid antigens tested.

Adult↗