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 271 records · Page 15Linked to original sources
PubMed1975

[A micro-method for PHA-induced stimulation of human lymphocytes. I. Communication: Technical considerations (author's transl)].

A microculture system is described for PHA-induced stimulation of human peripheral lymphocytes. Following purification on Ficoll-Isopaque cells are incubated in microplates (Falcon 3040) for 66 hours in 5% CO2 using PHA-P (Difco) as a stimulant. DNA-synthesis is measured by labelling with 3H-thymidine (spec. act. 400 mCi/mmole) 16 hours prior to the end of the test. Using a multiple automatic sample harvester rapid evaluation is possible. Several variables were analyzed and optimal conditions defined for PHA- and cell-concentration, time dependence, thymidine dosage and buffer capacity of the medium. High variability and otherwise unexplained loss of lymphocyte stimulation in a population of "normal donors" are often due to acute viral infections, especially during the incubation period. On the other hand, source and concentration of serum are of equal importance since sera of healthy individuals differ greatly in their capacity to support PHA-induced stimulation of normal allogeneic lymphocytes. Using pooled or autologous serum we found the reproducibility of the technique to be good. Provided optimal conditions are employed the microtest system described herein should be ideal for in-vitro-analysis of inhibitory or stimulating factors in cancer patients' sera.

Adult↗
PubMed1977

Histological and histochemical pattern of phytohemagglutinin (PHA) skin test in patients with sarcoidosis.

Phytohemagglutinin (PHA) is a non-specific stimulant of blastogenic transformation and proliferation of T-lymphocytes in vitro. This material has been used for detection of a reduced lymphoblastic transformation in vitro and, as a skin test, for providing information in the evaluation of cellular immunodeficiency in man (BLAESE et al. 1973). As in sarcoidosis the immunological features are "depression of delayed-type hypersensitivity suggesting T-cell anergy and raised serum immunoglobulins suggesting B-cell overactivity", the authors used PHA skin test in comparison with patients with tuberculosis and M. Hodgkin. PHA positive reactions recorded at 72 hrs. were in 95% for sarcoidosis, 90% for tuberculosis and 5% for M. Hodgkin. But the histological and histochemical investigation of cutaneous biopsies demonstrated three significant differences at 72 hrs. in untreated patients with sarcoidosis compared to the material of tuberculosis patients: formation of lymphatic pseudo-follicles, an increased number of arteriovenous anastomoses and appearance of C-mucopolysaccharide (a histochemical marker of connective tissue in sarcoidosis). There were in sarcoidosis, unlike tuberculosis, blast cells, plasmocytes and a number of lymphocytes at 72 hrs. It is difficult for the authors to explain the different behaviour of the PHA skin test in sarcoidosis and tuberculosis. The appearance of the C-mucopolysaccharide might be a result of the raised serum level of IgM in patients with sarcoidosis.

Glycosaminoglycans↗
PubMed1992

Cell line specific abnormalities in expression of PNA, SBA and L-PHA binding sites by carcinogen induced rat urothelial carcinomas.

Bladder tumor cell lines derived from male F344 rats treated with N-buthyl N-(4-hydroxybuthyl) nitrosamine (BBN) or N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) have been established in vitro and characterized with respect to histology, karyotype, myc and c-Ha-ras oncogene expression or mutation, anchorage-independent growth and tumorigenicity in nude mice. This unique model system comprising 13 cell populations was employed to study common events during development of carcinogen-induced urothelial neoplasia. Differential expression of malignant phenotypes by these cell lines prompted us to examine their expression of carbohydrate structures binding peanut agglutinin (PNA), soy bean agglutinin (SBA) or leukoagglutinin (L-PHA), which are known indicators of tumor progression in rodents and humans. In the present study we analyzed the patterns of glycoproteins reactive with PNA and L-PHA by Western blotting. We also estimated quantitative differences in lectin binding to surfaces of normal rat urothelium and tumor cell lines by flow cytometry. The patterns of PNA or L-PHA reactive glycoproteins expressed by tumor cells were different from that of normal urothelium in culture. They were also different amongst the tumor cells. A unique non-sialylated, PNA binding glycoprotein (117 kD) was seen in the case of the highly tumorigenic F5 cell line and absent in normal urothelium as well as in other tumor cell lines. Normal cells did not express glycoprotein 60 kD binding PNA (only after desialylation), which was found in lysates of some but not all transformed cell lines. A very high molecular weight (much greater than 200), perhaps mucin-like sialoglycoprotein was found in normal urothelium but not in most of the tumor cell lines. Four major L-PHA reactive bands (greater than 200, 190, 100, 80 kD approximately) were found in normal urothelium. Some of those bands were overexpressed or missing in materials isolated from different tumor cell populations. Total cell surface binding of SBA and PNA by different tumor cell lines was very heterogenous (167-2% that of normal urothelium). No simple correlation between expression of the lectin binding glycoconjugates by urothelial carcinoma cells and other known functional, phenotypic or genetic alterations was found. We were also unable to demonstrate carcinogen-specific changes in expression of lectin binding to these tumor cell lines. Thus we conclude that lectin binding patterns are cell line specific. This may reflect distinct pathways of progression of individual cell lines. The potential sources of phenotypic variability between the cell lines were discussed.

Animals↗
PubMed1990

Potential role of PHA in producing human monoclonal thyroid autoantibodies of different subclasses.

A human monoclonal autoantibody to thyroglobulin (Tg) of subclass IgG2 was developed by fusing a mouse myeloma with Tg antibody secreting Epstein-Barr virus (EBV)-infected B lymphocytes from a Hashimoto patient. Subsequent studies showed that EBV-infected B lymphocytes from this patient synthesized IgG2 Tg antibody while unfractionated blood lymphocytes cultured with pokeweed mitogen secreted IgG1, IgG2, and IgG4 Tg antibodies in amounts proportional to those present in the patient's serum. To investigate this discrepancy further, we cultured EBV-infected lymphocytes from blood, lymph nodes, and thyroid tissue in medium alone and with increasing concentrations of PHA. In individuals with thyroid autoantibodies predominantly of subclass IgG1, PHA enhanced the levels of total Tg antibody synthesis without affecting the IgG subclass distribution. However, in patients with serum autoantibodies of subclasses IgG1, 2, and 4, the increased levels of total Tg antibody synthesis were associated with increased amounts of thyroid autoantibodies of all of these subclasses; in some instances IgG1 and IgG4 autoantibodies were only synthesized in cultures containing PHA. These observations suggest that addition of the T-cell mitogen PHA to cultures of EBV-infected lymphocytes may ensure activation of B-cell precursors committed to synthesizing the IgG subclasses characteristic of serum antibody in the lymphocyte donor. Since Tg antibodies of subclasses IgG2 and IgG4 recognize different epitopes on Tg, the ability to produce human monoclonal antibodies of different IgG subclasses may simultaneously ensure the development of antibodies to different epitopes on the same antigen.

Animals↗
PubMedDate not supplied

The in situ detectability of the neuroanatomical tracer Phaseolus vulgaris-leucoagglutinin (PHA-L).

We determined the in situ detectability of the neuroanatomical tracer Phaseolus vulgaris-leucoagglutinin (PHA-L). The tracer was bilaterally injected in the nucleus accumbens of the ventral striatum of young adult rats. After post-injection survival periods ranging from 4.5 to 16 weeks, sections of the brain were subjected to immunocytochemical detection of the transported PHA-L. We examined the labelled neurons in the injection sites, the labelled local and efferent fibres, and the labelled terminal structures in the ventral pallidum. Up to 4.5 weeks after the injection, the PHA-L-labelled neurons in the injection site were completely stained and displayed dendrites with numerous spines. There was also good visualization of local axonal plexuses and of the efferent fibres and their varicosities along the trajectories to and in the termination areas. Six and a half weeks after the injection, the fibres coursing from the injection site to the termination area were difficult to visualize. By contrast, the injection site contained labelled cell bodies, dendrites with few spines, weakly stained fibres, and punctate labelling. In the termination areas there was a clear, punctate terminal labelling in addition to weak fibre labelling. Between 8 and 10 weeks after the injection, labelled neurons in the injection site could be visualized as well as a cloud of punctate staining in the termination area, but labelled fibres and dentritic spines were not observed. Eleven weeks after the injection, label was no longer demonstrable in terminals. After survival periods of 13 weeks and longer, the only labelled structures were weakly PHA-L-immunoreactive perikarya at the injection site, surrounded by punctate labelling.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Differential sensitivity to cAMP among human cord and maternal/adult peripheral lymphocytes discloses differences between PHA- and OKT3-induced activation pathways.

Previous studies have demonstrated that human cord blood lymphocytes are resistant to the anti-proliferative action of prostaglandin E2 (PGE2) in phytohaemagglutinin (PHA)-induced mitogenesis, whereas the same cells activated by OKT3 are at least as sensitive to PGE2 as the corresponding cells from their mothers or other adults. In the present investigation it was found that: (i) PHA-induced proliferation of cord peripheral blood mononuclear leucocytes (PBML) is less sensitive to inhibition by forskolin--a direct activator of adenylate cyclase (AC)--and dibutyryl cAMP--a permeant cAMP analogue--than the proliferation of the corresponding maternal cells; (ii) OKT3-induced proliferation of cord as well as maternal PBML is highly sensitive to inhibition by forskolin and dibutyryl cAMP; (iii) cord PBML show an overall lower rate of AC activity compared with maternal PBML, in response to PGE2 and other autacoids as well as to receptor-independent stimulation; (iv) cord PBML also display a significantly lower rate of degradation of cAMP through cAMP-phosphodiesterase compared with maternal cells; (v) unbroken cord and maternal PBML show comparable rates of cAMP accumulation after stimulation with PGE2. The results suggest a lower sensitivity to the effect of cAMP in cord compared with maternal/adult lymphocytes in PHA-induced proliferation. Moreover, the data illustrate differences between PHA- and OKT3-mediated activation pathways, as well as differences in cell regulation mechanisms between cord and maternal PBML.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1989

Effect of Pseudomonas aeruginosa exotoxin a on PHA-induced lymphocyte proliferation.

P. aeruginosa Exotoxin A induced a dose dependent suppression of PHA-stimulated human lymphocyte proliferation. The suppressor effect was not reversed by interleukin 2 (IL-2) added to the culture medium. Expression of IL-2 receptors (IL-2R) on PHA-blasts a well as their ability for IL-2 binding were decreased by Exotoxin A. Kinetic studies of IL-2 production showed that IL-2 activity was still present in cultures of lymphocytes activated for 72 hours with PHA and Exotoxin A. In contrast, supernatants of lymphocyte cultures activated with PHA and Exotoxin A for 18 hours had low activity of IL-2. Hence, Exotoxin A probably could decrease the utilization of IL-2 due to either inhibition of IL-2R expression or suppression of their ability for IL-2 binding.

ADP Ribose Transferases↗
PubMed1977

The effect of adherent and phagocytic cells on human lymphocyte PHA responsiveness.

The effect of small numbers of adherent and phagocytic cells on the human peripheral blood lymphocyte response to PHA was examined by depleting these cells from lymphocyte preparations. Lymphocyte preparations obtained by centrifugation on Ficoll--Triosil, which contained on average 85% lymphocytes, responded well to PHA. Depletion of cells adhering to nylon fibre, giving a population containing on average 95% lymphocytes, resulted in a considerably reduced response. Depletion of cells that adhered to plastic or ingested iron powder to give populations containing on average 90% lymphocytes, also reduced the PHA response, but to a lesser extent. Reduction in PHA responsiveness correlated with increasing lymphocyte purity. The responsiveness of nylon-column-filtered cells could be restored by adding a small number of cells from a monocyte-rich population.

B-Lymphocytes↗
PubMed1986

Effect of PHA-activated T cells on B-cell differentiation.

Recent studies indicate that human T cells expressing the T4 determinant are comprised of functionally distinct subsets. We investigated if activation of OKT4+ cells with the mitogen PHA affected their ability to regulate the proliferation and polyclonal differentiation of autologous B cells. OKT4+ cells were preactivated with PHA and then cocultured with autologous B cells in the presence or absence of PWM. B-cell proliferation and differentiation to immunoglobulin-secreting cells (IgSC) were assessed by [3H]thymidine incorporation and reverse haemolytic plaque assay, respectively. In the absence of PWM, the PHA-activated OKT4+ cells demonstrated radioresistant help and radiosensitive suppression of IgSC responses. Addition of PWM to cocultures of irradiated PHA preactivated OKT4 cells and autologous B cells resulted in further suppression of IgSC responses, suggesting that PWM activated yet another suppression mechanism. Addition of PWM caused diminished B-cell proliferation as well. These data demonstrate functional heterogeneity within the OKT4 subset, and suggest that the particular immunoregulatory activity displayed is influenced by the state and mode of activation of these cells.

Antibodies, Monoclonal↗
PubMed1987

Reactivity of B leukemic lymphocytes of patients with chronic lymphocytic leukemia to PWM and PHA.

The ability of leukemic B lymphocytes to proliferate after in vitro stimulation with PWM and PHA was studied in 15 patients with chronic lymphocytic leukemia. Peripheral blood lymphocytes of five healthy subjects as well as purified normal B lymphocytes were used as controls. Leukemic lymphocytes of all donors expressed the same membrane phenotype, M receptor, and B7 and Ia antigens. The lymphocyte populations investigated were not completely free from myelomonocytic cells and contained small numbers of T lymphocytes. DNA synthesis was determined on days 3, 5, and 7 of culture by measuring the incorporation of tritiated thymidine. PWM-induced proliferation of leukemic B lymphocytes of nine patients was within normal limits, while the response of leukemic cells of six patients was very low. On the other hand, all CLL donors responded very well to PHA. Moreover, the response of leukemic B lymphocytes was significantly higher than the response of normal B cells. It was concluded that leukemic B lymphocytes of CLL patients are capable of proliferation after stimulation with PWM and PHA. The mechanisms underlying these responses to PWM and PHA are likely to be different.

B-Lymphocytes↗
PubMed1986

PHA responsiveness and adherent cell-lymphocyte interactions in patients with advanced malignant tumors of the ovary prior to treatment and during chemotherapy.

DNA synthesis in cultures of PHA-stimulated blood mononuclear cells from patients with advanced malignant tumors of the ovary before treatment was significantly reduced and responses of lymphocytes alone were, on an average, 40% lower than in control subjects. Adherent cells were found to suppress the PHA response of autologous lymphocytes from 6/12 patients before treatment, 4/18 patients during chemotherapy and only in 2/19 control subjects. The net effects of adherent cell-lymphocyte interactions in autogeneic vs. allogeneic combinations were frequently discordant, which suggests shifts in lymphocyte subpopulations responsive, respectively, to suppressor- and helper-type mediators released by monocytes in patients. PHA responses of mononuclear blood cells from patients after the 1st and 2nd round of chemotherapy were usually higher than the mean in untreated patients, but declined rapidly after subsequent rounds of cytostatic drug treatment and were deeply impaired in a few cured patients examined many months after therapy. Previous radiotherapy appeared to have little effect on the magnitude and patterns of changes of blood mononuclear response to PHA during subsequent chemotherapy.

Adult↗
PubMed1977

Structure and biological functions of human IgD. XII. Anti-IgD enhancement of PHA responsiveness in patients with chronic lymphocytic leukaemia.

Specifically purifed anti-human delta stimulated the in vitro incorporation of [3H]thymidine by human peripheral lymphocytes from patients with chronic lymphocytic leukaemia (CLL). The peak response varied between individuals; those with 5--52% IgD-bearing lymphocytes exhibited maximum stimulation at 3 days, whereas a patient with only 1% IgD-bearing cells showed optimal activation at 6 days. In agreement with others, our data indicated that, in most instances, lymphocytes from patients with CLL respond poorly to PHA. One of the most important findings in this study is the enhancement of PHA responsiveness by anti-delta. Lymphocytes that exhibited reduced responsiveness to PHA alone, when pre-treated with anti-delta, showed transformation greater than the sum of the anti-delta plus PHA responses.

Aged↗
PubMed1982

Nonspecific suppressor cells in rheumatoid arthritis. Con A and PHA induced suppressor cell activity.

Suppression of the blastogenic response by autologous cells precultured with Concanavalin A (Con A) or Phytohemagglutinin (PHA) was studied in an in vitro system. The mean mitogen response of cells from normal individuals and from patients with Rheumatoid Arthritis (RA) in isologous plasma was similar. In isologous plasma there was no significant difference between the activity of Con A suppressor cells of normals and those of RA. Incubation of the cells in RA plasma abrogated the suppression in both normals and RA patients. In isologous plasma PHA suppressor cells were also induced in both groups, the levels being lower in the normals than in the RA group. PHA suppressor cell activity against PWM induced blastogenesis could not be engendered in normals. RA plasma abrogated PHA suppressor cell activity, especially in the RA group. The abrogating activity of RA plasma was heat stable, nondialysable and could be correlated with the presence of anti-lymphocyte antibodies in the RA plasma.

Arthritis, Rheumatoid↗
PubMed1984

Tumour-induced suppressor macrophages in rats: differences in their suppressive effects on the Con A and PHA responses.

Spleen cells obtained from ACI rats bearing a syngeneic hepatoma (9098) (TBR spleen cells) showed a strongly depressed mitogen responses to concanavalin A (Con A) and to phytohaemagglutinin-P (PHA) at various concentrations of the tested mitogens. The activity of suppressor cells in TBR spleens was demonstrated in mixtures with normal spleen cells where a marked depression of the mitogen response was observed. The properties of tumour-induced suppressor cells were adherent to plastic or nylon wool, phagocytic, and radioresistant (maybe macrophages). The Con A response of TBR spleen cells was more completely restored than was the PHA response after the removal of adherent or phagocytic cells. The suppression when TBR spleen cells (2,000 rad) were added to normal spleen cells at 0, 24, and 45 h after culture initiation was greater in the PHA response than in the Con A response. The PHA assay appeared to be more sensitive method than the Con A assay for the detection of suppressor cell activity in tumour bearing rats.

Animals↗
PubMed1984

[Quantification of lectin receptors on B, T, T-gamma, and T-mu lymphocytes. II. PHA, SBA, Dolichos biflorus, and Tetragonolobus purpureus].

Plasma membranes composition and structure of B, T, T gamma and T mu lymphocytes from peripheral blood have been studied using four 125I-labelled lectins. The results showed that B lymphocytes have a greater number of receptors for SBA and Dolichos biflorus lectins than T lymphocytes, whilst the opposite was observed for PHA-lectin. However, no significant differences between the two lymphocyte populations were found regarding the receptors for Tetragonolobus purpureus lectin. Among T lymphocyte subpopulations, SBA, Dolichos biflorus and tetragonolobus purpureus lectins appeared to have higher specificity for T gamma lymphocytes and PHA for T mu. PHA-lectin had greater affinity for B lymphocytes, while the rest showed higher affinity for T lymphocytes. The T gamma subpopulation had lower association constant for PHA-lectin than T mu lymphocytes, whilst the contrary was found to be true for the other three lectins.

Acetylgalactosamine↗
PubMedDate not supplied

PHA reactivity of spontaneous AKR lymphomas: absolute macrophage requirement.

The study of patients with T cell lymphoproliferative disorders often demonstrates a reduced response to mitogens. The T cell lymphoma in AKR mice has been considered a classic experimental model of T cell leukaemias. In this paper ten spontaneous lymphomas from AKR mice were characterized individually in vitro for PHA reactivity. After 60 h. of culture, spontaneous 3H-Thymidine uptake by nylon wool purified spleen cells from individual lymphomas oscillated between 4.724 and 81.125 cpm. These nylon wool purified leukemic cells were not responsive to PHA (S.I. less than 2.5). When these cells were cocultured with an adequate macrophage concentration in the presence of PHA, all could be considered responsive to the mitogen (S.I. greater than 2.5). Results indicate that AKR leukemic cells are responsive to PHA in an absolutely macrophage dependent way.

AKR murine leukemia virus↗
PubMed1984

During frog ontogeny, PHA and Con A responsiveness of splenocytes precedes that of thymocytes.

The in-vitro proliferation of splenocytes and thymocytes from Xenopus laevis-gilli (hybrid clone LG-15) to the T cell mitogens, concanavalin A (Con A) and phytohaemagglutinin-P (PHA), were examined at specific stages of larval development (stages 51-66 of Nieuwkoop & Faber, 1967) and at 2 months post-metamorphosis. The responses of splenic lymphocytes to each mitogen were significant at all stages with stimulation indices ranging from 1.9 to 50.5 and 2.6 to 45.5 for PHA and Con A, respectively. Stage-related differences in responses of splenocytes to both mitogens suggest two waves of emergence of proliferative activity during development, divided by periods of diminished responsiveness during the metamorphic crisis. In contrast to the responses observed with splenocytes, proliferation of thymocytes cultured with either mitogen was barely detectable, with stimulation indices ranging from 1.2 to 6.9 and 1.4 to 2.9 for PHA and Con A, respectively. These minimal responses were observed only when thymocytes were cultured at relatively high cell density (5 X 10(5) cells/ml); they were not improved by increased or decreased concentrations of mitogen or by increased concentrations of fetal calf serum (5 or 10%) in the medium. Co-culture of larval thymocytes with autologous splenocytes and each mitogen did not consistently increase thymocyte responses suggesting that the defect in thymocyte responsiveness is not due to lack of accessory cells. These findings suggest that if PHA- and Con A-reactive cells are present in the thymus, they are present in relatively low numbers at all stages of larval development. The pattern of early mitogen responsiveness in the spleen at a time when the thymus is unresponsive contrasts with that observed in mammalian development in which thymocytes become responsive to mitogens in fetal stages and mitogen responsiveness appears in the spleen only around the time of birth. The apparent inactivity of larval thymocytes may reflect a population of cells that can become tolerant to those neo-self-antigens that arise during and after metamorphosis. If so, the larval amphibian thymus may provide a model to study the early events of thymocyte 'education' and differentiation in a broader time framework than is possible with fetal mammals.

Animals↗
PubMed1983

[Role of terminal deoxyribonucleotidyl transferase in stimulating lymphocyte DNA synthesis as affected by PHA].

3H-thymidine incorporation was measured in DNA of the human lymphocytes from the peripheral blood after its PHA-stimulation in vitro. The increased PHA-stimulation was established after addition to the medium of exogenous terminal deoxynucleotidyl transferase (TDT) for cultures with small level of PHA-stimulation only. TDT without PHA exerted no stimulating action on the culture of lymphocytes.

Cells, Cultured↗