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P Stashenko

Publications and source records attributed to P Stashenko.

72 records · Page 4Linked to original sources
PubMed1987

Interleukin-1 beta is a potent inhibitor of bone formation in vitro.

The effect of interleukin-1 beta, the major component of osteoclast-activating factor (OAF), on bone formation by fetal rat osteoblast-rich cells was investigated. An in vitro culture system developed by Ecarot-Charrier et al. (1983) and Bellows et al. (1986) was utilized in which osteoblasts form mineralized nodules which closely resemble woven bone. Continuous exposure of cultures to homogenous IL-1 beta resulted in potent inhibition of mineralized nodule formation, which was half maximal at 0.1 U/ml (7.5 X 10(-13) M). Bone formation may thus be considerably more sensitive to IL-1 beta than is bone resorption (half maximal at 3.8 X 10(-11) M). Inhibition of bone formation occurred when cultures were exposed to IL-1 beta at both early and late time periods and was unaffected by the presence of indomethacin or by the osteoclast inhibitors calcitonin and gamma-interferon. Instead, IL-1 beta exerted multiple inhibitory effects on osteoblast functions, including inhibition of collagen and noncollagen protein synthesis, alkaline phosphatase expression, and cell replication. On a dose response basis, the inhibition of protein synthesis correlated most closely with inhibition of bone formation. IL-1 beta is clearly inhibitory rather than stimulatory for bone formation as assessed in this system and is therefore unlikely to function as a coupling factor linking the processes of bone resorption and bone formation.

Animals↗
PubMed1986

Effect of monoclonal antibodies against lipoteichoic acid from the oral bacterium Streptococcus mutans on its adhesion and plaque-accumulation in vitro.

Five monoclonal antibodies directed against Streptococcus mutans strain JBP lipoteichoic acid (LTA) were characterized. They were all similarly reactive with the immunizing LTA-containing extract, with intact Strep. mutans JBP cells and with LTA purified from Lactobacillus casei. Immobilized anti-LTA antibodies removes LTA from LTA-containing extracts. The binding of antibodies to LTA was inhibited by the aqueous extract but not by the organic extract of de-acylated LTA, indicating reactivity with the polyglycerol-phosphate portion of the molecule. Antibodies were reactive with all serotypes of Strep. mutans, as well as with strains of Streptococcus salivarius, Streptococcus sanguis and L. casei, but not with LTA-negative species Streptococcus mitis or Actinomyces viscosus. Anti-LTA antibodies at doses of 0.3 or 3.0 micrograms/ml, had no effect on the adherence of Strep. mutans JBP to experimental salivary pellicles formed on hydroxyapatite, but enhanced adherence 150-300 per cent at 30 micrograms/ml. There was no effect of anti-LTA antibodies in a chemostat model which measured sucrose-dependent plaque accumulation by Strep. mutans. The results argue against a major role for LTA in Strep. mutans adherence or plaque accumulation in vitro.

Adhesiveness↗
PubMed1982

Regulatory effect of monocytes on T cell proliferative responses to oral microbial antigens.

Mononuclear cell preparations isolated by Ficoll-Hypaque centrifugation from human peripheral blood were found to vary considerably in the number of monocytes they contained (mean, 20.3%; range, 13 to 33%). The regulatory role of monocytes in T cell proliferative responses to sonic extracts of a panel of oral microorganisms was therefore investigated. T cells were fractionated by anti-immunoglobulin chromatography and depleted of monocytes by treatment with a monoclonal anti-human Ia-like (DR locus antigen) antibody and complement. Purified populations of monocytes were obtained by extensive adherence procedures. The resultant cell populations were greater than 95% pure, as judged by indirect immunofluorescence on a fluorescence-activated cell sorter. Monocyte-depleted T cells failed to respond by proliferation to the nonoral antigen tetanus toxoid, as well as to any oral microorganism, but retained responsiveness to phytohemagglutinin. Readdition of monocytes in final concentrations of from 5 to 15% resulted in the restoration of maximal T cell proliferation. Monocytes in greater numbers suppressed T cell responses to all sonic extracts tested.

Actinobacillus↗
PubMed1981

Stages of B cell differentiation in human lymphoid tissue.

Monoclonal antibodies reactive with B cell-specific differentiation and other antigens were used to investigate stages of B cell maturation in human lymphoid tissue, using an immunoperoxidase technique on frozen tissue sections. Lymphoid follicles, which represent the major anatomic compartment of B cells, demonstrated cellular antigenic expressions that appear to reflect differentiation of B cells. The majority of cells in the primary follicles and the mantle zones of secondary follicles expressed surface antigens similar to those of circulating B cells, namely IgM, IgD, Ia, B1, and B2. In contrast, the germinal center cells of secondary follicles stained for IgM, IgG, B1, B2, and Ia antigens, but not for IgD, and furthermore, acquired the T10 antigen. The germinal centers stained much more intensely than mantle zones with anti-B2, whereas no such striking difference in the staining intensity was observed with anti B1. Plasma cells, which represent the end stage of B cell differentiation, showed intense cytoplasmic staining with the anti-T10 antibody. The results indicate that the generation of germinal center cells in primary lymphoid follicles involves phenotype changes that correspond largely to those previously observed after both antigenic and mitogenic activation of B lymphocytes.

Antigens, Surface↗
PubMed1981

Monoclonal antibody identifies a new Ia-like (p29,34) polymorphic system linked to the HLA-D/DR region.

The Ia antigens of the mouse are the basis for the genetic control of the immune response. The HLA-D/DR locus is considered to be the human counterpart of the Ia subregion of the murine major histocompatibility complex. The HLA-D/DR antigens are polymorphic, and eight well defined alleles have been identified using alloantisera. More recently, 'supertypic' antigens (MB and MT) have been defined which identify clusters of HLA-D/DR specificities. Little is known about the molecular basis for the cellular and serological polymorphism of the HLA-D/DR antigens, as alloantisera are usually of very low titre and heteroantisera frequently lack monospecificity. We present here the preparation and characterization of a monoclonal antibody which defines a new polymorphic system of the HLA-D/DR region. This and similar antisera should now begin to provide the reagents with which to correlate molecular structure with the functional repertoire of the human Ia-like antigens.

Antibodies↗
PubMed1981

Monoclonal antibodies defining serologically distinct HLA-D/DR related Ia-like antigens in man.

Four monoclonal antisera-identifying antigens with the identical tissue distribution and molecular weight of previously described Ia-like antigens were characterized. Two of these antisera, I-1 and I-2, identified antigens expressed on the HLA-D/DR positive cells from all HLA heterozygous individuals. Further characterization on homozygous typing cells (HTC's) demonstrated that I-2 was not reactive with most Dw7 and Dw11 HTC's. Monoclonal antisera, termed I-LR1 and I-LR2, defined polymorphic Ia-like antigens that demonstrated restricted expression on cells from HLA heterozygous individuals. Antigen I-LR1 was expressed on cells from 60% of HLA heterozygotes and its reactivity with HTC's did not conform to any previously described monotypic or supertypic HLA-D/DR pattern. In contrast, I-LR2 was expressed on 40% of HLA heterozygotes and identified only HLA-DR3, 5 and 6 HTC's. Studies of families with HLA recombinants permitted the demonstration that the I-LR1 and I-LR2 antigens are tightly linked to the HLA-D/DR locus. These experiments permit the direct demonstration by immunoprecipitation, linkage studies, and MHC recombinant families that the p29,34 complex in man is closely linked to or is within the HLA-D/DR locus. These studies suggest that the human Ia-like antigens are more heterogeneous than previously demonstrated and that monoclonal antisera will be useful in further defining the structural, genetic, and functional characteristics of these molecules.

Animals↗
PubMed1981

Human cell lines express multiple populations of Ia-like molecules.

Three monoclonal antibodies have been used to isolate Ia-like antigens from three human cell lines; two of which are thought to be homozygous at the HLA-D/DR locus. Complete extraction of the Ia antigens identified by one antibody leaves those recognized by the two remaining antibodies in three parallel sets of experiments, indicating that the antigenic determinants recognized by these antibodies are present on three different populations of Ia molecules from cells of single individuals. These three populations of Ia-like molecules may reflect serologic variants of the product of a single genetic locus or may represent the products of as many as three nonallelic genetic regions. Demonstration of the existence of these multiple populations of Ia-like molecules on presumed homozygous typing cells indicates that this antigenic system is much more complex than has been generally realized. Further study may clarify the relationship between HLA-D/DR type and susceptibility to a variety of diseases and ultimately lead to better matches and improved survival for allogenic transplants. Since the HLA-D region is intimately involved in regulation of the immune response and susceptibility to a variety of diseases, use of monoclonal antibodies specific for discrete Ia antigens, the only identified products of the HLA-D region, may facilitate dissection of its many biological functions.

Antibodies, Monoclonal↗
PubMed1981

Expression of cell surface markers after human B lymphocyte activation.

The fate of two recently described human B lymphocyte-specific antigens (B1 and B2) was studied after B-cell activation in vivo and in vitro. Whereas both B1 and B2 were present on virtually all B cells from normal lymph nodes, B2 was absent from approximately 50% of B cells from hyperplastic lymph nodes. When B cells from spleen, tonsil, or peripheral blood were stimulated in vitro with pokeweed mitogen, activated cells were found to lose B2 (days 4-5) and subsequently B1 (days 6-7). Temporally, B2 loss was accompanied by loss of surface IgD, expression of T10, and the development of intracytoplasmic IgM; B1 loss was correlated with the acquisition of surface IgG and the appearance of intracytoplasmic IgG. Peripheral blood B cells, on which B2 is normally only weakly expressed (B1++++B2+) in contrast to B cells from secondary lymphoid organs (B1++++B2++), exhibited a transitory increase in B2 expression to the B1++++B2++ phenotype prior to B2 disappearance during activation. Taken together with other findings, this observation suggests that peripheral blood may contain a relatively immature subpopulation of B cells.

Antibody-Producing Cells↗
PubMed1981

A unique cell surface antigen identifying lymphoid malignancies of B cell origin.

A monoclonal antibody (anti-B1) specific for a unique B cell surface differentiation antigen was used to characterize the malignant cells from patients with leukemias or lymphomas. All tumor cells from patients with lymphomas or chronic lymphocytic leukemias, bearing either monoclonal kappa lambda light chain, expressed the B1 antigen. In contrast, tumor cells from T cell leukemias and lymphomas or acute myeloblastic leukemia were unreactive. Approximately 50% of acute lymphoblastic leukemias (ALL) of non-T origin and 50% of chronic myelocytic leukemia in blast crisis were also anti-B1 reactive. moreover, 21 of 28 patients with the common ALL antigen (CALLA) positive form of ALL were anti-B1 positive, whereas 0 of 13 patients with CALLA negative ALL were reactive. These observations demonstrate that an antigen present on normal B cells is expressed on the vast majority of B cell lymphomas and on approximately 75% of CALLA positive ALL, suggesting that these tumors may share a common B cell lineage.

Antibodies↗
PubMed1981

Characterization of a human B cell-specific antigen (B2) distinct from B1.

A human B lymphocyte-specific antigen (B2) was identified and characterized by the use of a monoclonal antibody. By indirect immunofluorescence and quantitative absorption, B2 was shown to be expressed exclusively on Ig+ B cells isolated from peripheral blood and lymphoid tissues. In contrast, B2 was not found on monocytes, resting and activated T cells, Null cells, or granulocytes, nor was it found on cell lines or tumor cells of T cell or myeloid origin. Functional studies demonstrated that only B2 antigen-positive splenocytes could be induced to differentiate into plasma cells under the stimulus of pokeweed mitogen, further confirming the B cell specificity of B2. It was then demonstrated that the B2 antigen was distinct from the previously described B cell-surface determinants including surface immunoglobulin, Ia-like antigens, and Fc and C3 receptors. More importantly, the B2 antigen has been clearly shown to be distinct from the previously described B cell-specific antigen, B1, by its m.w. and expression on normal and malignant B lymphocytes. The distinct distribution of B2 on normal and malignant lymphocytes supports the notion of B cell heterogeneity and provides further evidence for existence of subpopulations of human B lymphocytes.

Absorption↗
PubMed1980

A monoclonal antibody defining a lymphoma-associated antigen in man.

A monoclonal antibody (Ab 89) was developed against a lymphoma-associated antigen on the tumor cells of a patient (N.B.) with a B cell, poorly differentiated lymphocytic lymphoma (D-PDL). By indirect immunofluorescence, Ab 89 was shown to react only with N.B. lymphoma cells and was unreactive with normal N.B. lymphoid cells, normal fractionated peripheral blood cells, other normal lymphoid tissues, fetal tissues, and non-lymphoid malignant cells. In addition, Ab 89 was unreactive with conventional immunoglobulins, private and public HLA antigens, or Ia-like antigens. More importantly, Ab 89 was reactive with some B cell lymphoid malignancies. Of the 57 B cell lymphomas tested, it was found that Ab 89 reacted with approximately 10% of B cell D-PDL and B cell chronic lymphocytic leukemia (CLL). Of interest was the finding that N.B. serum contained a circulating antigen which could specifically block the reactivity of Ab 89. The data obtained suggests that Ab 89 defines a tumor-associated antigen shared by a unique subgroup of B cell lymphomas. The group of patients reactive with Ab 89 did not fall into any histopathologic classification system. These data support the notion that there is greater heterogeneity of B cell lymphomas than may have been previously recognized.

Absorption↗
PubMed1980

Characterization of a human B lymphocyte-specific antigen.

A human B lymphocyte-specific antigen (B1) was identified and characterized by the use of a monoclonal antibody. By indirect immunofluorescence, cytotoxicity, and quantitative absorption, B1 was present on approximately 9% of the peripheral blood mononuclear cell fraction and >95% of B cells from blood and lymphoid organs in all individuals tested. Monocytes, resting and activated T cells, null cells, and tumors of T cell and myeloid origin were B1 negative. B1 was distinct from standard B cell phenotypic markers, including Ig and Ia antigen. Removal of the B1 positive population in peripheral blood eliminated all B cells capable or responding to pokeweed mitogen by maturation to Ig-producing cells.

Absorption↗
PubMed1980

Analysis of the primary anti-(4-hydroxy-3-nitrophenyl) acetyl (NP) responsive B cells in BALB/C and B10.D2 mice.

The chain composition and fine specificity of the anti-(4-hydroxy-3-nitrophenyl) acetyl (NP) response was examined at the level of individual clones in BALB/c (Ig-1a allotype) and B10.D2 (Ig-1b) mice. The primary anti-NP serum response of B10.D2 is distinguished from that of BALB/c by its restricted heterogeneity and unusual heteroclitic fine specificity, which appear to be associated with antibodies bearing a unique allotype-linked idiotype(s) (NP-b) paired with lambda light (L) chains. At the clonal precursor level, the 10.d2 anti-NP primary response was found to be characterized by less diversity than that of BALB/c and is dominated by several clonotypes with the heteroclitic fine specificity. However, BALB/c also possess abundant heteroclitic precursors (53%), which are expressed but apparently obscured in its more heterogeneous serum response. Heteroclitic fine specificity in both strains is occasionally associated with clones bearing kappa as well as lambda L chains.

Animals↗
PubMed1980

Serotherapy of a patient with a monoclonal antibody directed against a human lymphoma-associated antigen.

A preliminary serotherapeutic trial was undertaken with a monoclonal antibody designated antibody 89 (Ab 89) directed against a lymphoma-associated antigen. In vitro studies demonstrated that Ab 89 could mediate complement-dependent lysis and macrophage adherence but not antibody-dependent cell-mediated cytotoxicity. To evaluate toxicity and therapeutic efficacy, two courses of Ab 89 were administered to a patient with an Ab 89-reactive tumor. Transient decreases in the number of circulating tumor cells and the appearance of circulating dead cells were noted with the infusion of Ab 89. Following administration of 150 mg or more of Ab 89, small amounts of antibody could be demonstrated on circulating tumor cells at a time when no free antibody was found in the serum. The inability to deliver a significant amount of Ab 89 to tumor cells in vivo is thought to be secondary to a circulating tumor antigen. Following each infusion, the amount of this blocking antigen decreased but could not be entirely cleared from the serum. This study provides preliminary evidence for the lack of clinical toxicity of a monoclonal antibody and identifies circulating blocking antigens as a significant obstacle to serotherapy.

Antibodies, Neoplasm↗
PubMedDate not supplied

Effect of immune cytokines on bone.

The effect of the bone resorptive cytokines IL-1 alpha, IL-1 beta, and TNF on bone formation was studied in an in vitro system. All three cytokines were profoundly inhibitory, with the rank order of potency IL-1 beta greater than IL-1 alpha greater than TNF. Inhibition was mediated by a depression of differentiated osteoblast functions, including alkaline phosphatase expression and matrix synthesis. Osteoblast proliferation was not affected. Bone formation inhibition was independent of PGE2 production, indicating a direct effect of cytokines on osteoblasts. High concentrations of IL-1 beta (10 U/ml) abrogated IGF-1-stimulated bone formation, providing evidence for the hypothesis that cytokines act as 'uncoupling factors'. Conversely, high concentrations of IGF-1 circumvented inhibition by IL-1 beta (0.1-1.0 U/ml). The interaction of cytokines and bone growth factors with osteoblasts are likely to be of critical importance in the regulation of bone mass at local inflammatory sites.

Animals↗