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At least 721 records · Page 40Linked to original sources
PubMed1991

Competitive effect of anti-HLA class I monoclonal antibody (01.65) and N-N-staurosporine on prolipherative response of PHA activated T-lymphocytes.

N-N-Staurosporine (STAR) inhibits in a dose dependent manner Tritiated-Thymidine (3H-TdR) incorporation in phytohemagglutinin (PHA) activated Peripheral Blood Mononuclear Cells (PBMC) treated with anti-HLA class I monoclonal antibody (MAb) 01.65 and its effect results competitive with MAb 01.65. Cytosolic and particulate Protein Kinase C (PKC) have been studied. Only when PKC particulate activity is no more detectable, the effect of STAR on 3H-TdR incorporation is evident.

Alkaloids↗
PubMed1990

C-fos, c-myc and IL-2R mRNA expression in PHA activated T lymphocytes treated with a monoclonal anti-HLA class I antibody (MAb 01.65).

Monoclonal anti HLA class I antibodies inhibit the proliferative response of PHA-stimulated T lymphocytes. We studied the effects of MAb 01.65 anti-HLA class I on c-fos, c-myc and IL-2R mRNA expression. We found that MAb treatment does not modify either c-fos mRNA levels observed after 10 minutes to 3 hrs or the early c-myc mRNA expression revealed after 1 to 6 hrs, but decreases the intensity of autoradiographic signals of late c-myc and IL-2R mRNA expression. Since we had previously ascertained that MAb 01.65 treatment induces a decrease in PKC enzymatic activity after few minutes, the correlation of that result with the data presented in this paper will be discussed.

Antibodies, Monoclonal↗
PubMed1990

Cadmium, nickel, chromium and lead accumulate in human lymphocytes and interfere with PHA-induced proliferation.

The in vitro effect of five toxic metals (cadmium, lead, nickel, barium, chromium III and VI) on PHA-induced blastogenesis in human lymphocytes was investigated by [3H]-thymidine incorporation. With the exception of hexavalent chromium, the metals tested were in the chloride forms. The levels of metals associated with lymphocytes were measured under our experimental procedure. An inhibitory effect was found when cadmium was added at doses which closely approximate those of occupationally exposed subjects. Hexavalent chromium and nickel showed a biphasic pattern, with a stimulatory effect at the lowest concentrations tested (10(-8)-10(-6) mol/L) and an inhibitory effect on thymidine incorporation at concentrations higher than 10(-6) and 10(-4) mol/L, respectively. No effect was observed when lead, barium, and trivalent chromium were added to the culture medium. All metals showed the ability to enter the lymphocytes or to adhere to their surface, and the interaction appeared to be quite stable, with the exception of barium. The relationship between metal accumulation and [3H]-thymidine incorporation in the cells is discussed.

Adult↗
PubMed1979

Role of thymic hormone (THF) and of a thymic plasma recirculating factor (TPRF) in the modulation of human lymphocyte response to PHA and Con A.

The results presented here point to the possibility that calf thymus extracts contain, in addition to the thymic hormone (THF), a second component: thymic plasma recirculating factor (TPRF). THF, which is involved in the process of T cell maturation and has been characterized as a protein of m.w. 3000 eluted in the void volume of a G-10 Sephadex column (G-10-I), caused an increased level of intracellular cAMP in umbilical cord blood lymphocytes (UCBL). This is in agreement with our previous observation that THF plays a major role in the differentiation of T cells. The second active material, TPRF, also isolated from thymic extract, is of a molecular size below 500 and was eluted in a G-10 Sephadex column at the fourth protein peak; it seems to circulate in the blood. Previously, we had observed in impaired response of UCBL to PHA and Con A stimulation in the presence of dialyzed human plasma (DHP). Our present results indicate that this impaired response is restored exclusively by TPRF. A factor with TPRF-like activity was also isolated from the plasma of normal donors; yet it was not detected in the plasma of thymectomized patients suffering from myasthenia gravis (MG). This suggests that TPRF from plasma is thymus dependent. TPRF does not affect the level of intracellular cAMP in UCBL.

Concanavalin A↗
PubMed1990

Therapeutic activities of PHA-L4, the mitogenic isolectin of phytohemagglutinin.

Evidence is presented that suggests that PHA-L4 may exert the therapeutic effects of a theoretical ideal biological response modifier through its ability to do the following: to assist remission induction in certain malignancies, to exhibit direct antitumor cytotoxic effects, to enhance antineoplastic effect of radiation and chemotherapy, to decrease the liability to malignant transformation, to promote differentiation and restore normal growth responses in neoplastic cells, to manifest minimal liability to suppressor activity that would inhibit tumor rejection or antitumor cytotoxicity, to repress graft rejection and graft-versus-host responses and amplify the immunosuppressive effects of other agents in allograft transplantations, to display a direct protective effect against damage from radiation and chemotherapy, to stimulate normal myelopoiesis, to reinforce responses against various infections, to amplify tumor immunogenicity, and to attract mononuclear cells to sites of injection or local application.

Adjuvants, Immunologic↗
PubMed1990

Cell kinetics of PHA-activated lymphocytes are slowed by prolonged hypertonic stress.

The effect of prolonged exposure to a hypertonic medium on human lymphocytes during mitogenic stimulation with phytohemagglutinin was investigated. The process of chromatin decondensation during the first 24 hrs stimulation (G0 to G1 transition) and the changes in kinetic parameters and the occurrence of chromosome aberrations from 48 hrs to 72 hrs of stimulation were studied. In HT medium, lymphocyte transition from G0 to G1 was slowed; there were fewer S-phase cells, after 48 hrs PHA stimulation, whereas after 72 hrs the resistant cells showed the same frequency of S-phase cells as the controls. The mitotic index was always smaller, and the frequency of G0/G1 cells larger. No significant increase in the frequencies of chromosome aberrations were found. These findings suggest that human peripheral lymphocytes can survive and grow in a hypertonic medium; chromosome damages, if not repaired, may be lethal, and only lymphocytes with normal karyotypes can survive for long times in the HT medium, although with modified kinetic characteristics.

Cell Cycle↗
PubMed1990

Interaction between endogenous opioids and IL-2 on PHA-stimulated human lymphocytes.

Endogenous opioids exert a variety of extra central nervous system (CNS) functions, including modulation of some human lymphocyte functions. The latter opioid activity may result in elevation of human natural killer (NK) function (i.e. by beta-endorphin), which is reversed by an opioid antagonist, Naloxone. Since recent evidence has suggested both structural and functional similarities between lymphokines known to elevate human NK function (interferon and interleukin-2) and endogenous opioids, we investigated if Naloxone could modulate lymphokine-enhanced human NK activity. Naloxone blunted, in a dose-dependent fashion, the NK-enhancing activity of peripheral blood lymphocytes or large granular lymphocytes by recombinant interferon-alpha (IFN-alpha) or interleukin-2 (IL-2). Naloxone decreased the uptake of radiolabelled IL-2 receptors. beta-endorphin also decreased the binding of radiolabelled IL-2 or IL-2 receptor-positive human lymphocytes. Finally, labelled Naloxone was inhibited from binding to phytohaemagglutinin (PHA)-stimulated lymphocytes by either beta-endorphin or IL-2. These findings strongly suggest that human lymphocyte receptors for opioid, IFN or IL-2 molecules, once occupied, have distinct influences on the alternate receptor. In addition, these data further strengthen the potential role of CNS-mediated influences on the human immune system.

Binding, Competitive↗
PubMed1989

Morphological characterization of the pathway of endocytosis and intracellular processing of transferrin and alpha-fetoprotein in human T lymphocytes stimulated with phytohemagglutinin (PHA).

Covalent conjugates of transferrin (Tf) and alpha-fetoprotein (AFP) with horseradish peroxidase (HRP) have been used to follow, at the ultrastructural level, the uptake and the intracellular pathway of these proteins in peripheral blood human lymphocytes stimulated by phytohemagglutinin (PHA) to blast formation. Both proteins enter specifically the cells via vesicles (60-70 nm in diameter) and endosomes. They are then observed in multivesicular bodies and tubular vesicular elements in the Golgi region. AFP is thus found in the same subcellular compartments as Tf and is probably also recycled, as most of the 125I-labeled protein leaves the cells undegraded. Unstimulated lymphocytes do not internalize significantly AFP-HRP. The uptake of a noncovalent conjugate of AFP-HRP and [3H]-arachidonic acid [3H-(20:4)] is usually poor, at 37 degrees C, in unstimulated lymphocytes as well as, at 4 degrees C, in lymphocytes stimulated for 72 h. Stimulated lymphocytes incubated at 37 degrees C with the radioactive conjugate show a heavy labeling of cell organelles and more particularly of lipid droplets. AFP could regulate the intracellular delivery of fatty acid molecules.

Endocytosis↗
PubMedDate not supplied

[A comparative study of the micronucleus test and chromosome aberrations in PHA-stimulated human lymphocytes].

A dose dependence of the number of cells with chromosome aberrations was studied in PHA-stimulated donor's peripheral blood lymphocytes irradiated in vitro with doses of 10-400 cGy. In studying the number of chromosome aberrations and percentage of cells with micronuclei in parallel cultures no correlation was found between these indices within the groups exposed to a similar radiation dose.

Adult↗
PubMed1989

Effect of HBV antigens and their immune complexes on the PHA induced lymphocyte proliferation. Modulatory influence on interleukin-2 activity.

Studies were undertaken to evaluate immunomodulating properties of Hepatitis B virus (HBV) preparations: HBsAg, HBeAg and their complexes: HBsAg-IgG and HBeAg-IgG, on PHA-induced lymphocyte proliferation. Cells were obtained from blood of healthy individuals, serologically negative for HBV markers. HBV preparations were purified from sera of children with HBV-mediated glomerulonephritis. Suppression of lymphocyte proliferation observed in the presence of HBsAg and HBsAg-IgG complexes was irreversible. However, the suppressive effect of HBeAg and HBeAg-IgG was abolished when these preparations were removed from the culture. Addition of exogenous interleukin-2/IL-2/reversed only the suppressive effect of HBeAg-IgG which was constantly present in the culture. The inhibition of lymphocyte proliferation correlated well with the decreased level of IL-2 activity in cultures with HBV-preparations. Experiments performed using ultracentrifugation indicated that HBV preparations, especially HBsAg and HBsAg-IgG, may bind to IL-2 and inactivate it in supernatants. The experiments indicate that HBV antigens, as well as other viral products, can inhibit lymphocyte proliferative response to the mitogen. Furthermore, we suggest that this inhibition may occur via suppression of IL-2 synthesis.

Antigen-Antibody Complex↗
PubMed1988

Cluster formation in PHA-stimulated mononuclear cells from peripheral blood: effects of colcemid and taxol.

Mononuclear cells from peripheral blood were incubated with phytohemagglutinin (PHA) for 24-72 hours. The cells formed dense cell clusters with firm cell-to-cell attachment and signs of cell communication, proliferation and differentiation. At the end of a 72-hour period of incubation, the test preparations were treated for 90 minutes with the classical microtubule antagonist Colcemid and the new microtubule antagonist taxol. Taxol produced approximately twice as many mitoses as Colcemid. Chromosomes in taxol-blocked mitoses appeared to be more contracted than chromosomes in Colcemid-blocked mitoses. It is suggested that one beneficial side effect of Colcemid preparation of chromosomes is stretching due to microtubule disassembly.

Alkaloids↗
PubMed1986

Manifestation of radiation injury of human lymphocytes using PHA mitogenic stimulation in different culture systems.

The proliferative response of human lymphocytes to PHA in vitro is affected by X-irradiation. Dose-related changes of mitogenic stimulation of irradiated lymphocytes were compared in two culture systems--cultivation of separated lymphocytes and cultivation of whole blood. In whole blood cultures, the proliferative activity of stimulated lymphocytes was markedly and reproducibly depressed by irradiation. The values of mitogenic response within a dose range from 0 to 2.5 Gy could be fitted with high correlation by an exponential curve. In a modified test where the mitogenic stimulus was given after 24 h delay, depression of the response was even more pronounced. Radiosensitivity of human lymphocytes as determined by means of mitogenic stimulation in whole blood cultures appears to be a characteristic individual feature. The mean D37 value of the radiation-induced depression of mitogenic response in a group of 20 healthy donors was 2.5 Gy in the standard test and 2.0 Gy in the test with a delayed mitogenic stimulus. In contrast, the data obtained from separated lymphocyte cultures were characterized by a high degree of the test-to-test variability and by much lower radiosensitivity. The possible mechanisms of these distinctive manifestations of the same primary radiation injury are discussed.

Adult↗
PubMedDate not supplied

[Antinuclear antibodies and PHA response in rheumatoid arthritis].

We have studied the in vitro PHA response of two groups of rheumatoid arthritis patients differing only in the presence or absence of antinuclear antibodies. The response was depressed in positive patients and normal in negative patients. Differences in peripheral blood mononuclear cell sub-populations or lymphocytotoxic antibodies do not seem to explain this observation. Simple antinuclear antibody screening could serve as a simple method to identify a sub-group of immunodepressed rheumatoid patients as potential candidates for immunostimulating therapy.

Antibodies, Antinuclear↗
PubMed1977

Expression of Fc and complement receptors on T lymphocytes activated in vitro by phytohaemagglutinin (PHA).

In this work T-enriched lymphocyte populations (obtained from Ig-anti-Ig-Degalancoated columns) were studied for their surface markers, especially for Fc and complement receptors, before and after a pulse-PHA-stimulation. It has been demonstrated that activated T lymphocytes express on their surface both of these markers in high percentage. The hypothesis is discussed that B and T lymphocytes differ only with regard to the presence of surface immunoglobulins or the ability of forming spontaneous rosettes. On the contrary the other surface markers may probably be expressed when needed functionally by the cells.

Adult↗
PubMed1978

Subpopulations of T and B lymphocytes in peripheral blood and lymphocytes reactivity to non-specific mitogens (PHA, Con A, PWM) in in vitro cultures in patients suffering from in vitro cultures in patients suffering from glomerulonephritis.

Studies were performed on 79 subjects, out of which 32 belonged to the control group and 47 suffered from glomerulonephritis. The number of T and B lymphocytes in peripheral blood was determined using the technique of E, EA and EAC-rosette tests. Also, the lymphocyte blast response to non-specific mitogens (PHA, Con A, PWM) was established in vitro. Patients suffering from acute proliferative glomerulonephritis, as compared to the control group, displayed a statistically significant increase of lymphocytes with the receptor for complement (EAC-rosettes). Their reactivity to all three mitogens did not differ from the values obtained in the control group. In patients suffering from chronic glomerulonephritis (proliferative, membranous-proliferative, membranous), shiftings in the contents of the peripheral blood lymphocytes pools were of opposite directions, i.e., statistically significant in comparison with the control group. Also an increase in the absolute number of T lymphocytes (E-rosettes) was observed. Generally speaking, the values of blast transformations after mitogen stimulations were smaller in patients suffering from chronic than in those suffering from acute glomerulonephritis. In 1/3 of them, the decrease of blast response to one of the three mitogens was detected. The decrease exceeded the lower limit of values of healthy subjects, and most often, it was connected with Con A stimulation.

B-Lymphocytes↗
PubMedDate not supplied

[Genetic regulation of T-lymphocyte responsiveness to PHA is independent of culture conditions (author's transl)].

A maximal interline separation has been obtained after 10 consecutive generations of selective breeding for the character "quantitative in vitro response of lymph node lymphocytes to the mitogenic effect of phytohaemagglutinin". At the selection limit the difference between high and low responder lines was about 20-fold. A similar interline separation has been demonstrated for the T-mitogen effect of concanavalin A. The identical response to PPD (purified protein derivative of tuberculin), a B mitogen, proved that the genetic selection has only modified the potentialities of T lymphocytes. During the selective breeding, responsiveness to PHA stimulation has been always measured under identical culture conditions. To demonstrate that the interline difference in responsiveness was due essentially to genetic factors independent of environmental effects, a systematic study of various culture conditions has been undertaken. The optimal stimulation was found after two days of culture for high line cells and after three days for low line cells. The difference between maximal responses was only slightly lower than that obtained after a two-day culture as used for the selection test. Increase in cell concentrations produced higher thymidine incorporation. In the two lines, a linear correlation was established between the cell concentration and the response produced. The maximal response given by the highest number of low line lymphocytes was equivalent to that given by a number, 11-fold smaller, of high line cells. Within certain limits, changes in the amount of tritiated thymidine added to the culture did not affect the interline separation. With a thymidine of high specific activity, a sub-evaluation of uptake by high line cells decreased the interline difference. Results in mixed culture of lymph node cells from high and low lines indicated that the low response was not due to the release of inhibiting factors or to the presence of suppressive cells in low responder mice. In conclusion, separation of these two lines was due to genetic factors acting independently of the cell culture conditions.

Animals↗
PubMed1987

TG and TnonG lymphocyte involvement in the proliferative response to PHA. I. Reactivity and regulatory functions of TG and TnonG subsets in the proliferative response of T lymphocytes.

Both TG and TnonG subpopulations from human peripheral blood were found to secrete helper and suppressor factors for the PHA-induced T cell proliferative response. The TnonG subpopulation contained cells which were both able to secrete helper factor and to respond by proliferation, whereas in the TG subpopulation cells with a proliferative potential could not be conclusively demonstrated. Suppressor and helper activities in TG and TnonG culture supernatants displayed a different time kinetics and were influenced by the dose of mitogen in test cultures.

Cells, Cultured↗
PubMed1986

Monitoring of effects of cis-diamminedichloroplatinum (II). Part III. Effect of platinum complexes on PHA-stimulated proliferation of human peripheral blood mononuclear cells in vitro.

The effect of the platinum complexes cis-DDP and CBDCA on the functions of human peripheral blood mononuclear cells (PBMC)--viability, proliferating activity after polyclonal stimulation with phytohemagglutinin is followed in an in vitro study. Both the platinum complexes (at concentrations 10(-5) up to 10(-9) mol/l) inhibit significantly the proliferating activity of PBMC without affecting its viability, i.e. integrity and permeability of the cell membrane structures. As to effectivity, cis-DDP has shown itself a more effective inhibitor of cellular proliferation than CBDCA of which 10-100 times higher concentrations are required to achieve the same inhibitory effect in dependence on the temporal relation to the application of phytohemagglutinin. The highest inhibitory effect is noted when cis-DDP is applied either simultaneously with, or 48 h after PHA, i.e. at the stage of maximum proliferating activity. The results bring support to the assumed mechanism of action of the above platinum complexes--intervention into DNA synthesis. Since the test of blastic transformation of PBMC is held to be an image primarily of the function of T lymphocytes, it may be inferred that platinum cytostatics can affect cell-mediated immunity also in patients.

Adult↗