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PubMed1989

Functional heterogeneity in the process of T lymphocyte activation; barium blocks several modes of T cell activation, but spares a functionally unique subset of PHA-activable T cells.

The effects of the alkaline earth divalent cation Barium (Ba2+) were studied in in-vitro murine polyclonal T cell activation induced with a panel of T cell mitogens consisting of the plant mitogens concanavalin A (ConA), jacalin and phytohaemagglutinin (PHA), a mitogenic anti-Thy1 monoclonal antibody (MoAb), and an anti-murine CD3 MoAb combined with phorbol ester. All modes of T cell activation, except PHA-induced mitogenesis, were blocked in a reversible and dose-related manner by Ba2+. Blockade was evident only if Ba2+ was added within the first 6 h of stimulation, was totally reversed in a competitive fashion by addition of Ca2+ to the medium, and selectively affected interleukin 2 (IL-2) production, without interfering with expression of IL-2 receptor light chains, nor with late IL-2-dependent activated T cell growth. On the other hand, PHA-induced responses stimulated by optimal mitogen doses were resistant to the effects of Ba2+. Ba2+-resistance of PHA responses was due to IL-2-dependent activation and growth of a Ba2+-resistant T cell subset since: (i) limiting dilution analysis demonstrated that this PHA response had a much lower precursor cell frequency than control PHA responses; (ii) proliferation was blocked by anti-IL2 agents, such as cyclosporin A and anti-IL-2 receptor light chain MoAbs, which were much less effective in blocking control PHA responses. Thus, pharmacological use of Ba2+ reveals the existence of a pathway of T cell activation, induced by PHA, with differential interleukin requirements.

Animals↗
PubMed1986

Kinetics of prostaglandin E2 and thromboxane A2 synthesis and suppression of PHA-stimulated peripheral blood mononuclear leucocytes.

The immunomodulatory effects of thromboxane A2 and prostaglandin E2 on peripheral blood mononuclear leucocytes stimulated with PHA in vitro, and the relationship of this to the time-course of their synthesis in culture, were investigated using prostaglandin E2, a thromboxane A2 synthesis inhibitor (UK37248), a thromboxane A2 mimic (U46619) and a thromboxane A2 receptor blocker (EP045). The inhibitory effect of prostaglandin E2 on PHA-induced human peripheral blood mononuclear leucocyte proliferation diminishes if the addition of PGE2 is delayed. If added 4 hr after a maximum concentration of PHA (5 micrograms/ml), the effect of PGE2 was reduced by 60%. If a submaximal concentration of PHA (1 microgram/ml) was used, the effect of PGE2 was not reduced if added 4 hr later but fell by about 60% after 16 hr. UK37248 moderately inhibited PHA-induced activation while substantially inhibiting thromboxane A2 synthesis and simultaneously enhancing PGE2 synthesis. The enhanced accumulation of PGE2 occurs while sensitivity to PGE2 is dropping. U46619, exogenously applied as a thromboxane A2 mimic, inhibited PHA-induced activation at concentrations that did not significantly alter PGE2 synthesis. EP045, which may modulate the effects of endogenous thromboxane A2 by blocking receptors, did not alter PHA-induced activation. We conclude that thromboxane A2 may have a role in inhibiting PHA-induced activation on the basis of the effect of U46619. However, this study highlights difficulties in utilizing prostaglandin and thromboxane receptor and synthesis inhibitors to examine their endogenous role in the modulation of mitogen-induced activation in vitro. If sensitivity to the purported endogenous substance is limited to the early stages of culture and if only low levels are synthesized at this early stage, then blocking drugs would have little effect.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1981

PHA skin test-correlation with migration inhibition but not with peripheral blood lymphocytes (PBL) subpopulations. With 1 figure.

Results of the PHA skin test correlate with prognosis of cancer patients (W. Wiktor-Jedrzejczak [17] ). However, its clinical interpretation is faded by not known character of this reaction. In the present study PHA skin test was performed on 50 subjects simultaneously with: 1. sealed capillary migration inhibition test in the presence of various concentrations of PHA; 2. E and EAC rosette tests for quantitation of T and B lymphocytes. Skin reaction to 1 microgram of purified PHA (Wellcome) was found to correlate with migration inhibition performed using suboptimal doses of PHA-P (Difco). -No correlation was found between leukocyte and lymphocyte absolute count and PHA skin test. Neither proportions nor absolute numbers of E+, and EAC+ and null cells correlated with PHA skin test. On several occasions the test persisted positive despite absence of lymphocytes in peripheral blood of patients. -These studies further suggest that PHA skin test has certain characteristics similar to DTH reactions and that changes of the test do not simply reflect changes in PBL subpopulations.

Cell Migration Inhibition↗
PubMed1980

[The effect of human cord plasma on the incorporation of 3H-thymidine by PHA-stimulated peripheral blood lymphocytes of cervical cancer patient (author's transl)].

It has been proposed that human cord plasma can suppress the PHA response of adult lymphocytes. To compare the suppressive effects between plasma from cancer patients and human cord plasma, we investigated the PHA responses of lymphocytes which were sampled from patients with various stages of cervical cancer and cancer free women, by adding cancer auto-plasma, human cord plasma and control plasma. The PHA responses of normal lymphocytes cultured with plasma from patients with 2nd and advanced stage of cancer were suppressed, but they were not suppressed by the plasma from O-I stage of cancer. The addition of control plasma enhanced PHA responses of lymphocytes of the 2nd and advanced stage of cancer, but no changes were observed in the lymphocytes from O-I stage of cancer. These results suggest that inhibitory factor does not appear in the plasma from the patients with O-I stage of cervical cancer. Human cord plasma moderately suppressed the PHA responses of normal lymphocytes; it also suppressed the PHA responses of lymphocytes from O-I stage of cancer. However, the PHA responses of lymphocytes from 2nd and advanced stage of cancer were improved significantly. Cord plasma may have a factor which promotes the PHA responses of lymphocytes from advanced cancer.

Adult↗
PubMed1990

Efferent projections of the subthalamic nucleus in the squirrel monkey as studied by the PHA-L anterograde tracing method.

The organization of the efferent connections of the subthalamic nucleus was studied in the squirrel monkey (Saimiri sciureus) by using the lectin Phaseolus vulgaris-leucoagglutinin (PHA-L) as an anterograde tracer. At the level of the basal forebrain, anterogradely labeled fibers and axon terminals were mostly found in the striatopallidal complex and the substantia innominata. In cases in which the PHA-L injection sites were placed in the central or the lateral third of the subthalamic nucleus, numerous anterogradely labeled fibers were seen to arise from the injection loci and innervate massively the globus pallidus. At pallidal levels the fibers formed bands lying parallel and adjacent to the medullary laminae. The number and the complexity of the topographical organization of these bands varied with the size and the location of the PHA-L injection site. When examined at a higher magnification, the bands of subthalamopallidal fibers appeared as rich plexuses of short axon collaterals with small bulbous enlargements that closely surrounded the cell bodies and primary dendrites of pallidal cells. In contrast, PHA-L injection involving the medial tip of the subthalamic nucleus did not produce bandlike fiber patterns in the globus pallidus. Instead, the labeled fibers formed a diffuse plexus occupying the ventral part of the rostral pole of the globus pallidus as well as the subcommissural pallidal region. The substantia innominata contained a moderate number of labeled fibers and axon terminals following injection of PHA-L in the medial tip of the subthalamic nucleus. A small to moderate number of anterogradely labeled fibers were seen in the putamen after all PHA-L injections. These subthalamostriatal fibers were long, linear, and branched infrequently. At midbrain level the substantia nigra contained a significant number of anterogradely labeled fibers and axon terminals following PHA-L injection in the subthalamic nucleus. The subthalamonigral fibers descended along the ventromedial part of the cerebral peduncle and swept laterally to reach their target. Most of these fibers formed small plexuses along the base of the pars reticulata, whereas a few others ascended along the cell columns of the pars compacta that impinged deeply within the pars reticulata. More caudally in the brainstem, a small number of fibers occurred in the area of the pedunculopontine nucleus and in the periaqueductal gray. These findings indicate that besides its well-known connection with the pallidum, the subthalamic nucleus gives rise to widespread projections to other components of the basal ganglia in primates.

Animals↗
PubMed1990

Phaseolus vulgaris leucoagglutinin (PHA-L): a neuroanatomical tracer for electron microscopic analysis of synaptic circuitry in the cat's dorsal lateral geniculate nucleus.

Phaseolus vulgaris leucoagglutinin (PHA-L) is a plant lectin that is anterogradely transported by neurons in the central nervous system. PHA-L is selectively taken up by cells at iontophoretic injection sites and, when immunohistochemically demonstrated, labels individual neurons completely, including their dendrites, axons, and terminal boutons. PHA-L is generally not taken up by fibers passing through the injection site and, because it produces a Golgi-like staining of even very fine axons over long distances, it is sometimes possible to light microscopically reconstruct individual neurons and their entire axon terminal arbors. When prepared for electron microscopy, the PHA-L-labeled terminals are densely and completely stained, allowing their synaptic relationships to be defined. These properties make PHA-L advantageous for studying the patterns of projection and the modes of termination of select groups of neurons in their target nuclei. We used PHA-L to study the extraretinal innervation of the cat's dorsal lateral geniculate nucleus, a thalamic visual center. Although much is known about the retinal contribution to geniculate synaptic circuitry, relatively little is known about other sources of innervation, even though these provide the majority of synaptic terminals in the nucleus (Guillery: Z. Zellforsch., 96:1-38, 39-48, 1969; Wilson et al.: Proc. R. Soc. Lond. [Biol.], 221:441-436, 1984). We used both light and electron microscopy to describe synaptic circuitry from three extraretinal sources of projections to the lateral geniculate nucleus: the visual cortex, the perigeniculate nucleus, and the parabrachial region of the brainstem. Cortical terminals labeled with PHA-L were small and formed asymmetrical synaptic contacts onto small-caliber dendrites of geniculate neurons. Perigeniculate terminals formed symmetrical synaptic contacts primarily onto small-caliber dendrites, but some synapses were also formed onto the proximal, retinorecipient portions of geniculate dendrites. Parabrachial terminals synaptically contacted the retinorecipient portions of dendritic appendages and shafts, small-caliber dendrites, and the specialized dendritic (F2) terminals of geniculate interneurons. The symmetry of the parabrachial synaptic contacts was variable and was related to the postsynaptic target. Contacts onto dendritic appendages were asymmetrical while those onto dendritic shafts and F2 terminals were symmetrical. Our data suggest that in unlabeled material these brainstem terminals would be difficult to distinguish from cortical or perigeniculate profiles. The positioning of the parabrachial input onto the retinorecipient portions of geniculate dendrites indicates that this projection is well situated to control primary retinal transmission through the nucleus, while the location of most cortical and perigeniculate innervations implicates them in secondary feedback interactions or other aspects of geniculate function.

Animals↗
PubMed2004

Evolution of polyhydroxyalkanoate (PHA) production system by "enzyme evolution": successful case studies of directed evolution.

Biotechnological studies towards the biosynthesis of polyhydroxyalkanoates (PHAs) biopolyesters have extensively progressed through the development of various metabolic engineering strategies. Historically, efficient PHA production has been achieved using the fermentation technology of naturally occurring PHA-producing bacteria based on external substrate manipulation (1st generation), and subsequent reinforcement with recombinant gene technology (2nd generation). More recently, "enzyme evolution" is becoming the 3rd generation approach for PHA production. A break-through in the chemical synthesis of macromolecules with desirable properties was achieved by the development of prominent chemical catalysts via "catalyst evolution", as represented by a series of Ziegler-Natta catalysts. Thus, one can easily accept the concept that the molecular evolution of the biocatalysts (enzymes) relevant to PHA synthesis will provide us with a chance to create novel PHA materials with high performance. The first trial of an in vitro enzyme evolution in PHA biosynthesis was reported by our group in 2001. The following literature data, as well as our own experimental results devoted to this new approach, have been accumulated over a short time. This review article focuses specifically on the concept and current case studies of the application of "enzyme evolution" to PHA biosynthesis.

Acyltransferases↗
PubMed1984

An anterograde neuroanatomical tracing method that shows the detailed morphology of neurons, their axons and terminals: immunohistochemical localization of an axonally transported plant lectin, Phaseolus vulgaris leucoagglutinin (PHA-L).

A new neuroanatomical method for tracing connections in the central nervous system based on the anterograde axonal transport of the kidney bean lectin, Phaseolus vulgaris-leucoagglutinin (PHA-L) is described. The method, for which a detailed protocol is presented, offers several advantages over present techniques. First, when the lectin is delivered iontophoretically, PHA-L injection sites as small as 50-200 micron in diameter can be produced, and are clearly demarcated since the neurons within the labeled zone are completely filled. Second, many morphological features of such filled neurons are clearly demonstrated including their cell bodies, axons, dendritic arbors and even dendritic spines. Third, there is some evidence to suggest that only the neurons at the injection site that are filled transport demonstrable amounts of the tracer, raising the possibility that the effective injection site can be defined quite precisely. Fourth, even with the most restricted injections, the morphology of the labeled axons and axon terminals is clearly demonstrated; this includes boutons en passant, fine collateral branches, and various terminal specializations, all of which can be visualized as well as in the best rapid Golgi preparations. Fifth, when introduced iontophoretically, PHA-L appears to be transported preferentially in the anterograde direction; only rarely is it transported retrogradely. Sixth, PHA-L does not appear to be taken up and transported effectively by fibers of passage. Seventh, there is no discernible degradation of the transported PHA-L with survival times of up to 17 days. Finally, since the transported marker can be demonstrated with either peroxidase or fluorescent antibody techniques, it may be used in conjunction with other neuroanatomical methods. For example, double anterograde labeling experiments can be done using the autoradiographic method along with immunoperoxidase localization of PHA-L, and the retrogradely transported fluorescent dyes can be visualized in the same tissue sections as PHA-L localized with immunofluorescence techniques.

Animals↗
PubMedDate not supplied

PHA production by activated sludge.

The production of polyhydroxyalkanoate by anaerobic-aerobic activated sludge was reviewed concentrating on the biochemical mechanisms and on the trials to increase polyhydroxyalkanoate (PHA) content in activated sludge. The anaerobic aerobic activated sludge system selects microorganisms with the capabilities to couple glycolysis, polyphosphate degradation, and PHA accumulation for anaerobic substrate uptake. Some of the PHA-related metabolisms observed there have not been seen in pure cultures so far. Such metabolisms are the formation of PHA containing 3-hydroxy-2-methylvalerate, and '3-hydroxyvalerate fermentation' in which glucose or glycogen is converted to 3-hydroxyvalerate-rich PHA while yielding energy. The PHA content of activated sludge can be increased up to 62% by applying a microaerophilic-aerobic activated sludge process. PHA production by activated sludge is worth investigation.

Aerobiosis↗
PubMed1997

Functional expression of the PHA synthase gene phaC1 from Pseudomonas aeruginosa in Escherichia coli results in poly(3-hydroxyalkanoate) synthesis.

The potential of the production of polyhydroxyalkanoates (PHA), consisting of medium-chain-length (MCL) hydroxyfatty acids (C5-C14), in recombinant Escherichia coli was investigated. E. coli mutants affected in fatty acid degradation and fatty acid de novo synthesis were employed. We established the functional expression of the Pseudomonas aeruginosa PHA synthase gene phaC1. The coding region of phaC1 was subcloned via PCR into vector pBluescript SK-. The resulting plasmid pBHR71 enabled functional expression of phaC1 under lac promoter control and conferred synthesis and accumulation of PHA to various strains of E. coli. PHA synthesis was analysed with respect to the carbon source in various E. coli fad and fab mutants. This study provided evidence that intermediates of the fatty acid beta-oxidation can be directed to PHA synthesis and that 3-hydroxydecanoyl-CoA is the main substrate for PHA synthase PhaC1 from P. aeruginosa. The E. coli fadB mutant LS1298 containing plasmid pBHR71 and cultivated in LB medium containing 0.5% (w/v) decanoate revealed the strongest accumulation of PHA contributing to about 21% of the cellular dry weight, which was composed of 2.5 mol% 3-hydroxyhexanoate, 20 mol% 3-hydroxyoctanoate, 72.5 mol% 3-hydroxydecanoate and 5 mol% 3-hydroxydodecanoate.

Acyltransferases↗
PubMed2006

PHA-680632, a novel Aurora kinase inhibitor with potent antitumoral activity.

PURPOSE: Aurora kinases play critical roles during mitosis in chromosome segregation and cell division. The aim of this study was to determine the preclinical profile of a novel, highly selective Aurora kinase inhibitor, PHA-680632, as a candidate for anticancer therapy. EXPERIMENTAL DESIGN: The activity of PHA-680632 was assayed in a biochemical ATP competitive kinase assay. A wide panel of cell lines was evaluated for antiproliferative activity. Cell cycle analysis. Immunohistochemistry, Western blotting, and Array Scan were used to follow mechanism of action and biomarker modulation. Specific knockdown of the targets by small interfering RNA was followed to validate the observed phenotypes. Efficacy was determined in different xenograft models and in a transgenic animal model of breast cancer. RESULTS: PHA-680632 is active on a wide range of cancer cell lines and shows significant tumor growth inhibition in different animal tumor models at well-tolerated doses. The mechanism of action of PHA-680632 is in agreement with inhibition of Aurora kinases. Histone H3 phosphorylation in Ser10 is mediated by Aurora B kinase, and our kinetic studies on its inhibition by PHA-680632 in vitro and in vivo show that phosphorylation of histone H3 is a good biomarker to follow activity of PHA-680632. CONCLUSIONS: PHA-680632 is the first representative of a new class of Aurora inhibitors with a high potential for further development as an anticancer therapeutic. On treatment, different cell lines respond differentially, suggesting the absence of critical cell cycle checkpoints that could be the basis for a favorable therapeutic window.

Animals↗
PubMed2005

Synthesis of polyhydroxyalkanoate (PHA) from excess activated sludge under various oxidation-reduction potentials (ORP) by using acetate and propionate as carbon sources.

Accumulation of poly hydroxyalkanoate (PHA) from excess activated sludge (EAS) was monitored and controlled via the oxidation-reduction potential (ORP) adjusting process. The ORP was adjusted and controlled by only regulating the gas-flow rate pumped into the cultural broth in which sodium acetate (C2) and propionate (C3) were used as carbon sources. Productivity of PHA and the PHA compositions at various C2 to C3 ratios were also investigated. When ORP was maintained at +30 mV, 35% (w/w) of PHA of cell dry weight obtained when C2 was used as sole carbon source. The PHA copolymer, poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), accumulated by EAS with different 3-hydroxyvalarate (3HV) molar fractions ranged from 8% to 78.0% when C2 and C3 was used as sole carbon source, By using ORP to monitor and control the fermentation process instead DO meter, the ORP system provided more precise control to the PHA accumulation process from EAS under low dissolved oxygen (DO) concentrations. Adjusting the C2 to C3 ratios in the media could control the composition such as the 3HV/3HB ratios of the PHBV. Furthermore, it might be an effective way to adjust the 3HV molar fractions in PHBV by controlling the DO concentration via the ORP monitoring system. The 3HV molar fractions in the PHBV declined with increasing ORP from -30 mV to +100 mV by adjusting the gas-flow rate (i.e. the DO concentration). It is concluded that the DO plays a very important role in the synthesis of 3HV subunits in PHBV co-polymer from the EAS. Therefore, a hypothetic metabolic model for PHA synthesis from EAS was proposed to try to explain the results in this study.

Acetates↗
PubMed1981

Differences in mitogenic responses of murine T cells to two distinct phytohemagglutinin (PHA) subcomponents.

Two distinct mitogenic subcomponents of phytohemagglutinin (PHA)--leucoagglutinin (LA) and "purified" PHA--apparently stimulated different subpopulations of murine T cells. In the DBA/2J strain, the mitogenic responses of splenic lymphocytes to LA reached maximal levels after 24 to 36 hr exposure and almost completely disappeared by 48 hr, whereas maximal responses to PHA were maintained after 48 hr incubation. The levels of LA-responding T cells were highest in DBA/2J spleens at 5 weeks of age but markedly declined by 9 weeks of age, whereas thymic levels of LA-responding T cells reached a maximum at 9 weeks of age and remained maximal past 15 weeks of age. PHA-responding cells, in contrast, reached maximal levels in both the spleen and thymus of DBA/2J mice at 9 weeks of age. In C57BL/6J mice, splenic and thymic lymphocytes responded similarly to both components, except that the response of splenic lymphocytes to PHA reached a maximum after shorter incubation time and declined sooner than their response to LA. The mitogenic responses of C57BL/6J thymocytes to both components were already at their peak by 5 weeks of age and almost totally disappeared by 9 weeks, whereas the responses of splenic lymphocytes were maximal at 9-15 weeks of age. The responses of DBA/2J splenocytes to LA was significantly augmented by PHA, but LA markedly suppressed the proliferative responses to PHA.

Aging↗
PubMed1990

Relationship between PO-AH and PHA in the effects of EA at neiguan in the rabbit.

The activity of PHA neurons was extracellularly recorded by using glass microelectrodes and the mutual relationship between PO-AH and PHA during the regulation activity of EA was analysed. The results were as follows: 1. The activity of most PHA neurons could be changed by PO-AH stimulation. 2. The activity of some PHA neurons could be affected by AMI. 3. The AMI-induced PHA neurons activity could be changed by EA at "Neiguan". 4. The effect of EA could be enhanced in some PHA neurons by PO-AH stimulation under EA. The findings suggest that PO-AH and PHA possess some coordination effect in the regulation of EA at "Neiguan" on the functional activity of the heart.

Acupuncture Points↗
PubMed1989

[Response of human lymphocytes to phytohemagglutinin (PHA) as measured by fluorescence polarization technique--differences between malignant conditions and benign or healthy conditions].

Percoll gradient (density: 1.081 g/cm3) centrifugation of peripheral venous blood yielded two layers of mononuclear cells. Preliminary study using lower lymphocyte layer revealed that there were significant differences in lymphocyte fluorescence polarization changes after PHA stimulation between malignant conditions and benign or healthy conditions, while such differences were not apparent by use of upper lymphocyte layer. According to these preliminary results, we studied fluorescence polarization changes after PHA stimulation in lower lymphocyte layer obtained from 242 individuals, including 49 apparently healthy women, 93 patients with benign gynecological tumor, 17 patients with severe dysplasia of the uterine cervix and 83 patients with malignant gynecological tumor. Stimulation index (R) was defined as the ratio between the degree of polarization before PHA stimulation (P CONTROL) and the degree of polarization after PHA stimulation (PPHA): R = PPHA/PCONTROL. R values of less than unity (R less than 1) indicate stimulation with PHA, and R values of greater than unity (R greater than or equal to 1), non-stimulation with PHA, respectively. R values of less than unity (R less than 1) was found in 118 of 142 (83.1%) healthy women or patients with benign tumor, 5 of 17 (29.4%) patients with cervical dysplasia, and 13 of 83 (15.7%) patients with malignant tumor, respectively. Preoperative R values of greater than unity decreased to R values of less than unity in 17 of 20 (85.0%) patients who received complete resection of the malignant lesion, while decline of R values was noted only in 8 of 22 (36.4%) patients who received incomplete resection of the lesion and/or chemotherapy or radiation. Present findings indicate that fluorescence polarization changes after PHA stimulation in lymphocytes isolated by Percoll gradient facilitate feasible detection of various malignancies.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytoplasm↗
PubMed1979

Phytohemagglutinin (PHA) skin test. Characterization of immunological properties and clinical application.

Immunological properties of phytohemagglutinin (PHA) skin reaction were investigated by animal and clinical experiments. In the guinea pigs an intradermal dose of PHA-P produced erythema and induration with a maximal response at 24 hours after the injection. Histologically it was characterized by perivascular infiltration of lymphoid cells in the dermis and subcutis, being similar to that of tuberculin (PPD) skin reaction. PHA skin reaction, however, showed some difference from that of PPD in the initial cellular response in that the former was composed of small mononuclear cells and granulocytes with rapid development and the latter was composed of large mononuclear cells (macrophages) and granulocytes with slow development. Intradermal injection of 1:1000 dilution of PHA-P produced a similar erythema in man. In 39 of 59 patients with connective tissue diseases, the results of the in vivo (skin test) and in vitro (lymphocyte transformation) response to PHA correlated well. In the 59 patients, the incidence of the positive rate of the PHA tests (55.9%) was significantly higher than that of the DNCB test (33.9%) and of the PPD test (23.7%). These observations suggest that the PHA skin test has properties of delayed hypersensitivity and is highly sensitive and that it may be a useful measure of cell-mediated immunity.

Adult↗
PubMed1980

In vitro immune response of human peripheral lymphocytes. VI. Distribution and characterization of precursors for PHA- and protein A-induced colony-forming B cells.

B cells from peripheral blood or cord blood formed colonies by stimulation with either PHA or protein A. On the other hand, tonsillar B cells did not form protein A-induced colonies, although PHA-induced colony formation was comparable to that observed in peripheral B cells. Lack of protein A-induced colony formation in tonsillar B cells was not due to the defect of helper T cells in preculture or to the presence of suppressor cells but was due to the absence of precursors for colony formation. The result showed that PHA- and protein A-induced colony-forming cells belonged to distinct subsets of B cells. Depletion of mu-bearing cells from peripheral B cells abrogated both PHA- and protein A-induced colony formation. Depletion of delta-bearing cells did not affect PHA- and protein A-induced colony formation and the population enriched with delta-bearing cells also showed colony formation. Depletion of complement receptor (CR)-positive cells removed precursors for both PHA- and protein A-induced colony formation. These results showed that precursor cells for PHA- and protein A-induced colony formation were IgM+, IgD+ and CR+ or IgM+, IgD- and CR+.

Animals↗
PubMed1983

Human T lymphocytes in aging and malignancy: abnormalities in PHA-induced Ia antigen expression and in functional activity in autologous and allogeneic MLR.

T lymphocytes from patients with solid tumors and from aged donors are abnormal in their expression of Ia antigens following in vitro stimulation with phytohemagglutinin (PHA). Ia antigens were not detected on PHA-activated T lymphocytes from 15 of 27 patients with solid tumors. The abnormality in T lymphocytes from 25 donors older than 60 years was evidenced by a reduction in the percentage of T cells acquiring Ia antigens following stimulation with suboptimal amounts of PHA and by a delayed appearance of those antigens. In both groups of donors the defect in Ia antigen expression by PHA-activated T cells did not correlate with the reduced [3H]thymidine uptake. PHA-activated T cells from aged donors and from patients with solid tumors were poorly stimulatory in autologous and allogenic mixed lymphocyte reactions. Furthermore, T lymphocytes from these two groups of donors displayed a reduced proliferative response to autologous non-T cells, but a normal proliferative response to allogeneic PHA-activated T cells and to non-T cells from control subjects.

Adult↗