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R L Coffman

Publications and source records attributed to R L Coffman.

At least 163 records · Page 9Linked to original sources
PubMed1986

Analysis of neoplasms induced by Cas-Br-M MuLV tumor extracts.

Cas-Br-M is an ecotropic murine leukemia virus isolated from wild mice that induces a wide spectrum of hematopoietic neoplasms, including T and B cell lymphomas, myelogenous leukemias, and erythroleukemias. The purpose of this study was to determine if the induction of neoplasms belonging to multiple lineages was due to the ecotropic virus itself or to the generation of cell lineage-specific recombinant viruses. The results demonstrate that in some instances (two of 12 tumor extracts tested), recombinant viruses can be recovered from primary Cas-Br-M-induced tumors that will induce lymphomas of single lineages in mice inoculated as newborns. One of these viruses is a recombinant mink cell focus-forming virus that induces T cell lymphomas, and the other is a replication-defective, fibroblast-transforming virus that induces early B lineage lymphomas in mice. Histologic and flow microfluorometric cell surface antigen analyses of primary and in vitro adapted tumors are presented in support of a modified scheme of hematopoietic cell development.

Animals↗
PubMed1986

B cell stimulatory factor-1 enhances the IgE response of lipopolysaccharide-activated B cells.

Supernatants from some mouse helper T cell (TH) lines contain an activity that can enhance IgE production by lipopolysaccharide (LPS)-stimulated B cells by at least two orders of magnitude. During purification, this activity could not be resolved from B cell stimulatory factor-1 (BSF-1). Highly purified BSF-1 from a different source, the T lymphoma cell line EL-4, enhanced IgE production to the same extent as TH supernatants, which suggests that BSF-1 is responsible for this increase in IgE production. Monoclonal antibody to BSF-1 totally inhibits the IgE-enhancing activity of a TH supernatant, lending further support to this conclusion. The effects of BSF-1 on LPS-stimulated B cells are specific for IgE and, as previously reported, IgG1 and IgG3, because the levels of IgM, IgG2a, IgG2b, and IgA in the cultures change relatively little when BSF-1 is added.

Animals↗
PubMed1986

Isolation and characterization of expressible cDNA clones for mouse Thy-1: a model system for cDNA expression of cell surface proteins.

By using the mouse Thy-1 gene as a model, we have developed a procedure to distinguish functional vs nonfunctional cDNA of lymphocyte surface antigens by transfecting COS-7 monkey cells and testing for expression of cell surface products encoded by the cDNA inserts. By cross-hybridization with a mouse Thy-1 probe, we isolated cDNA clones from a pcD-expression library prepared from mRNA of C5 cells. Two functional clones were distinguished from the remainder by detection of Thy-1.2 on the surface of 0.5% of COS-7 cells transiently transfected by the DEAE-Dextran method. Inclusion of chloroquine in the transfection procedure greatly facilitated the detection of functional cDNA by raising the percentage of expressing cells to 30%. Nucleotide sequencing of one functional cDNA, about 1700 bp long, confirmed that the gene encodes a protein whose sequence agrees with the published Thy-1.2 protein sequence with the additional 31 amino acids attached at the COOH-terminus. A 75 bp 5' untranslated region preceding the coding region contains 50 bp not found in the genomic clones. Comparison indicates that one or more introns are present in the 5' untranslated region, but are not found in the mature mRNA. The first exon may be separated by at least 1 kb intron from the initiation codon. Because the expressible clones are approximately the size of the mRNA seen on Northern blots, we believe that these clones are nearly full-length cDNA. Dilution experiments indicate that this strategy should also be useful for identifying functional cDNA clones for cell surface proteins solely on the basis of their expression in mammalian cells.

Animals↗
PubMed1986

Two types of murine helper T cell clone. I. Definition according to profiles of lymphokine activities and secreted proteins.

A panel of antigen-specific mouse helper T cell clones was characterized according to patterns of lymphokine activity production, and two types of T cell were distinguished. Type 1 T helper cells (TH1) produced IL 2, interferon-gamma, GM-CSF, and IL 3 in response to antigen + presenting cells or to Con A, whereas type 2 helper T cells (TH2) produced IL 3, BSF1, and two other activities unique to the TH2 subset, a mast cell growth factor distinct from IL 3 and a T cell growth factor distinct from IL 2. Clones representing each type of T cell were characterized, and the pattern of lymphokine activities was consistent within each set. The secreted proteins induced by Con A were analyzed by biosynthetic labeling and SDS gel electrophoresis, and significant differences were seen between the two groups of T cell line. Both types of T cell grew in response to alternating cycles of antigen stimulation, followed by growth in IL 2-containing medium. Examples of both types of T cell were also specific for or restricted by the I region of the MHC, and the surface marker phenotype of the majority of both types was Ly-1+, Lyt-2-, L3T4+, Both types of helper T cell could provide help for B cells, but the nature of the help differed. TH1 cells were found among examples of T cell clones specific for chicken RBC and mouse alloantigens. TH2 cells were found among clones specific for mouse alloantigens, fowl gamma-globulin, and KLH. The relationship between these two types of T cells and previously described subsets of T helper cells is discussed.

Animals↗
PubMed1986

A T cell activity that enhances polyclonal IgE production and its inhibition by interferon-gamma.

The addition of concanavalin A-stimulated supernatants of the helper T cell clone, D9.1, to cultures of lipopolysaccharide (LPS)-stimulated T-depleted mouse spleen cells caused more than a 100-fold increase in immunoglobulin (Ig) E production. These supernatants cause a 10-fold to 15-fold increase in IgG1, a fivefold to 10-fold increase in IgA, and a fivefold to 10-fold decrease in IgG3. These effects are optimal when the supernatants are added 1 to 2 days after stimulation with LPS. Cells from mouse strains that normally give little or no IgE response in vivo give normal IgE levels in response to LPS plus the supernatant of Concanavalin A-stimulated D9.1 cells in vitro. The enhancement of both IgE and IgG1 can be completely inhibited by relatively low concentrations of interferon-gamma (IFN-gamma). Both the IgE-enhancing activity and IFN-gamma act directly upon purified B cells.

Animals↗
PubMed1986

T-cell and mast cell lines respond to B-cell stimulatory factor 1.

The murine lymphokine B-cell stimulatory factor 1 (BSF-1) has been described previously in terms of its action on B lymphocytes. We now provide evidence that BSF-1 is also responsible for two additional biological activities. The first of these is the stimulation or maintenance of a state of activation in mouse T-cell lines. The second activity is the increase in the proliferative rate of certain mast cell lines costimulated with interleukin 3. The T-cell and mast cell activities are mediated by purified BSF-1 and copurify with BSF-1 from supernatants of certain T-cell lines. Each of these activities is inhibited by monoclonal anti-BSF-1 but not by monoclonal anti-interleukin 2 antibody. The antibody inhibition results also indicate that BSF-1 is the major or only source of these two activities in the activated T-cell supernatants that we have tested.

Animals↗
PubMed1985

cDNA clones encoding IgE-binding factors from a rat-mouse T-cell hybridoma.

cDNA clones encoding rodent IgE-binding factors (IgE-BF) were isolated from cDNA libraries of a rat-mouse T hybridoma that secretes IgE-suppressive factor (IgE-SF) upon incubation with rat IgE. COS7 cells transfected with two of the cDNAs expressed IgE-BF, which selectively potentiate an in vitro IgE response. IgE-BF expressed in COS7 cells are glycoproteins of approximately equal to 60 and approximately equal to 11 kDa. DNA sequence analysis of an IgE-BF cDNA revealed a 556-amino acid (62 kDa) protein coding region. The results suggest that IgE-potentiating and IgE-suppressive factors share common precursor polypeptides and that the 11-kDa IgE-BF is derived from a 60-kDa precursor.

Amino Acid Sequence↗
PubMed1984

A unique series of lymphomas related to the Ly-1+ lineage of B lymphocyte differentiation.

Six new B lineage lymphomas of NFS mice established in primary tissue culture were examined for a number of phenotypic, functional, virologic, and molecular genetic characteristics. Two of the tumors and their cloned derivatives bore surface markers characteristic of B cells, whereas four tumors resembled pre-B cells. One of the B cell and two of the pre-B cell lymphomas had rearrangements of both heavy and light chain immunoglobulin genes, confirming their designation as B-lineage lymphomas. All the tumors but one were Ly-1+, indicating that Ly-1 may be expressed by some pre-B cells as well as some B cells. In addition, one pre-B cell lymphoma was Mac-1+. MCF murine leukemia viruses obtained from two of the tumors did not accelerate development of B-lineage lymphomas in NFS mice.

Animals↗
PubMed1983

Characteristics of thymus-homing bone marrow cells.

Using a short-term in vivo assay, we studied bone marrow cells capable of homing to the thymus of lethally irradiated recipients. In the bone marrow, these cells lack the T cell markers Thy-1 and Lyt. Soon after their homing into the thymus, however, the immigrants begin to express Thy-1 and Lyt antigens, but not TL antigen. Unexpectedly, Lyt antigens appear to be expressed before Thy-1. These thymus-homing bone marrow cells seem to be already separated from the B cell lineage. Most of the homing cells are engaged in the cell cycle.

Animals↗
PubMed1983

Immunoglobulin gene rearrangement during pre-B cell differentiation.

The experiments reported here were designed to answer two questions: (1) At what stage in normal pre-B cell development do immunoglobulin gene rearrangements occur?; and (2) Do heavy chain and kappa light chain genes rearrange in concert, or in an ordered sequence? To answer these questions, we studied immunoglobulin gene rearrangements in pre-B cell populations purified on the fluorescence-activated cell sorter (FACS). Gene rearrangement was assessed by measuring the loss of germ-line joining (J) segment-containing restriction fragments in B cells and two populations of pre-B cells. Large pre-B cells, the earliest identifiable cells in the B lineage, have rearrangements at both JH loci but do not have rearrangements at the kappa chain loci. Thus heavy chain rearrangement occurs concurrently with or prior to the expression of the surface marker B220, which we use to identify and isolate pre-B cells. Small pre-B cells, which include the immediate precursors of B cells, likewise have rearrangements at both JH loci, but may also have J kappa rearrangements. Approximately 1/3 of the J kappa loci are rearranged in small pre-B cells compared to 2/3 in kappa chain-expressing B cells. This suggests that the small pre-B cell population is actively undergoing kappa chain gene rearrangement. The striking asynchrony in heavy and light chain gene rearrangement is reflected at the level of gene expression; both pre-B cell populations synthesize mu chains but not kappa light chains. Heavy chain rearrangement is therefore a very early event in B lineage development and may begin in a cell not yet fully committed to the B lineage, whereas kappa rearrangement occurs just prior to the expression of surface immunoglobulin (sIg) and may be a rate-limiting step in the transition from pre-B to B cells.

Animals↗
PubMed1982

Surface phenotype and migratory capability of Peyer's patch germinal center cells.

Peanut agglutinin (PNA) binds selectively to germinal center cells in mouse peripheral lymphoid organs. Using PNA as a marker, we have determined that Peyer's patch germinal center cells are B cells with a unique phenotype---they express a low level of surface immunoglobulin (about 85% Ig+), predominantly of the IgA class (70% alpha+), with only 10% bearing surface IgM, and few if any expressing IgD. This phenotype identifies murine Peyer's patch germinal center cells as fairly late cells in B cell differentiation, and suggests that they may be precursors of IgA-secreting plasma cells in the gut wall. In addition, we have described a means of purifying PNA+ Peyer's patch lymphocytes, and have demonstrated that these cells lack functional receptors for high endothelial venules and fail to migrate to lymphoid organs in vivo. It is speculated that PNA may be a general marker for nonmigratory lymphocyte populations undergoing local differentiation.

Animals↗
PubMed1982

Surface antigen expression and immunoglobulin gene rearrangement during mouse pre-B cell development.

The first part of this article discusses the isolation and characterization of several monoclonal antibodies to the B lineage-specific surface molecule, B220. B220 was shown to be expressed on precursors of B cells by the demonstration that removal of B220+ cells from B cell-depleted bone marrow removes the ability of bone marrow to regenerate B cells. Although these antibodies recognize a broad range of differentiation stages within the B lineage, they can be used to isolate highly enriched populations of pre-B cells from mouse bone marrow. We also describe the use of antibodies to the surface markers B220 and ThB to define two sequential stages of pre-B cell differentiation. A simplified diagram of our current view of the B lineage differentiation sequence is shown in Figure 4. No attempt has been made to include the various functionally defined B cell subsets on this diagram since we know almost nothing about the expression of these two surface markers on them. This model reflects an assumption that the early part of B cell differentiation is a linear rather than a branching pathway. At present, there is no evidence for a branching pathway, but little evidence against it either. B220 is the first B cell-specific molecule known to be expressed during differentiation and it continues to be expressed on most subsequent B lineage cells. In this regard, it resembles the Thy-1 molecule on thymus-derived lymphocytes and, like Thy-1, B220 should be quite useful for identifying and classifying B lineage cells. One example of this is the use of B220 expression to clearly assign germinal center cells to the B lineage. The example of Thy-1+, RA3-2C2+ cells from mice with the lpr/lpr genotype, however, suggests that some caution should be used when interpreting data, especially with pathological samples. The availability of substantially purified pre-B cell populations has made it possible to follow changes in immunoglobulin gene organization and expression during differentiation. Our current understanding of these events is also shown in Figure 4, correlated with cell surface phenotype. The large pre-B cell population has extensive heavy chain rearrangements and synthesizes significant quantities of mu heavy chain, but does not yet have detectable light chain gene rearrangement. The small pre-B population consists of two cell types, some with kappa gene rearrangement and some without. This suggests that kappa rearrangement occurs within this cell population, which is homogeneous with respect to morphology and surface phenotype. The asynchrony of heavy and light chain gene rearrangement results in an asynchrony at the level of expression of these genes as well, but the purpose of this remains one of many unanswered questions about pre-B cell differentiation. Now that it is possible to identify, isolate, and manipulate pre-B cells as readily as B or T cells, many of these questions may now be addressed.

Animals↗
PubMed1982

High molecular weight lymphocyte surface proteins are structurally related and are expressed on different cell populations at different times during lymphocyte maturation and differentiation.

HMW lymphocyte surface proteins T20 and B220, which are expressed on T and B cells, respectively, have been found to be extensively related in structure, beyond what would be expected by the sharing of the determinant detected by monoclonal antibody 13/2. In addition, another HMW protein (T200A) has been discovered, which is preferentially expression proliferating T cells, and which exhibits significant structural homology with T200, but does not express the 13/2 determinant. T200A bears a novel antigenic determinant, detected by monoclonal antibody BS-S28E, which is not shared by either T200 or B220. A fourth HMW protein (170/100) has been found, which is expressed on most lymphocytes, but which is neither structurally nor antigenically related to T200A, T200, or B220. Monoclonal antibodies reactive with 170/100 inhibit T cell-mediated cytolysis, although monoclonal antibodies reactive with T200A, T200, or B220 do not.

Animals↗
PubMed1982

Abnormalities induced by the mutant gene Ipr: expansion of a unique lymphocyte subset.

Mice carrying the Ipr mutation develop massive lymphoadenopathy and severe autoimmune disease. The characteristics of the cell population that proliferates in lymphoid tissues were evaluated by the use of a) monoclonal antibodies and FMF, and b) molecular genetic studies of Ig heavy chain genes. The lymph node cells of different strains of mice homozygous for the Ipr mutation were shown to be almost uniformly Thy-1+, Ly-1+, Ly-2-, H-11+, Ly-5+, sIg-, ThB-, 2C2+, I-A-, 6B2+, and therefore to have surface characteristics of both T and B cells. Molecular genetic studies of the arrangements of Ig heavy chain genes showed that they were not rearranged as in pre-B and B cells. These results suggest that an abnormal proliferating population of T cells in Ipr/Ipr mice aberrantly express B cell surface markers.

Animals↗
PubMed1982

Surface phenotype of Peyer's patch germinal center cells: implications for the role of germinal centers in B cell differentiation.

The surface phenotype of Peyer's patch germinal center lymphoid cells in the mouse is described. It is confirmed that most germinal center lymphocytes bind high levels of peanut agglutination (PNA), a lectin with specificity for terminal galactosyl residues. It is shown that germinal center lymphocytes can be identified in cell suspensions as a discrete PNAhi population distinct from other B cells, plasma cells, and most T cells, which bind only low levels of PNA. Using fluorescence-labeled PNA as a marker in dual fluorescence studies, we found that the majority of Peyer's patch germinal center cells are B lymphocytes: PNAhi Peyer's patch cells express B220, the B lineage-specific form of the T200 family of molecules, as well as low levels of surface Ig. They do not express the T cell-lineage antigens Thy-1, Lyt-1, or Lyt-2 (only 1 to 3% positive). They bear lower levels of H2-K than PNAlo B cells, but two to three times the level of surface I-A-encoded determinants. A discrete but variable subpopulation of PNAhi Peyer's patch cells bear ThB in AKR/c mice, but BALB/c PNAhi lymphocytes are ThB-. About 10 to 30% bear surface IgM or IgG, but in contrast to essentially all PNAlo B lymphocytes in this site, they express no detectable surface IgD. The majority of Peyer's patch germinal center cells bear surface IgA, and this IgA is allelically excluded in F1 mice, indicating it is synthesized by the germinal center cells themselves. In fact, germinal centers contain most of the IgA-bearing cells in Peyer's patches (70 to 85%). These findings lend considerable support to the concept that germinal centers in Peyer's patches are the site of generation of precursors of the IgA-secreting plasma cells that characterize mucosal immune responses, and also suggest that germinal centers may play an important role in the process of heavy chain class switching.

Alleles↗