Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PHA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources
PubMed1986

The relationship between metal ion content and mitogenicity of PHA-L4 isolectin as determined by agarose electrophoresis.

The lectin (PHA) from Phaseolus vulgaris is a tetrameric metalloprotein which exists as 5 different isolectins. An agarose electrophoretic assay is described that can distinguish between metallized and demetallized PHA. The assay has been employed for the analysis of 5 different preparations of the isolectin PHA-L4, and the preparations have subsequently been tested for their ability to induce lymphocyte transformation. A reverse correlation was found between the relative amount of irreversibly demetallized isolectin, as determined by agarose electrophoresis and the mitogenic activity of the preparation. The degree of irreversible demetallization seemed to be dependent on the preparation method used. One method gave 25% and another 100% demetallization of the isolectins. The assay was found to be a rapid and simple way to test the relative amount of mitogenically active lectin present in a preparation.

Calcium↗
PubMed1987

Determination of the T3-3A1 antigen in PHA-induced human T-cells by standardized cell-ELISA.

The treatment of mononuclear leukocytes (MNL) with lectins induces marked changes in the cell's morphology, physiology and the composition of the cell surface. We used an immunoassay to monitor the PHA-induced expression of the T-lymphocyte-specific antigen T3-3A1 in fixed MNL with a monoclonal antibody (MoAb) specific for this antigen. This assay permits the detection and quantitation of the T3-3A1 antigen in a few thousand cells without the use of a FACS. The test was calibrated with isolated plasma membranes and, combined with a total protein determination, the relative content of T3-3A1 antigen in each sample could be calculated. Maximal T3-3A1 synthesis required a 10-fold lower concentration of PHA than was necessary for optimal DNA synthesis. The test may be used to screen for PHA stimulation.

Antibodies, Monoclonal↗
PubMedDate not supplied

The PHA-induced calcium signal in lymphocytes is altered after blockade of K(+)-channels in Alzheimer's disease.

Several lines of evidence indicate that alterations in intracellular calcium homeostasis with sustained elevation of free calcium ions ([Ca2+]i) might be important in the pathophysiology of Alzheimer's disease (AD). Recent studies with peripheral blood-cells have demonstrated that investigation of regulatory mechanisms in calcium homeostasis might be more promising than determining only resting or stimulated [Ca2+]i values. With respect to the importance of potassium (K+)-channels in intracellular calcium regulation we have investigated whether a potassium channel dysfunction, already demonstrated for AD fibroblasts (Etcheberrigaray et al., 1993, Proceedings of National Academy of Sciences USA, 90, 8209-8213), could be observed in circulating lymphocytes as well. Thus, we studied the influence of the K(+)-channel inhibitor tetraethylammonium (TEA) on basal and PHA-stimulated [Ca2+]i in lymphocytes from AD (n = 20), non-demented depressed patients (n = 15) and age-related healthy controls (n = 23). Preincubation of lymphocytes with 100 mmol/l TEA resulted in a 45.5 +/- 8.8% inhibition (mean +/- SD) of the PHA induced rise in [Ca2+]i in healthy controls and 37.3 +/- 11.3% inhibition in depressed patients. With lymphocytes of AD patients, this effect of TEA was significantly reduced (23.2 +/- 8.8%, p < .001). If the individual data are considered there was almost no overlap between AD patients and healthy controls, since only three (15%) AD patients responded to TEA with > 30% inhibition, but only one of the controls (5%) responded with < 30% inhibition. Besides the reduced signal-inhibition by blockade of K(+)-channels we have observed a delayed response of AD lymphocytes in [Ca2+]i rise after PHA stimulation, suggesting that functional plasticity of the cells is reduced. Although the significance and molecular basis of this K(+)-channel dysfunction are not yet determined, the presented data are of great significance because of diagnostic reasons and especially because this model thus offers a possibility to investigate functional cellular alterations in vivo.

Adult↗
PubMed1983

T-cell subsets in human lymphocytes maintained in IL-2 medium after PHA or mixed lymphocyte reaction activation.

The culture of human T lymphocytes in interleukin-2 (IL-2) containing growth factor medium results in a significant shift in the T-lymphocytes subsets isolated from such cultures at weekly intervals. If normal peripheral blood mononuclear cells are stimulated with phytohemagglutinin (PHA) or in a mixed lymphocyte reaction (MLR), the resulting T lymphoblasts can be propagated in growth factor medium. Staining of the cultured cells with monoclonal antibodies was evaluated by indirect immunofluorescence on a laser-activated flow cytometer (Ortho Spectrum III). The antibodies used were: OKT3 (mature T lymphocytes), OKT4 (helper/inducer T lymphocytes), OKT8 (cytotoxic/suppressor T lymphocytes, OKT10 (immature and "activated" lymphocytes), OKT11a (cells which rosette with sheep erythrocytes), and OKIa-I (HLA-DR constant region). Both PHA and MLR activation resulted in initial preservation of the OKT4+ subset predominance over OKT8+ T lymphocytes noted on normal circulating blood lymphocytes. However, during culture in T-cell growth factor medium, there was a progressive increase in the percentage of OKT8+ cells, and a concomitant decrease in OKT4+ lymphoblasts. The increase in OKT8+ cells in the MLR-stimulated cultures was paralleled by an increase in specific cell-mediated cytotoxicity against the stimulating lymphocyte population. In addition to the shift in T-lymphocyte subset, there was virtual 100% staining with OKT3 and OKT11a, indicating the T-cell nature of the proliferating cells. OKT10 which was present on a small subset of fresh blood lymphocytes appeared rapidly in stimulated cultures, and was retained on virtually all lymphoblasts of either OKT4+ or OKT8+ subset. OKIa-1 cells increased slowly in PHA-stimulated cultures. HLA-DR+ T cells were detected earlier in MLR cultures. The activation of T lymphocytes results in a significant increase in the number of molecules of OKT11a bound per cell, in concert with the increased avidity of T lymphoblasts for sheep erythrocytes. The significant change in the phenotype and function of lymphoblasts isolated from long-term cultures demonstrates the importance of monitoring cultures, and the potential hazards in equating a cultured cell population with a freshly isolated one.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1986

Does normal lymphocyte DNA synthesis in response to PHA exclude cell-mediated immunodepression?

PHA stimulation assay was the first in vitro method for evaluating the T-cell function, and this T-cell proliferative response has been routinely used to discriminate between normal subjects and patients with deficiency in cell-mediated immunity. However, [3H]thymidine incorporation into lymphocyte DNA can be studied by using additional in vitro assay methods since they measure different lymphocyte activation pathways. In the present study we selected three different tests to investigate the reliability of this single approach: PHA induced lymphocyte DNA synthesis; T lymphocyte DNA synthesis to anti-T3 monoclonal antibody (OKT3); autologous mixed lymphocyte reaction (AMLR). In addition, IL-2 receptor expression on the membrane of T-cell stimulated in AMLR both with PHA and anti-T3 was evaluated. This study was performed in various groups of subjects: normal young controls, aged healthy individuals, and patients with Alzheimer's disease (AD), Retinitis Pigmentosa (RP), and with cell-mediated immunodeficiency and clinical evidence of recurrent viral infections (ID). The data reported herein show heterogeneity of results in each group studied and demonstrate the necessity of employing more than one laboratory test for the routine evaluation of T-cell-mediated immunity.

Alzheimer Disease↗
PubMed1982

Chronic T-cell leukaemias. III. T-colonies, PHA response and correlation with membrane phenotype.

The functional capacity of T lymphocytes from 28 cases of chronic T-cell leukaemia--T-CLL, T-PLL, T-LCL and Sézary syndrome--was evaluated in a T-colony forming system and in a PHA response assay. Reduced or absent T-colony growth was observed in 23 cases (82%) while in five the growth was normal. Although a good correlation was generally observed between colony formation and PHA transformation, in a few cases a low PHA response was accompanied by moderate colony growth and vice versa. Characterization of the leukaemic T lymphocytes using monoclonal antibodies (OKT series) indicates that cases with a helper/inducer phenotype (OKT4+) showed moderately reduced or near-normal T-colony numbers, whilst cases with a suppressor/cytotoxic phenotype (OKT8+)--confined to T-CLL in this study--had a very low or absent colony growth. The functional abnormalities reported here suggest that neoplastic T-cells with a helper/inducer phenotype show a low proliferative response in the assay systems used, although expressing mature T-cell characteristics. The low growth observed in T-CLL confirms that cells with a suppressor/cytotoxic phenotype form few T-cell colonies.

Cell Division↗
PubMed1991

The proliferative activity of B-chronic lymphocytic leukaemia lymphocytes prior to and after stimulation with TPA and PHA.

The proliferative activity of B-CLL lymphocytes from 10 patients was investigated both prior to and after stimulation with TPA and PHA. The analysis of cell cycle-associated features such as BrdU incorporation and the expression of the nuclear proliferation-associated antigen, Ki-67, together with the phenotypic profile of the cells, was performed using double colour immunofluorescent methods. The unstimulated B-CLL cells represented a homogeneous population with the same cell cycle position (G0) as resting peripheral blood lymphocytes. After TPA stimulation 22.7% of the lymphocytes were found in G1, 9.4% in S + G2/M and 13.4% in post-M. PHA stimulation induced a greater proportion of cells in G1, i.e. 35% and 17.8% into S + G2/M and 13.4% into post-M. Double colour immunofluorescence was able to demonstrate that in TPA cultures the majority of the stimulated lymphocytes originated from the malignant clone. Evidence of B-CLL lymphocyte proliferation using double colour labelling with BrdU and Ig kappa and/or Ig lambda showed that a small minority of B-CLL lymphocytes were stimulated into S + G2/M phases of the cell cycle. PHA was also capable of inducing a small proportion of B-CLL cells into mitosis although this proportion of cells was smaller compared to the TPA-stimulated lymphocytes.

Aged↗
PubMed1988

Anterograde and retrograde axonal transport of Phaseolus vulgaris leucoagglutinin (PHA-L) from the globus pallidus to the striatum of the rat.

Iontophoretic administration of PHA-L into the globus pallidus of rats resulted in the labeling of neuronal perikarya in the striatum as well as axons and terminals in the striatum, entopeduncular nucleus, subthalamus and substantia nigra. The labeled striatal perikarya were densely stained in Golgi fashion with virtually complete filling of the dendrites and spines. It is concluded that the striatal cells were filled by the retrograde transport of PHA-L and represent either striatopallidal cells, or striatonigral cells whose axons were interrupted as they passed through the injection site. The anterogradely labeled axon terminals in the striatum were observed in close apposition to the dendrites of the retrogradely labeled neurons suggesting the existence of synaptic contacts between the two groups of cells. This study demonstrates that PHA-L can be transported retrogradely as well as anterogradely following iontophoretic injections.

Animals↗
PubMedDate not supplied

Intra-axonal Neurobiotin injection rapidly stains the long-range projections of identified trigeminal primary afferents in vivo: comparisons with HRP and PHA-L.

Currently available methods for studying the morphology of physiologically characterized primary afferents are limited by difficulties inherent in impaling thin fibers and by the limited distances over which conventional tracers move during the course of a recording session. We have encountered an alternative method that overcomes these limitations. Neurobiotin (NB; Vector) injections into rat trigeminal (V) primary afferents in the brain stem or V ganglion provided rapid, long-range staining with recording and electrophoretic parameters that are commonly used to eject horseradish peroxidase (HRP) or Phaseolus vulgaris leucoagglutinin (PHA-L). When NB was injected into brain stem fibers responsive to vibrissal deflection with A-beta conduction velocities, collaterals were darkly stained in each of the 4 V subnuclei, as well as the cervical dorsal horn. Labeled fibers were also seen in the V root and peripherally in the infra-orbital nerve for a distance up to 15 mm from the injection site (30 mm total). Cell bodies in the ganglion were never labeled. When NB was injected into V ganglion cells with low- or high-threshold receptive fields and A-beta or A-delta conduction velocities, parent axons were stained in the V spinal tract to the level of the obex, and collaterals were visible in each of the 4 V subnuclei. Such long-range staining occurred within 4 h of tracer injection. HRP never stained brain stem fibers following ganglion cell injections and, when injected centrally with the same survival intervals used with NB, dark staining was limited to within 4 mm of the injection site. Unlike NB or HRP, PHA-L injections rarely produced useful data, either because of the high mortality accompanying attempts to achieve a 1-2 week survival period or because injected neurons were not recovered. Due to its rapid and robust transport, NB is a more convenient and reliable tracer than PHA-L for producing long-range staining of the projections of identified ganglion cells. Intracellular injection of NB also produces rapid Golgi-like staining of fibers over much greater distances than HRP under equivalent staining parameters.

Afferent Pathways↗
PubMed1991

Syncytiotrophoblast plasma membrane inhibits membrane expression of activation markers on PHA-stimulated human lymphocytes.

Studies have been carried out on the effects of full-term human syncytiotrophoblast plasma membrane (STPM) preparations on the membrane expression of the lymphocyte activation markers HLA-DR, IL-2R, TfR and CD69 during PHA-induced lymphoproliferation. STPM considerably decreases the expression of both late (HLA-DR) and early (IL-2R, TfR, CD69) activation markers at doses which inhibit PHA-induced lymphoproliferation. These results favour the hypothesis that STPM inhibits a very early phase of PHA-induced lymphocyte activation.

Antigens, CD↗
PubMed1984

Development of optimal conditions for the stimulation of chicken peripheral blood lymphocytes by phytohaemagglutinin (PHA) in the microculture system.

A variety of parameters influencing phytohaemagglutinin (PHA) stimulation assays of lymphocytes obtained from chicken peripheral blood have been studied. The parameters examined were PHA preparation and dilution, source and quantity of serum, cell concentration, culture medium, incubation temperature, length of the incubation period, cell separation procedure and individual influence of the blood donors. Optimal stimulation results were obtained using the following conditions: PHA-M in a dilution of 1:15, fetal calf serum (FCS) in a concentration of 4%-10%, a cell concentration of 4 X 10(6) - 1.5 X 10(7) cells/ml, RPMI 1640 Medium or McCoy's 5A Medium, an incubation period of 48 h - 72 h at a temperature of 39 degrees C, and low-speed centrifugation of heparinized blood for lymphocyte collection. The findings of the present study are discussed in the context of results described in the literature.

Animals↗
PubMed1985

The role of monocytes in the suppression of PHA-induced proliferation and IL 2 production of human mononuclear cells by 1,25-dihydroxyvitamin D3.

1,25-dihydroxyvitamin D3 [1,25(OH)2D3] inhibited phytohemagglutinin (PHA)-induced proliferation of human blood mononuclear cells (MNC) at concentrations of 10(-11) M or more. Interleukin 2 (IL 2) production of T cells activated with PHA was also inhibited by 1,25(OH)2D3. Furthermore, 1,25(OH)2D3 suppressed interleukin 1 (IL 1) production of monocytes (Mo), and the agent-treated Mo were unable to promote IL 2 production of non-adherent cells (NAC). Thus, the reduction of proliferative response of MNC to PHA by 1,25(OH)2D3 appeared to have resulted from the inhibitory effects of the agent on both IL 2 and IL 1 production. From these data, 1,25(OH)2D3 appears to play an important role in the immunoregulatory system.

Calcitriol↗
PubMed1992

Intracellular expression of CD1 molecules on PHA-activated normal T lymphocytes.

In this study we have analyzed, using immunoperoxidase (IPx) and indirect immunofluorescence (IIF), the intracellular and cell surface expression of CD1 antigens on PHA activated human T cells. By IIF, CD1 isotypes were not detected on the surface of 3 days PHA activated cells. Conversely, CD1a, CD1b and CD1c molecules were found by IPx in the cytoplasm of normal activated cells from 13 different donors. Kinetic studies showed that, while CD25 was already observed 24 h after activation, all 3 isotypes of CD1 molecules started to be detected 48 h after PHA activation, with a peak expression at 72 h.

Antigens, CD↗
PubMed1984

Indirect stimulation of B-cell proliferation in vitro by T cells, as evidenced by cytogenetic analysis of PHA-stimulated cell cultures of B-cell lymphomas.

In a retrospective study of non-Hodgkin's lymphomas, the 14q+ marker was found in at least one of the samples examined from 17 patients with B-cell lymphoproliferative diseases (LPD). In the PHA-stimulated cultures, the marker was found in each sample in 10%-100% of the cells. An indirect stimulation, as indicated by a 3H-thymidine incorporation and IG secretion, of normal B cells by a T-cell mitogen, such as PHA, has been recently documented. This phenomenon is confirmed by our chromosome analysis, which demonstrated characteristic chromosome changes in PHA-stimulated cultures of patients with B-cell malignancies and indicated that the phenomenon can be observed not only in normal B cells but also in malignant B cells.

B-Lymphocytes↗
PubMedDate not supplied

Elderly high NK responders are characterized by intensive proliferative response to PHA and Con A and optimal health status.

In this paper we verify a hypothesis emerging from recent immunogerontological studies assuming that an elevated level of NK activity in the elderly may be regarded as a factor compensating for a decreased reactivity of T cells. According to this assumption a high NK activity should be associated with a poor reactivity of T cells. In our study the mitogenic responses of lymphocytes of the elderly and the young high and low NK responders to phytohemagglutinin (PHA) and Concanavalin A (Con A) were measured. A high level of NK activity was not found, as would be expected from the hypothesis, to be associated with a poor reactivity to PHA and Con A. In contrast, the mitogenic response to PHA and Con A was intensive in both the young and old high NK responders while weak proliferative responses to T cell mitogens were characteristic of the young and old low NK responders. Thus, our results do not support the assumption of an association between a high NK activity and a low proliferative response to T cell mitogens in the elderly. We also found that both the elderly and the young high NK responders were characterized by an optimal health status.

Journal Article↗
PubMed1989

Efferent connections of the nucleus reuniens and the rhomboid nucleus in the rat: an anterograde PHA-L tracing study.

Direct projections from the nucleus reuniens (Re) and the rhomboid nucleus (Rh) in the midline of the thalamus were examined in the rat by utilizing anterograde axonal transport of Phaseolus vulgaris leukoagglutinin (PHA-L). The Re projected axon terminals densely to the anterior cingulate cortex, infralimbic area of the medial frontal cortex, agranular insular cortex, entorhinal cortex, and parasubiculum. Labeled terminals in these cerebral cortices were distributed mainly in layer I, except for the entorhinal cortex where labeled terminals were distributed in layers I-IV. On the other hand, labeled terminals of projection fibers from the Rh to the cerebral cortex were distributed in layers II-VI of the anterior cingulate cortex, frontal cortex, parietal cortex, and agranular insular cortex. In the nucleus accumbens, caudate putamen, and basolateral amygdaloid nucleus, labeled terminals from the Rh were more dense than those from the Re. In the hypothalamus, labeled terminals from the Re were more dense than those from the Rh. The septal nuclei and field CA1 of Ammon's horn received labeled axon terminals from the rostral portion of the Re, but not from the caudal portion of the Re or the Rh. The patterns of distribution of axon terminals from the Re and Rh were similar in other subcortical target regions. To confirm the PHA-L results, wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) was injected into two projection sites of PHA-L-labeled axons. After injection into the agranular insular cortex, WGA-HRP-labeled neurons were found in the Re, but only a few were present in the Rh. In contrast to this, after WGA-HRP injection into the nucleus accumbens, WGA-HRP-labeled neurons were found in the Rh, but only a few were seen in the Re.

Animals↗
PubMed1990

Cortical laminar distribution of rat thalamic ventrolateral fibers demonstrated by the PHA-L anterograde labeling method.

The cortical innervation pattern of rat thalamic ventrolateral (VL) fibers was investigated with the Phaseolus vulgaris-leukoagglutinin (PHA-L) anterograde labeling method. The PHA-L-labeled terminals were distributed in the sensorimotor cortex where the cerebello-cerebral (C-C) evoked responses were recognized. The labeled terminals were detected in all layers except layer VI. In the upper part of layer I, the most densely packed terminals were formed and moderately labeled terminals were seen in layers IV and V. Such a laminar distribution of PHA-L-labeled VL terminals is consistent with the profiles of the C-C responses according to laminar field potential analysis.

Animals↗
PubMed1992

Morphological features of cat thalamo-parietal projection fibers investigated by PHA-L immunohistochemistry and electron microscopy.

Thalamo-parietal fibers originating from the ventroanterior-ventrolateral (VA-VL) complex in the cat were labeled with Phaseolus vulgaris leucoagglutinin (PHA-L) and examined by light and electron microscopy. PHA-L (2.5% aqueous solution) was injected iontophoretically through micropipets with anodal current pulses into the VA-VL complex. PHA-L-labeled terminals were distributed in the lateral and the suprasylvian gyri in the superficial and deep cortical layers. In layer I, horizontal varicose fibers and terminals were conspicuous in the upper one-third and were widely distributed. In the deeper cortical layers (layers III-V), varicose fibers and terminals were detected in moderate numbers. Electron microscopic examination revealed that the labeled terminals formed asymmetrical synapses on the dendritic spines of spiny neurons. These morphological findings appeared to be consistent with our previous intracellular recordings in this cortex.

Animals↗