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R F Todd

Publications and source records attributed to R F Todd.

At least 127 records · Page 7Linked to original sources
PubMed1987

Deficiency of leukocyte surface glycoproteins Mo1, LFA-1, and Leu M5 in a dog with recurrent bacterial infections: an animal model.

A dog with severe recurrent bacterial infections, impaired pus formation, delayed wound healing, and severe persistent leukocytosis was the result of a mother-son mating. Assessment of leukocyte function revealed profound abnormalities in adherence-dependent activities including impaired granulocyte adhesion to glass/plastic surfaces or nylon wool, decreased granulocyte aggregation and chemotaxis, and diminished lymphocyte blastogenesis, but normal neutrophil oxidative activity, serum immunoglobulin, and complement levels. By immunofluorescence analysis, CD11b and CD18 monoclonal antibodies specific for the 155-kd alpha polypeptide of Mo1 (gp 155, 94) and the 94 kd beta peptide common to Mo1, LFA-1 (gp 170, 94), and Leu M5 (p 150, 94) (surface molecules that promote leukocyte adhesion) failed to bind to unstimulated and A23187 calcium ionophore-stimulated granulocytes or mononuclear cells of the affected dog as compared with strong specific binding to canine control cells. The Mo1 glycoproteins were only barely detectable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of immunoprecipitates from lysates of 125I surface-labeled neutrophils from the affected dog as compared with intense bands seen with canine control cell precipitates. We conclude that this dog has a severe leukocyte surface glycoprotein deficiency syndrome that is similar, if not identical, to that recently recognized in humans. Dogs with deficiency of leukocyte Mo1, LFA-1, and Leu M5 expression may represent a useful animal model to characterize further the molecular basis for an inherited disorder in leukocyte effector function.

Animals↗
PubMed1986

N-terminal sequence of human leukocyte glycoprotein Mo1: conservation across species and homology to platelet IIb/IIIa.

Mo1 and gp160-gp93 are two surface membrane glycoprotein heterodimers present on granulocytes and monocytes derived from humans and guinea pigs, respectively. We purified both antigens and found that their alpha subunits had identical N-termini which were significantly homologous to the alpha subunit of the human adhesion platelet glycoprotein IIb/IIIa.

Amino Acid Sequence↗
PubMed1986

Two functional domains in the phagocyte membrane glycoprotein Mo1 identified with monoclonal antibodies.

Granulocytes from patients genetically deficient in the leukocyte glycoprotein family, Mo1, LFA-1, and Leu-M5 (P150,94), have defective complement receptor type III (CR3) activity as well as abnormal adhesion-dependent functions such as spreading, chemotaxis, and phagocytosis. To determine the contribution of the Mo1 heterodimer deficiency to the various functional aberrations observed in deficient granulocytes, we mapped the functional domains of Mo1 using several monoclonal antibodies to this molecule. In addition to iC3b binding, two granulocyte adhesion functions were examined: Cell spreading on plastic coverslips and chemotaxis. One monoclonal antibody to Mo1, 44, inhibits all three functions. Other monoclonal antibodies (903, Leu-15, and OKM10) inhibit iC3b binding to granulocytes but have no effect on cell spreading and/or chemotaxis. Another antibody, 904, has no significant inhibition of iC3b binding but inhibits spreading on plastic and chemotaxis. These studies suggest the presence of two functional domains in Mo1: one involved in iC3b binding and the other in enhancing certain granulocyte adhesion-dependent functions.

Antibodies, Monoclonal↗
PubMed1986

A monoclonal antibody specific for a monocyte-macrophage membrane component blocks the human monocyte response to migration inhibitory factor.

In our study of the human monocyte response to migration inhibitory factor (MIF), we screened murine anti-monocyte monoclonal antibodies (MAb) for their ability to affect the MIF response. When blood monocytes were preincubated for 30 min at 37 degrees C with MAb of various cell specificities, it was found that Mo3e-MAb could inhibit the monocyte response to MIF. This effect was observed at an antibody concentration of 0.37 microgram/10(6) monocytes. This blocking activity appeared to be specific for Mo3e-MAb, since MAb specific for Mo1, Mo2, Mo4, alveolar macrophage (PAM-1), and platelet (Plt-1) antigens were unable to block the MIF response. Specificity was also shown by experiments performed with MAb similar to Mo3e-MAb in their immunofluorescence staining patterns. Two MAb of this type were not able to block the MIF response. All of these MAb are of the IgM isotype, and therefore it is unlikely that the blocking activity of Mo3e-MAb is mediated by the Fc receptor. These studies suggest that Mo3e-MAb may represent an anti-MIF receptor antibody. Mo3e-MAb recognizes a protease-sensitive antigen of 80 kD and 50 kD that is weakly expressed on fresh blood monocytes but is up-modulated by stimulation of monocytes with bacterial lipopolysaccharide, muramyl dipeptide, or phorbol compounds. Mo3e is also expressed by human myeloid cell lines, U-937 and HL-60, that have been stimulated in culture by biologically active phorbol diester compounds.

Antibodies, Monoclonal↗
PubMed1986

Neutrophil-induced injury of rat pulmonary alveolar epithelial cells.

The damage to pulmonary alveolar epithelial cells that occurs in many inflammatory conditions is thought to be caused in part by phagocytic neutrophils. To investigate this process, we exposed monolayers of purified rat alveolar epithelial cells to stimulated human neutrophils and measured cytotoxicity using a 51Cr-release assay. We found that stimulated neutrophils killed epithelial cells by a process that did not require neutrophil-generated reactive oxygen metabolites. Pretreatment of neutrophils with an antibody (anti-Mo1) that reduced neutrophil adherence to epithelial cells limited killing. Although a variety of serine protease inhibitors partially inhibited cytotoxicity, we found that neutrophil cytoplasts, neutrophil lysates, neutrophil-conditioned medium, purified azurophilic or specific granule contents, and purified human neutrophil elastase did not duplicate the injury. We conclude that stimulated neutrophils can kill alveolar epithelial cells in an oxygen metabolite-independent manner. Tight adherence of stimulated neutrophils to epithelial cell monolayers appears to promote epithelial cell killing.

Animals↗
PubMed1986

Mononuclear phagocyte activation: activation-associated antigens.

Mononuclear phagocyte activation is characterized by alterations in cellular metabolism and plasma membrane composition. In rodent and human systems, antibodies (conventional heteroantibodies or monoclonal reagents) that identify plasma membrane antigens selectively expressed by activated macrophages and monocytes have been generated. Among these activation-associated determinants is Mo3e (p50,80), a protease-sensitive antigen that is expressed by human monocytes activated in culture by exposure to bacterial lipopolysaccharide, muramyl dipeptide, or phorbol myristate acetate (PMA) (as well as other biologically active phorbol compounds). Mo3e is also expressed by the monoblastic cell line U-937 after culture in medium containing PMA and other pharmacological activators of protein kinase C (4 beta-phorbol-12,13-dibutyrate, 4 beta-phorbol-12,13-didecanoate, mezerein, and cell-permeable 1,2-diacylglycerol). The human promyelocytic cell line HL-60 becomes Mo3e positive after exposure in vitro to certain inducers of monocytic differentiation (PMA, dibutyryl cyclic AMP, and cholera toxin plus 3-isobutyl-1-methylxanthine). The surface expression of Mo3e is blocked by inhibitors of protein synthesis, N-linked glycosylation, and protein kinase activation, as well as by ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid and calcium antagonists. These data suggest the involvement of glycoprotein synthesis, protein kinase activation, and calcium ions in the stimulated expression of Mo3e by activated human mononuclear phagocytes. Anti-Mo3e antibody blocks the human monocyte response to migration inhibitory factor (MIF), which indicates an association between the expression of Mo3e antigen and responsiveness to MIF.

Animals↗
PubMed1986

Immunologic classification of leukemia and lymphoma.

Important insights into leukocyte differentiation and the cellular origins of leukemia and lymphoma have been gained through the use of monoclonal antibodies that define cell surface antigens and molecular probes that identify immunoglobulin and T cell receptor genes. Results of these studies have been combined with markers such as surface membrane and cytoplasmic immunoglobulin on B lymphocytes, sheep erythrocyte receptors on T lymphocytes, and cytochemical stains. Using all of the above markers, it is now clear that acute lymphoblastic leukemia (ALL) is heterogeneous. Furthermore, monoclonal antibodies that identify B cells, such as the anti-B1 and anti-B4 antibodies in combination with studies of immunoglobulin gene rearrangement, have demonstrated that virtually all cases of non-T-ALL are malignancies of B cell origin. At least six distinct subgroups of non-T-ALL can now be identified. T-ALL is subdivided by the anti-Leu-9, anti-Leu-1, and antibodies that separate T lymphocyte subsets into three primary subgroups. Monoclonal antibodies are also useful in the subclassification of non-Hodgkin's lymphoma, and certain distinct markers can be correlated with morphologic classification. The cellular origin of the malignant Reed-Sternberg cell in Hodgkin's disease remains uncertain. A substantial number of investigators favor a myelocyte/macrophage origin based on cytochemical staining; however, consistent reactivity with antimonocyte reagents has not been demonstrated. Although monoclonal antibodies are useful in distinguishing acute myeloid from acute lymphoid leukemias, they have less certain utility in the subclassification of acute myelogenous leukemia (AML). Attempts to subclassify AML by differentiation-associated antigens rather than by the French-American-British (FAB) classification are underway in order to document the potential prognostic utility of surface markers. Therapeutic trials using monoclonal antibodies in leukemia and lymphoma have been reported. Intravenous (IV) infusion of unlabeled antibodies is the most widely used method; transient responses have been demonstrated. Antibodies conjugated to radionuclides have been quite successful in localizing tumors of less than 1 cm in some studies. Therapy trials with antibodies conjugated to isotopes, toxins, and drugs are currently planned. Purging of autologous bone marrow with monoclonal antibodies and complement in vitro has been used in ALL and non-Hodgkin's lymphoma; preliminary data suggest that this approach may be an effective therapy and may circumvent many of the obstacles and toxicities associated with in vivo monoclonal antibody infusion.

Antibodies, Monoclonal↗
PubMed1986

Recent advances in the immunologic classification of leukemia.

Important insights into leukocyte differentiation and the cellular origins of leukemia have been gained through the use of monoclonal antibodies that define cell surface antigens and molecular probes that identify immunoglobulin and T cell receptor genes. Results of these studies have been combined with markers such as surface membrane and cytoplasmic immunoglobulin on B lymphocytes, sheep erythrocyte receptors on T lymphocytes, and cytochemical stains. Using all of the above markers, it is now clear that acute lymphoblastic leukemia (ALL) is heterogeneous. Although monoclonal antibodies are useful in distinguishing acute myeloid from acute lymphoid leukemias, they have less certain usefulness in the subclassification of acute myelogenous leukemia (AML). Attempts to subclassify AML by differentiation-associated antigens rather than by the French-American-British (FAB) classification are underway in order to document the potential prognostic usefulness of surface markers.

Antibodies, Monoclonal↗
PubMed1986

Expression of specific granule markers on the cell surface of neutrophil cytoplasts.

The widespread assumption that cytoplasts generated from human polymorphonuclear leukocytes (PMNs) are vesicles consisting solely of cytoplasm surrounded by plasma membrane and devoid of granule activity remains to be tested. PMN cytoplasts were prepared by centrifugation of intact cells on a Ficoll step gradient in the presence of cytochalasin B. Two granule membrane markers, Mol, a fluorometrically detectable antigen, and cytochrome b, both of which have been shown to translocate to the plasma membrane during granule release, were compared for their activity in cytoplasts and intact PMNs. We found that the amount of Mol detected on the plasma membrane of intact PMNs, as compared with other membrane markers (such as antigens LFA-1 and beta 2m), increased 1.6-fold upon exposure of PMNs to Ficoll plus cytochalasin B prior to centrifugation. Another twofold increase in Mol expression occurred upon cytoplast preparation. Release of the granule enzymes, vitamin B12-binding protein, and lysozyme were also followed and correlated well (r = .78 and .92) with the amount of Mol antigen present on the cell surface. Cytochrome b was also found to be higher (1.4-fold) on plasma membranes isolated from cytoplasts than on plasma membranes isolated from intact control cells. These results indicate that some fusion of granule membranes and plasma membranes occurred during treatment of PMNs with Ficoll plus cytochalasin b and during cytoplast preparation.

Adult↗
PubMed1986

Expression of a granule membrane marker on the surface of neutrophils permeabilized with digitonin. Correlations with Ca2+-induced degranulation.

The authors have previously shown that human neutrophils can be permeabilized with the cholesterol-complexing agent digitonin and that these cells can be induced to secrete granule contents by increasing free Ca2+ concentrations. In the studies reported here, the authors wished to determine whether secretion of granule constituents correlated with the appearance of an immunologic marker for granule membranes on the surface of the permeabilized neutrophils. For this purpose, we used flow cytometry and two fluorometrically identifiable markers, Mo1 (a granule membrane marker) and beta 2-microglobulin (beta 2m) (a plasma membrane marker). It was found that the ratio of Mo1/beta 2m increased for permeabilized neutrophils which were exposed to micromolar concentrations of free Ca2+. This increase in the detectable surface concentration of Mo1 was accompanied by the release of lysozyme, vitamin B12 binding protein, and beta-glucuronidase into the medium. Statistical analysis showed a very strong correlation between granule secretion and the Mo1/beta 2m ratio. These data thus suggest that granule membrane components were being introduced into the plasma membrane during Ca2+-induced granule discharge; this in turn suggests that secretion by permeabilized neutrophils represents true degranulation.

Adult↗
PubMed1986

Regulation of human monocyte surface antigen expression. I. Up-modulation of Mo3e antigen expression on U-937 and HL-60 cells stimulated by pharmacologic activators of protein kinase C.

Mo3e is a protein (p 50,80) that is expressed on the surface of human monocytic cells after exposure in vitro to soluble activating factors that include bacterial lipopolysaccharide, muramyl dipeptide, and phorbol myristate acetate (PMA). The surface expression of Mo3e may represent a cellular event that occurs in response to the formation of "secondary messengers" that include diacylglycerol, inositol trisphosphate, and calcium ions. This postulate is based on the stimulatory effect of agents that can mimic the activity of endogenous diacylglycerol (PMA and other biologically active phorbol compounds, mezerein, and L-alpha-1,2 dioctanoylglycerol) and inositol trisphosphate (ionomycin) on Mo3e expression by U-937 and HL-60 cells. The inhibitory effect of phospholipid-active calmodulin inhibitors (trifluoperazine, chlorpromazine, and dibucaine), calcium antagonists (nicardipine and TMB-8), and EGTA further support the involvement of phospholipid- and calcium-dependent protein kinase (protein kinase C) and calcium ions in the up-modulation of Mo3e surface expression.

Antigens, Surface↗
PubMed1985

Increased expression of an adhesion-promoting surface glycoprotein in the granulocytopenia of hemodialysis.

To identify the mechanisms accounting for hemodialysis-induced granulocytopenia, we undertook quantitative kinetic studies of a granulocyte-adhesion-promoting surface glycoprotein (Mo1). In eight patients undergoing maintenance hemodialysis, there was a fivefold increase in the mean cell-surface expression of Mo1 within 15 minutes after the start of dialysis with a new cuprophane membrane. The peak increase in surface Mo1 coincided with the maximal drop in neutrophil count and with the peak rise in the plasma levels of the complement-activation products C5a desArg and C3a desArg. During dialysis on a membrane being reused for the fifth time, no significant complement activation, no increase in Mo1 expression, and no change in neutrophil count were seen. C5a desArg (but not C3a desArg) induced a comparable increase in Mo1 expression on normal granulocytes in vitro at concentrations similar to those measured in vivo. Chemotactic peptide-induced granulocyte aggregation (a reflection of increased cell-to-cell adhesiveness) was specifically blocked by mouse monoclonal antibodies to Mo1 in vitro. These data suggest that the increased expression of Mo1 on granulocytes in vivo is in part mediated by C5a (and C5a desArg). The quantitative increase in granulocyte-surface Mo1 may provide a mechanism for initiating leukoaggregation, sequestration of granulocytes, and neutropenia during hemodialysis.

Adult↗
PubMed1985

Immunohistologic analysis of a human pulmonary alveolar macrophage antigen.

PAM1 is a 200-kDa polypeptide antigen present on lavaged human alveolar macrophages but not on monocytes, peritoneal macrophages, breast milk macrophages, or other normal hematopoietic cells studied by flow cytometry. We have characterized the distribution of expression of this antigen by cells in tissues by using immunohistologic techniques. Normal and diseased lung as well as lymph nodes, spleen, kidney, liver, GI tract, and skin were studied. PAM1 was expressed strongly on the surface and weakly in the cytoplasm of most alveolar macrophages in all 15 of the lung specimens. Occasional interstitial macrophages had weak to moderate staining for this antigen but the majority did not stain. The distribution, pattern, and intensity of staining for PAM1 was the same in normal lung specimens and those with interstitial pneumonitis, despite the increase in mononuclear cells in the latter. Dermal histiocytes and Kuppfer cells expressed PAM1 weakly. Sinus histiocytes in lymph nodes were moderately to strongly positive. Although lymphoid cell suspensions (tonsil) were negative by flow cytometry, five of six lymph nodes had positive cells by immunohistology. PAM1 was also detected on endothelial cells of splenic sinusoids in all 6 specimens but not on any other endothelium. Hence, while PAM1 is expressed most strongly on alveolar macrophages, it can also be demonstrated in other locations using sensitive immunohistologic techniques. Since circulating monocytes are antigen negative and some lung interstitial macrophages bear antigen, PAM1 may be a useful marker for studies of the differentiation of mononuclear cells in the lung.

Antibodies, Monoclonal↗
PubMed1985

The modulated expression of Mo5, a human myelomonocytic plasma membrane antigen.

Mo5 is a 94-kd protein antigen expressed by human peripheral blood monocytes, neutrophils, and by all bone marrow myeloperoxidase-positive myeloid precursors (promyelocytes, myelocytes, metamyelocytes, and bands). Mo5 is borne by the malignant cells of 74% of patients (N = 27) with acute monocytic leukemia (French-American-British [FAB] group M4, M5), and 50% of patients (N = 38) with acute granulocytic leukemia (FAB M1, M2, and M3). Nonmyeloid cells in peripheral blood and bone marrow are Mo5-negative. The surface expression of Mo5 by myeloid cells is modulated by several experimental conditions: Exposure of neutrophils to calcium ionophore (1 mumol/L, 37 degrees C, ten minutes) under conditions resulting in degranulation of specific granules produces a three- to fourfold increase in the plasma membrane density of Mo5 antigen. This suggests that, in neutrophils, there is an intracellular pool of Mo5 antigen, which may be associated with specific granules, and that granule-associated Mo5 is translocated to the plasma membrane upon degranulation. Conversely, incubation of monocytes, neutrophils, U-937, and Mo5-positive leukemia cells in medium containing anti-Mo5 monoclonal antibody results in a significant decrease in surface Mo5 expression. This loss of surface Mo5 is a rapid, temperature-dependent process (occurring within 30 minutes at 37 degrees C) that is produced by divalent anti-Mo5 immunoglobulin [F(ab')2 but not F(ab)]. After down-modulation, Mo5 is reexpressed by monocytes within 48 hours. Mo5 is therefore a human myelomonocytic differentiation antigen whose expression is modulated up or down depending on the nature of extracellular stimuli.

Adjuvants, Immunologic↗
PubMed1985

Mb1, a plasma membrane antigen selectively expressed by U-937 cells.

To examine the plasma membrane characteristics of an immature monocytic cell capable of proliferation, we have developed a murine monoclonal antibody that identifies an antigen, Mb1, found on the surface of U-937. In immunofluorescence analyses, Mb1 is not expressed by peripheral blood monocytes (freshly isolated, lymphokine-activated, or cultured for seven days), neutrophils, or any other circulating element. It is also absent on human bone marrow mononuclear cells, including the CFU-GM. Among a series of malignant cells from 50 patients with acute myeloid leukemia (including 22 with monocytic or myelomonocytic leukemia), no Mb1 expression was detected. Continuous human cell lines of B or T cell origin were also negative, as were the myeloid lines HL-60 and K562. Apart from U-937, which uniformly expresses Mb1 in high antigen density, only KG-1 (a myeloblastic line) exhibits Mb1 in low antigen density. Exposure of U-937 to phorbol diester (TPA) under conditions that induce features of macrophage differentiation (including the expression of Mo1) results in a significant reduction in Mb1 expression. Mb1 expression is also reduced as a result of culture of U-937 in medium containing anti-Mb1 antibody (antigenic modulation). On sodium dodecyl sulfate-polyacrylamide gel electrophoresis of radiolabeled immunoprecipitates, Mb1 appears to be a dimeric protein with an estimated molecular weight of 80 kd (43 kd under reducing conditions). Antigenic activity on U-937 is destroyed by treatment with trypsin or papain but is regenerated after 24 hours' culture in enzyme-free medium. Mb1 is a constituent plasma membrane protein of U-937, and its degree of expression relates to the state of cellular differentiation.

Antibodies, Monoclonal↗
PubMed1985

Deficiency of two human leukocyte surface membrane glycoproteins (Mo1 and LFA-1).

Structural and functional features of a novel disorder characterized by recurrent bacterial infections are reviewed. This disease is associated with a number of phagocyte adhesion defects. In 10 patients, phenotypic analysis with monoclonal antibodies (MAb) revealed the same basic defect in all patients: deficiency of at least two leukocyte surface glycoproteins, Mo1 and LFA-1. These two antigens have distinct alpha subunits (Mo1 alpha = 155 kilodaltons, LFA-1 alpha = 177 kilodaltons) noncovalently linked to a common beta subunit (94 kilodaltons). Mo1 is closely associated with or identical to a receptor for the iC3b fragment of the third component of complement. LFA-1 is involved in lymphocyte proliferation, cytotoxicity, and natural killing. MAb directed to this family of glycoproteins induce functional defects in normal cells similar to those observed in deficient cells. In normal cells, the surface expression of these glycoproteins is regulated by the state of cell activation. Mitogens and alloantigens significantly increase the surface expression of LFA-1 on T lymphocytes. Stimuli that induce degranulation in neutrophils increase the surface expression of Mo1. In all patients with combined Mo1, LFA-1 deficiency, the predominant clinical manifestations were more characteristic of a phagocyte than a lymphocyte disorder. In vitro studies, however, reveal significant defects in phytohemagglutinin-induced proliferation that are more apparent at lower concentrations of the lectin. In some families, more than one sibling is affected. Intermediate levels of Mo1 were observed on granulocytes from both parents of one child. In one family, however, only the mother had significantly reduced levels of Mo1, which indicates heterogeneity in the inheritance of this disorder.

Animals↗
PubMed1985

Bacterial lipopolysaccharide, phorbol myristate acetate, and muramyl dipeptide stimulate the expression of a human monocyte surface antigen, Mo3e.

Exposure of mononuclear phagocytes to bacterial lipopolysaccharide (LPS), phorbol myristate acetate (PMA), or muramyl dipeptide (MDP) is known to stimulate a variety of cellular activities that include increases in phagocytosis, oxidative metabolism, synthesis and secretion of monokines, and cytotoxicity of microbes and tumor cells. We now report that culture of human peripheral blood monocytes in medium containing LPS, phorbol compounds, or MDP also results in the acquired expression of a plasma membrane antigen. Mo3e, as identified by a murine monoclonal antibody. Mo3e is barely detectable (by immunofluorescence flow cytometry) on freshly isolated monocytes, but is expressed in high antigen density after exposure of cells to E. coli, Salmonella minnesota, or Serratia marcescens LPS (at concentrations exceeding 0.1 ng/ml), PMA (and other biologically active phorbol compounds) (0.5 to 1 X 10(-8) M), or MDP (0.01 to 1 X 10(-6) M). Mo3e expression stimulated by LPS is prevented by pretreatment of LPS with polymyxin B, suggesting that the lipid A portion of LPS is responsible for Mo3e induction (polymyxin B has no effect on Mo3e expression stimulated by PMA or MDP). Culture of monocytes in medium containing protein synthesis inhibitors (or at 4 degrees C) blocks the acquisition of Mo3e. Recombinant IFN-gamma, which is also known to "activate" mononuclear phagocytes, does not stimulate Mo3e expression, although both LPS and IFN induce enhanced expression of monocyte Ia antigen. Analogous to their stimulatory effect on monocytes, LPS and PMA induce Mo3e expression by the human monocytic cell line, U-937. On the basis of these observations, Mo3e may represent an immunologic marker for monocyte activation stimulated in vitro by LPS, PMA (and related compounds), and MDP.

Acetylmuramyl-Alanyl-Isoglutamine↗