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Biomedical subjects

H Band

Publications and source records attributed to H Band.

72 records · Page 4Linked to original sources
PubMed1989

Antiproliferative effect of gossypol and its optical isomers on human reproductive cancer cell lines.

The antiproliferative effect of gossypol and its optical isomers on various human cell lines of reproductive and nonreproductive tissue origin was studied. Various reproductive cancer cell lines of ovarian, gestational, and testicular origin were highly sensitive (IC50 values of 0.86-1.98) to gossypol. The antiproliferative action of gossypol was not restricted to reproductive cancers, as non-reproductive cancer cell lines were also equally sensitive (IC50 values of 0.69-3.55). In addition, actively proliferating untransformed cells such as fibroblasts and PHA-activated lymphocytes were also sensitive (IC50 values of 0.87-2.51). (-)-Gossypol was 3.6-12.4 times more potent than (+)-gossypol and 1.48-2.65 times more potent than (+/-)-gossypol. The most sensitive indicator of gossypol action was a decrease in DNA synthesis followed by inhibition of protein synthesis and uptake of rhodamine-123 by mitochondria as tested in an ovarian cancer cell line (OVCA 433) and a fibroblast line (Hs27). These results indicate that gossypol possesses a general nonselective antiproliferative action toward human cells in vitro. Further, the pharmacologic activity of gossypol as an antiproliferative agent is primarily attributable to its (-) isomer, which is also the active isomer as a contraceptive.

Antineoplastic Agents↗
PubMed1989

Differential expression of MHC class II antigens in myelomonocytic leukemia cell lines.

Major histocompatibility complex (MHC) class II antigens are discordantly expressed on hematopoietic progenitor cells. Their expression is linked to differential responsiveness of the cells to growth factors and inhibitors. We examined the expression of different MHC class II antigens in a panel of human myelomonocytic cell lines representing different stages of differentiation, by cytofluorographic analysis with monoclonal antibody (MoAb) and Northern blot analysis with specific cDNA probes. These analyses revealed discordant expression of different MHC class II antigens both in basal state and after gamma-IFN induction. Thus KG-1 myeloblast cells express all class II antigens (DR greater than DP greater than DQ) constitutively and their expression increased after gamma-IFN treatment. KG-1a, an immature blast variant of KG-1, does not express class II antigens, even after gamma-IFN treatment. THP-1, a monocytic cell line expresses DR but not DP or DQ under basal conditions. DP and DQ are, however, gamma-IFN inducible. The class II negative HL-60 promyelocytic cell line, expresses DR and DP but not DQ after gamma-IFN induction. In all the above cell lines, surface expression of class II antigens correlated with the levels of mRNA expression as determined with specific cDNA probes. In U-937, a monocytic cell line, no surface expression of class II MHC antigens was observed either with or without gamma-IFN, however, specific mRNA message was observed under basal conditions and was further increased with gamma-IFN, indicating a possible defect in assembly or transport of class II antigens. The patterns of class II MHC antigens in these leukemic cell lines may be a useful model to delineate molecular basis of discordant MHC class II expression during myelomonocytic differentiation.

Animals↗
PubMed1988

Characterization of a third form of the human T cell receptor gamma/delta.

A subpopulation of the CD3+ peripheral T lymphocytes express the TCR-gamma/delta complex. Three distinct TCR-gamma forms that differ in size and in the ability to form a disulfide bridge with the TCR-delta subunit have been described. In this study we analyze the structural difference between the non-disulfide-linked 55-kD and 40-kD TCR-gamma chains. The 40-kD TCR-gamma form contains a smaller polypeptide backbone and carries less carbohydrate compared with the 55-kD TCR-gamma form. A cDNA clone corresponding to the 40-kD TCR-gamma subunit lacks one copy of the second exon of the constant region that is present in the other TCR-gamma subunit. This exon copy encodes part of the connector region that is located between the constant domain and the membrane spanning region. We show that the number of potential N-linked glycan attachment sites are the same for the two TCR-gamma forms. Since these attachment sites are located in the connector region we conclude that the connector region influences the amount of N-linked carbohydrates added to the core TCR-gamma polypeptide, probably by affecting the conformation of the protein. In contrast to the TCR-beta constant region usage, the TCR-gamma constant regions are unequally expressed. Virtually exclusive usage of disulfide-linked complexes were found in some individuals, while both the disulfide-linked and the 40-kD, non-disulfide-linked TCR-gamma forms were detected in other subjects. The ability to distinguish these TCR-gamma/delta forms now makes it possible to study the mechanisms that govern their selection and to determine if they correspond to functionally distinct isotypes.

Amino Acid Sequence↗
PubMed1988

Extensive junctional diversity of rearranged human T cell receptor delta genes.

The human T cell receptor delta (TCR delta) gene encodes one component of the TCR gamma delta-CD3 complex found on subsets of peripheral blood and thymic T cells. Human TCR delta diversity was estimated by characterizing rearrangements in TCR gamma delta cell lines and determining the structures of complementary DNA clones representing functional and nonfunctional transcripts in these cell lines. One V delta segment and one J delta segment were identified in all functional transcripts, although a distinct J delta segment was identified in a truncated transcript. Further, one D delta element was identified, and evidence for the use of an additional D delta element was obtained. Thus human TCR delta genes appear to use a limited number of germline elements. However, the apparent use of two D delta elements in tandem coupled with imprecise joining and extensive incorporation of N nucleotides generates unprecedented variability in the junctional region.

Amino Acid Sequence↗
PubMed1987

Immunochemical proof that a novel rearranging gene encodes the T cell receptor delta subunit.

The T cell receptor (TCR) delta protein is expressed as part of a heterodimer with TCR gamma, in association with the CD3 polypeptides on a subset of functional peripheral blood T lymphocytes, thymocytes, and certain leukemic T cell lines. A monoclonal antibody directed against TCR delta was produced that binds specifically to the surface of several TCR gamma delta cell lines and immunoprecipitates the TCR gamma delta as a heterodimer from Triton X-100 detergent lysates and also immunoprecipitates the TCR delta subunit alone after chain separation. A candidate human TCR delta complementary DNA clone (IDP2 O-240/38), reported in a companion paper, was isolated by the subtractive library approach from a TCR gamma delta cell line. This complementary DNA clone was used to direct the synthesis of a polypeptide that is specifically recognized by the monoclonal antibody to TCR delta. This complementary DNA clone thus corresponds to the gene that encodes the TCR delta subunit.

Antibodies, Monoclonal↗
PubMed1987

Structurally divergent human T cell receptor gamma proteins encoded by distinct C gamma genes.

The human T cell receptor (TCR) gamma polypeptide occurs in structurally distinct forms on certain peripheral blood T lymphocytes. Complementary DNA clones representing the transcripts of functionally rearranged TCR gamma genes in these cells have been analyzed. The expression of a disulfide-linked and a nondisulfide-linked form of TCR gamma correlates with the use of the C gamma 1 and C gamma 2 constant-region gene segments, respectively. Variability in TCR gamma polypeptide size and disulfide linkage is determined by the number of copies and the sequence of a repeated segment of the constant region. Thus C gamma 1 and C gamma 2 are used to generate structurally distinct, yet functional, T3-associated receptor complexes on peripheral blood lymphocytes. Tryptic peptide mapping suggests that the T3-associated TCR gamma and delta peptides in the nondisulfide-linked form are distinct.

Amino Acid Sequence↗
PubMed1987

Inhibition of the interaction of mycobacteria with Schwann cells by antimycobacterial antibodies.

The effect of antimycobacterial serum on the uptake of Mycobacterium w by 33B rat Schwannoma cell line and rat peritoneal macrophages was studied. Incubation of Mycobacterium w with antimycobacterial serum caused a marked inhibition of its uptake by 33B cells but did not diminish its uptake by macrophages. These results suggest that the mechanism of the interaction of mycobacteria with Schwann cells differs from that with macrophages.

Animals↗
PubMed1987

Southern blot analysis of BII cell line--a putative variant of HL-60.

Southern blot analysis of various genes was used to compare the human promyelocytic leukemia cell line HL-60 and the BII cell line, which reportedly arose as a spontaneous differentiation inducer-resistant variant from an HL-60 culture. Granulocyte-macrophage colony stimulating factor gene restriction fragment polymorphism, due to a partial deletion of one of the alleles of this gene in HL-60, was not observed in the BII cells. Furthermore, the p53 oncogene, most of which is deleted in the HL-60 cell line, was found to be intact in the BII cell line. Human leukocyte antigen typing revealed that the two cell lines shared the A locus but differed at the B locus. Several unique restriction fragments hybridizing to human leukocyte antigen class I and DR beta gene probes were observed in the DNA digests of each cell line. Altogether these data provide definitive evidence that BII represents a human cell line of different origin than HL-60. Further lineage determination of this cell line could add a useful member to the group of leukemic cell lines.

Antigens, Neoplasm↗
PubMed1986

Mechanism of phagocytosis by Schwann cells.

33B rat Schwannoma cell line is known to exhibit phagocytic properties analogous to those of normal Schwann cells. The mechanism of phagocytosis by this cell line was investigated by studying the effect of known modulators of phagocytosis on the uptake of latex particles by these cells. Treatments which block energy production of the host cell, such as incubation at 4 degrees C and treatment with sodium azide, markedly inhibited the phagocytosis of latex particles by these cells. Phagocytosis was dose-dependently, and completely, inhibited by cytochalasin B, demonstrating an important role of microfilaments. Colchicine produced a minor inhibition of phagocytosis only at the highest concentration (10(-3) M) tested, suggesting that intact microtubules are not crucial for latex phagocytosis. Dibutyryl cyclic AMP was without any effect on the phagocytosis. Thus, latex phagocytosis by rat Schwannoma cells is an active, energy-dependent process requiring intact microfilaments with only a minor dependence on microtubules.

Animals↗
PubMed1986

Effect of macrophage activators on the phagocytosis of mycobacteria by Schwann cells.

Concanavalin A-induced lymphokines decreased the phagocytosis of 14C-acetate-labelled Mycobacterium w by 33B rat Schwannoma cells while increasing the phagocytosis by macrophages. This suggests that Schwann cells are responsive to lymphokines. Phorbol myristate acetate decreased the phagocytosis in Schwannoma cells but increased that in macrophages. Schwann cells, thus, respond to stimulants of macrophage phagocytosis in a manner opposite to that of macrophages.

Animals↗
PubMed1986

Interleukin 1--a possible mediator of neural fibrosis in leprosy.

Neural fibrosis in leprosy, the disease caused by the obligate intracellular bacterium, Mycobacterium leprae, is closely related to the cell-mediated immune response to this microorganism. The fibrosis appears to be due to soluble mediators released by the immune effector cells. Interleukin 1, a macrophage product that stimulates fibroblast migration, proliferation and synthetic activity, possesses the requisite properties to qualify for such a mediator.

Humans↗