Search PubMed⌕ Search

Biomedical subjects

R Snyderman

Publications and source records attributed to R Snyderman.

At least 199 records · Page 11Linked to original sources
PubMed1977

Specific receptor sites for chemotactic peptides on human polymorphonuclear leukocytes.

Synthetic N-formylmethionyl peptides are chemotactic attractants for human polymorphonuclear leukocytes. The well-defined structure-activity relationship of these peptides in eliciting a chemotactic response suggests that the interaction of the peptides with a specific cellular binding site may initiate chemotaxis. By using tritiated N-formylmethionyl-leucyl-phenylalanine (fMet-Leu-[3H]Phe), a potent chemotactic peptide with high specific radioactivity, we have directly identified binding sites on human polymorphonuclear leukocytes. Binding of fMet-Leu-[3H]Phe to polymorphonuclear leukocytes is rapid (t1/2 less than 2 min) and reversible. The equilibrium dissociation constant (KD) for the interaction of fMet-Leu-[3H-A1Phe with the binding site is 12-14 nM at 37 degrees. The number of binding sites is approximately 2000 per cell. The specificity of the binding sites for a series of N-formylmethionyl peptides exactly reflects the specificity of the chemotactic response to the peptides in that they compete for the binding sites and initiate chemotaxis with the same order of potency (fMet-Leu-Phe greater than fMet-Met-Met greater than fMet-Phe greater than fMet-Leu greater than fMet),fPhe-Met is a competitive antagonist of the chemotactic activity of N-formylmethionyl peptides and has a calculated KD of 6x10-5 M. FPhe-Met also half-maximally inhibits binding of fMet-Leu[3H]Phe binding was the highest in polymorphonuclear leukocytes. No binding of fMet-Leu-[3H]Phe to human erythrocytes could be detected. These data indicate that fMet-Leu-[3H]Phe can be used to identify binding sites for chemotactic peptides on human polymorphonuclear leukocytes. It is likely that these binding sites initiate the specific response of motile cells to N-formylmethionyl peptides.

Binding Sites↗
PubMed1977

Abnormalitieis of monocyte chemotaxis in patients with melanoma: effects of immunotherapy and tumor removal.

The chemotactic responsiveness of peripheral blood monocytes was studied before and after immunotherapy was administered to 56 patients with melanoma. Abnormal chemotaxis was found in 36 patients (64%) prior to treatment; this abnormality correlated with severity of disease and prognosis. Immunotherapy with BCG and sensitized autologous lymphocytes and X-irradiated melanoma cells or surgical removal of the neoplasm both reduced the percentage of patients with abnormal chemotactic responses. The best prognosis was found for those patients who had normal chemotaxis prior to therapy. The data support the hypothesis that abnormalities of monocyte function might render the host less likely to destroy developing neoplasms and that malignant tumors themselves might affect monocyte function.

Adolescent↗
PubMed1977

Macrophage migratory dysfunction in cancer. A mechanism for subversion of surveillance.

There is considerable evidence to suggest that macrophages participate in host resistance to the development and spread of cancer. We have, therefore, studied monocytemacrophage function in humans and animals with neoplasms. Approximately 60% of patients with various types of cancer were found to have abnormal monocyte chemotactic responsiveness in vitro, and abnormal chemotaxis was an indicator of poor prognosis in patients with melanoma. By studying patients before and after surgery, it was found that abnormal chemotactic responses normalized within weeks after removal of malignant tumors, indicating that a neoplasm itself might affect the host's monocyte chemotactic responsiveness. Subsequent studies using transplantable neoplasms in mice substantiated this hypothesis in that macrophage accumulation in vivo as well as macrophage chemotactic responsiveness in vitro was depressed in animals during the early phases of tumor growth. This depression of macrophage function could be attributed to a low-molecular-weight factor contained in murine neoplasms, which when given to normal mice was extremely potent in depressing peritoneal macrophage accumulation and chemotaxis but, paradoxically, enhanced phagocytosis. The serum of tumor-bearing mice also contained potent inhibitory activity for macrophage accumulation. In contrast to the effects on macrophages, granulocyte accumulation in vivo and chemotaxis in vitro was not depressed by the presence of a neoplasm or the administration of the factor from neoplasms. By releasing factors which depress macrophage migratory function, neoplasms may protect themselves from immunologically mediated host destruction during the early phases of tumor growth.

Animals↗
PubMed1976

The chemotactic attraction of human fibroblasts to a lymphocyte-derived factor.

A quantitative assay that measures fibroblast chemotaxis in vitro is described. Application of this technique has revealed that peripheral blood lymphocytes stimulated by antigen or mitogen in vitro produce a factor that is chemotactic for human dermal fibroblasts. This lymphocyte-derived chemotactic factor for fibroblasts (LDCF-F) is different from the lymphokine that is chemotactic for monocytes or macrophages. Macrophages are required for the generation of LDCF-F by T lymphocytes stimulated by phytohemagglutinin. The fibroblast chemotactic factor is heat stable (56 degrees C for 30 min), trypsin sensitive, and neuraminidase resistant. LDCF-F could function to attact connective tissue fibroblasts to sites at which cell-mediated immune reactions are occurring in vivo.

Cell Line↗
PubMed1976

Calcium influx requirement for human neutrophil chemotaxis: inhibition by lanthanum chloride.

Calcium fluxes of human neutrophils measured in the presence of chemotactically active serum showed a marked stimulation of calcium-45 uptake from the media. Chemotactically inactive serum did not cause an influx of calcium. The magnitude of the calcium influx due to activated serum is sufficient to trigger contractile systems previously described in muscle cells. Lanthanum chloride inhibited the chemotactic response of human neutrophils to activated serum. Lanthanum in concentrations that suppressed chemotaxis also inhibited the calcium influx caused by activated serum. Lanthanum in concentrations that suppressed chemotaxis also inhibited the calcium influx caused by activated serum. The data support a direct role of calcium influx in chemotaxis of neutrophils.

Biological Transport↗
PubMed1976

An inhibitor of macrophage chemotaxis produced by neoplasms.

The accumulation of macrophages at neoplastic sites may be an important event in immunologically mediated tumor killing. The implantation of syngeneic neoplasms in mice, however, was found to depress the animal's ability to localize macrophages at inflammatory sites. A low-molecular-weight (6,000 to 10,000) factor released by growing neoplasms that inhibits the accumulation of macrophages in vivo and chemotactic responsiveness in vitro was identified. The factor is active in the inhibition of macrophages and is ineffectual at retarding the migration of polymorphonuclear leukocytes. Neoplastic cells may thus abrogate immunosurveillance by releasing products that prevent potentially tumoricidal macrophages from accumulating at sites of developing malignancies.

Animals↗
PubMed1976

Prostaglandins and inflammation: enhancement of monocyte chemotactic responsiveness by prostaglandin E2.

The effects of prostaglandins on human monocyte chemotaxis were studied in vitro. None of the prostaglandins tested, including members of the A, B, E or F series, were chemotactic for monocytes. Prostaglandin E2 however, enhanced the chemotactic responsiveness of monocytes to complement - activated human serum by almost 200%. The enhancement of chemotaxis was not directly related to the ability of PGE2 to raise intracellular cyclic AMP levels. These studies support a role for prostaglandins as modulators of the inflammatory response.

Chemotaxis↗
PubMed1976

Identification of beta-adrenergic receptors in human lymphocytes by (-) (3H) alprenolol binding.

Human lymphocytes are known to posessess a catecholamine-responsive adenylate cyclase which has typical beta-adrenergic specificity. To identify directly and to quantitate these beta-adenergic receptors in human lymphocytes, (-) [3H] alprenolol, a potent beta-adrenergic antagonist, was used to label binding sites in homogenates of human mononuclear leukocytes. Binding of (-) [3H] alprenolol to these sites demonstrated the kinetics, affinity, and stereospecificity expected of binding to adenylate cyclase-coupled beta-adrenergic receptors. Binding was rapid (t1/2 less than 30 s) and rapidly reversible (t1/2 less than 3 min) at 37 degrees C. Binding was a saturable process with 75 +/- 12 fmol (-) [3H] alprenolol bound/mg protein (mean +/- SEM) at saturation, corresponding to about 2,000 sites/cell. Half-maximal saturation occurred at 10 nM (-) [3H] alprenolol, which provides an estimate of the dissociation constant of (-) [3H] alprenolol for the beta-adrenergic receptor. The beta-adrenergic antagonist, (-) propranolol, potently competed for the binding sites, causing half-maximal inhibition of binding at 9 nM. beta-Adrenergic agonists also competed for the binding sites. The order of potency was (-) isoproterenol greater than (-) epinephrine greater than (-)-norepinephrine which agreed with the order of potency of these agents in stimulating leukocyte adenylate cyclase. Dissociation constants computed from binding experiments were virtually identical to those obtained from adenylate cyclase activation studies. Marked stereospecificity was observed for both binding and activation of adenylate cyclase. (-)Stereoisomers of beta-adrenergic agonists and antagonists were 9- to 300-fold more potent than their corresponding (+) stereoisomers. Structurally related compounds devoid of beta-adrenergic activity such as dopamine, dihydroxymandelic acid, normetanephrine, pyrocatechol, and phentolamine did not effectively compete for the binding sites. (-) [3H] alprenolol binding to human mononuclear leukocyte preparations was almost entirely accounted for by binding to small lymphocytes, the predominant cell type in the preparations. No binding was detectable to human erythrocytes. These results demonstrate the feasibility of using direct binding methods to study beta-adrenergic receptors in a human tissue. They also provide an experimental approach to the study of states of altered sensitivity to catecholamines at the receptor level in man.

Adenylyl Cyclases↗
PubMed1976

A role for adenosine deaminase in human monocyte maturation.

The occurrence of a deficiency of adenosine deaminase (ADA) activity in some patients with severe combined immunodeficiency suggests a possible relationship between the activity of ADA and the aberration of the immune system. To help delineate the function of ADA in the immune response we have examined its role in monocyte maturation. When incubated in vitro, peripheral blood monocytes transformed, within 3 days, to macrophagea as assessed by phase-contrast microscopy and an increase in the specific activity of the lysosomal enzyme acid phosphatase. The specific activity of ADA increased as much as ninefold, reaching a peak after the 1st day in culture, while the activities of other enzymes involved in the purine salvage pathway were not altered. Sucrose density ultracentrifugation of extracts prepared immediately after the isolation of monocytes revealed the presence of two forms of ADA with molecular weights of approximately 30,000 and 110,000. The increase in ADA specific activity during monocyte cultivation correlated with an increase in the activity of the smaller molecular species. A specific inhibitor ADA, erythro-9-(2-hydroxy-3-nonyl) adenine, prevented the increase in acid phosphatase activity, as well as the morphological changes associated with the monocyte maturation. These data suggest a role for ADA in monocyte to macrophage maturation. In view of the central role of macrophages in immune function, this observation may relate to the association of combined immunodeficiency and a deficiency of this enzyme.

Acid Phosphatase↗
PubMed1976

Human lymphocyte motility: normal characteristics and anomalous behavior of chronic lymphocytic leukemia cells.

The characteristics of human lymphocyte motility and its relationship to the redistribution of surface membrane antigens (capping) are poorly defined. Since chronic lymphocytic leukemia (CLL) cells cap poorly when compared with normal human lymphocytes, this study was undertaken to compare the motility of these two cell types. A modification of the Boyden chamber system was employed to quantify lymphocyte motility by placing lymphocyte suspensions on 8-mum convoluted-pore nitrocellulose filters and measuring the depth of migration of the cells into the filter at 37 degrees C. After 3 hr of incubation, CLL cells migrated significantly less into the filter than normal cells. Incubation in the presence of sodium azide or at 4 degrees C abolished all motility, indicating the active nature of the process. The relative motility of individual CLL patients' cells correlated best with the proportion of abnormal cells present as determined by surface receptor assays. The possibility that decreased cell motility in CLL was a reflection of enrichment by a "bone marrow-derived" (B cell) population was eliminated by the finding that normal B cells purified by gradient separation of rosetted cells migrated faster than normal T cells and considerably faster than CLL cells. Motility of normal and CLL lymphocytes was decreased by cytochalasin B and increased by colchicine, vincristine, and vinblastine. Thus, human lymphocyte motility appears to be dependent on microfilament integrity but not to require the colchicine-sensitive cytoskeleton. The decreased motility of CLL cells is the result of an intrinsic cell abnormality, but this finding cannot fully explain the decreased capping, since in human lymphocytes the latter is not prevented by an inhibitor of motility.

Adult↗
PubMed1976

Effect of virus infection on the inflammatory response. Depression of macrophage accumulation in influenza-infected mice.

To better define the mechanisms by which viruses depress immune function, the effect of influenza infection on the ability of macrophages to accumulate at sites of inflammation was determined. Mice were inoculated with virus, and their inflammatory response measured in vivo by counting the number of leukocytes which accumulated in the peritoneal cavity 2 days after an intraperitoneal injection of phytohemagglutinin. Mice infected with influenza had a 57% and 65% depression of total leukocyte and macrophage accumulation, respectively, as compared to the response of uninfected mice. In contrast, bacterial pneumonia did not produce a decrease in the macrophage response. This indicated that the depression was produced by the virus infection rather than being a nonspecific phenomenon accompanying any inflammatory focus in the lung. The in vitro chemotactic responsiveness of normal peritoneal macrophages incubated with infectious influenza virus was 53% of normal. These experiments suggest that influenza infection may depress a host's ability to mobilize macrophages to inflammatory sites in vivo by inhibiting their chemotactic responsiveness.

Animals↗
PubMed1976

Effects of neoplasms on inflammation: depression of macrophage accumulation after tumor implantation.

The local accumulation of macrophages at sites of neoplasms may be a critical event in immunologically mediated tumor killing. Individuals with neoplasms, however, have been noted to have depressed monocyte chemotactic responsiveness in vitro. To determine the effect of neoplasms on macrophage migration, mice were implanted subcutaneously with either sarcoma or hepatoma cells and their macrophage migratory function quantified in vivo and in vitro. The ability of tumor-bearing animals to mobilize macrophages to an inflammatory site in vivo was depressed by as much as 61% by 6 days after tumor implantation. The in vitro chemotactic responsiveness of macrophages recovered from the peritoneal cavities of tumor-bearing animals was also markedly depressed. Macrophage migration was not affected by implantation of normal syngeneic or allogeneic tissues. In addition, the accumulation of polymorphonuclear leukocytes in vivo was not depressed in tumor-bearing animals. These findings suggest that neoplasms themselves may depress the host's ability to localize macrophages at inflammatory sites in vivo and thereby hinder immunologically mediated tumor destruction.

Animals↗
PubMed1976

Depression of macrophage function by a factor produced by neoplasms: a merchanism for abrogation of immune surveillance.

The possibility that macrophages mediate surveillance against the development of neoplasms has been reciving increasing support. The acquisition, by neoplastic cells, of the capacity to subvert macrophage function may be an important mechanism by which they escape destruction by the host and become established tumors. Indeed, animals implanted with syngeneic neoplasms developed depressed macrophage migratory ability in vivo and chemotactic responsiveness in virto. It therefore seemed plausible that neoplasms might be capable of producing inhibitors of macrophage function. The present report describes the identification of such a low molecular weight (6,000 to 10,000), heat-stable inhibitor of murine macrophage accumulation in vivo and chemotaxis in vitro. The inhibitor of macrophages was present in four different murine neoplasms, but not present in normal liver, spleen, or inflammatory exudate cells and did not affect PMN chemotaxis in vitro. When given with low numbers of neoplastic cells, the inhibitor increased both the frequency of tumor development and rate of tumor growth. By producing inhibitors of macrophage function, neoplasms may escape initial host surveillance mechanisms.

Animals↗
PubMed1975

Depressed monocyte chemotaxis during acute influenza infection.

The chemotactic responsiveness of monocytes from patients with serologically proven influenza infection has been quantified in vitro. Individuals with acute influenza had a significant (P less than 0-001) depression of monocyte chemotaxis. The depression ranged from 40% to 72% during acute infection but rose to normal by three weeks after recovery. When isolated mononuclear leucocytes from the recovered patients were incubated with the infecting strain of virus (Port Chalmers), a 49-54% inhibition of chemotaxis was obtained. These findings support the hypothesis that the altered immune responsiveness and increased predisposition to superinfections found frequently in patients with influenza can be due to the ability of the virus to depress monocyte function.

Acute Disease↗