Dietary phytohaemagglutinin slows down the proliferation of a mouse plasmacytoma (MPC-11) tumour in Balb/c mice

Ten days after subcutaneous injection of MPC-11 cells, plasmacytoma tumours which developed in female Balb/c mice fed on a diet containing the kidney bean lectin phytohaemagglutinin (PHA) at a concentration of 7.0 mg g-1 diet, weighed only about 38% of those fed a lactalbumin (La) control diet. The reduction in growth caused by the lectin appeared to occur in a dose-dependent manner but the values did not reach significance before PHA was at a concentration of 7.0 mg g-1 diet. Pre-feeding with the lectin caused a further 50% reduction in tumour weight. In contrast to the reduction in tumour size the inclusion of PHA in the diet elevated the mean dry weight of the small intestine in a dose-dependent manner, values reaching significance at 3.5 mg g-1 diet. The results showed that gut hyperplasia was able to occur even in the presence of the developing tumour. A lypolytic effect of PHA occurred at high concentration. The observations suggest that PHA itself does not have a direct effect on the tumour cells, but an inter-relationship between gut hyperplasia and decreased tumour growth is indicated.

Phytohemagglutinin-induced gut hyperplasia and the growth of a mouse lymphosarcoma tumor

NMRI mice injected subcutaneously with Krebs II lymphosarcoma cells and fed on a diet containing the kidney bean lectin phytohemagglutinin (PHA) within the range 0.45-7.0 mg/g diet, developed tumors during a 10 day period which on average were only 35% of the dry weight of tumors in lactalbumin (La) fed mice (control). The reduction in growth occurred in a dose-dependent manner in the range 0.45-3.5 mg/g diet. The degree of hyperplasia of the small intestine in response to feeding the PHA diets was higher in non-injected compared to injected mice. A lipolytic effect of PHA was observed above 1.75 mg/g diet in control mice and the highest concentration had a major effect on body weight. Since the index of hyperplasia at the lowest PHA concentration tested did not correlate with the reduction in tumor size, it is suggested that other factors in addition to the initial lectin-induced gut hyperplasia are involved in slowing down the progression of tumor growth.

Organization of identified fiber tracts in the rat fimbria-fornix: an anterograde tracing and electron microscopic study

The fimbria is a major route for afferent and efferent fibers of the hippocampal formation. However, little is known about the intrinsic organization of the fimbria-fornix complex. In this study, the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHAL) was used to analyze the ultrastructure and topography of identified fiber tracts within the fimbria-fornix. Septo-hippocampal fibers are loosely distributed throughout the fimbria-fornix. Commissural fibers cross the midline in the ventral hippocampal commissure and form a tight fiber bundle in the fimbria. Crossed entorhino-hippocampal fibers cross the midline in the ventral hippocampal commissure rostral to the commissural fiber bundle, and crossed entorhino-entorhinal fibers pass through the dorsal hippocampal commissure. This suggests a topographical organization of fiber tracts within the fimbria-fornix that reflects the laminar organization of the hippocampal target structure: fibers of the diffusely terminating septohippocampal projection are loosely distributed throughout the fimbria-fornix, while those projections that are known to terminate in specific laminae of the hippocampal formation (commissural projection, crossed entorhino-hippocampal projection) form fiber bundles within the fimbria and the ventral hippocampal commissure.

Switching between control and phytohaemagglutinin-containing diets affects growth of Krebs II ascites cells and produces differences in the levels of putrescine, spermidine and spermine

Almost twice as many ascites tumour cells were recovered from mice pre-fed for 3 days on a lactalbumin (La)-based control diet, injected with Krebs II ascites cells and then maintained on the same diet for a further 8 days, when compared with mice fed on a phytohaemagglutinin-containing (PHA) diet for the whole period. A dietary switch on the day of injection of tumour cells produced an intermediate effect; mice switched to the La diet after pre-feeding on PHA for 3 days developed somewhat more tumour cells than when the opposite dietary switch was performed. The polyamine content in the tumour cells was lowest in the mice fed on La, and highest in mice fed PHA for the duration of the experiment, respectively. Since large amounts of extraneous polyamines are required in order to sustain tumour growth, and the hyperplastic growth of the gut which occurs in response to injesting the lectin is a polyamine-dependent process, it is evident that the two growth signals compete with one another for important nutrients/growth factors, including polyamines.

[In vitro synergic lymphocyte stimulation in HIV-1 infected patients using inosine derivatives and radio-detoxified endotoxin]

Restoration of immune functions through promoting cell cycle might delay acquired immunodeficiency syndrome development. Therefore, stimulation of peripheral lymphocytes of human immunodeficiency virus-1 infected patients in successive clinical stages was studied by phytohaemagglutinin and other stimulants. In vitro blastogenesis was quantitated by 3H-thymidine uptake. Stimulation by phytohaemagglutinin decreased in patients with AIDS related complex to 63.1%, with AIDS to 13.6% of control values. Small amount of recombinant interleukin-2 or indomethacin solely not promoting lymphocytes, increased response to phytohaemagglutinin minimally. Alone ineffective methyl-ester and methyl-phosphonate inosine derivatives augmented phytohaemagglutinin-response of controls and patients with AIDS related complex by approx. 1.5-fold, but the effect in the case of AIDS patients was minimal. Radio-detoxified endotoxin alone or in combination with phytohaemagglutinin stimulated lymphocytes of both controls and patients with AIDS related complex slightly. Lymphocyte stimulation of patients with AIDS related complex was augmented in concentration-dependent manner, and by synergic effect it approached phytohaemagglutinin-stimulated blastogenesis of controls. Anergy due to human immunodeficiency virus-1 infection damages synchronisation of secondary messenger systems induced on cell surface receptors, therefore their selective influence by recombinant interleukin-2 or indomethacin is less efficient. Inosine derivatives promote cell cycle by inhibiting cyclic adenosine 3',5'-monophosphate production. In the early stage of virus infection, radio-detoxified endotoxin might bind to receptors of immature T cells and facilitate cell cycle through cyclic guanosine 3',5'-monophosphate stimulation. The clinical trials of radio-detoxified endotoxin (Tolerin) have already been launched.

Effect of injection site on cutaneous basophil hypersensitivity response to phytohemagglutinin

Cutaneous basophil hypersensitivity response to phytohemagglutinin (PHA) is frequently used as a measure of cell-mediated immune response in chickens. Several anatomical sites have been used to measure this response. No correlation between response level at different sites, however, has been reported. This study compares responses to PHA by using two different injection sites (wing web and interdigital skin of the foot) in White Leghorn chickens. Response at each individual site was comparable whether the bird received a PHA injection at that site alone or at both sites. Correlations between responses at the two sites were not different from zero [-.1733 (P = .44)]. These data indicate that caution must be exercised in comparing cell-mediated immune responses when different PHA injection sites have been used to assess response.

Multiple striatal representation in primate substantia nigra

The pattern of arborization of the striatonigral fibers in the squirrel monkey (Saimiri sciureus) was studied with Phaseolus vulgaris-leucoagglutinin (PHA-L) and biocytin as anterograde tracers. Single, small injections of PHA-L or biocytin in either the caudate nucleus or the putamen give rise to at least four distinct, nonoverlapping but interconnected fiber plexuses that are distributed throughout the rostrocaudal extent of the substantia nigra pars reticulata (SNr) according to a strikingly precise and constant sequence. These plexuses, which comprise numerous fibers that closely entwine unlabeled dendrites of SNr neurons (woolly fibers), often lie at the base of dopaminergic cell columns of the substantia nigra pars compacta (SNc). Long and varicose fibers emerge dorsally from SNr plexuses and climb along the ventrally oriented dendrites of dopaminergic SNc neurons, as visualized with tyrosine hydroxylase immunohistochemistry. These fibers appear to contact en passant both dendrites and cell bodies of dopaminergic neurons belonging to the ventral tier of SNc. Anterograde double-labeling experiments involving small deposits of PHA-L and biocytin in adjacent areas of the caudate nucleus and the putamen reveal that neighboring striatonigral cell populations form two distinct sets of terminal plexuses that remain well segregated throughout SNr. Plexuses from the two sources interdigitate in some parts of SNr, but never intermix. Furthermore, the woolly fibers in these plexuses are composed exclusively of either PHA-L- or biocytin-labeled elements; none of them display both types of labeling. These results reveal that the striatonigral projection in primates is highly divergent and that the striatum has multiple representations at nigral levels. They also indicate that striatal information is conveyed to the substantia nigra in a highly ordered fashion through multiple segregated channels.

Divergent feedback connections from areas V4 and TEO in the macaque

Extrastriate areas TEO and V4 have been associated with form and color vision. Area V4 has also been suggested to participate in processes concerned with attention, stimulus salience, and perceptual learning. In a continuing effort to elucidate the connectional interactions and microcircuitry of these areas, we describe in this report the pattern of feedback connections from TEO and V4. Connections were demonstrated by injections of the high-resolution anterograde tracers PHA-L or biocytin and further analyzed by reconstruction of 25 individual axons through serial sections. This analysis yielded several new results: (1) Both areas TEO and V4 have widespread feedback connections (defined by their preferential termination in layer 1 and avoidance of layer 4). From TEO, there are dense projections to area V4 and moderate ones to V2 and V1. From V4, there are dense projections to V2 and moderate ones to V3 and V1. (2) Terminal fields span large territories in area V1, up to 6.0 mm in the case of axons originating from TEO; up to 5.0 mm in the case of axons originating from V4. In V2, fields tend to be smaller, between 3.0-5.0 mm. (3) Many axons from TEO and some from V4 have terminations in both areas V1 and V2. (4) Because individual terminal clusters and segments are often larger than cytochrome oxidase compartments, especially in V1, we suggest they may not be correlated with this compartmental organization. These results are consistent with the hypothesis that feedback connections may contribute to processes other than perceptual discrimination.

[Pharmacological modification of prolactinemia. Effects on cellular immune function in normal subjects]

Prolactin markedly influences cellular and humoral immunity in animals, but there is little information on its role in men. The aim of this work was to study the immune effects of pharmacological modification of prolactin levels in 5 healthy individuals. Peripheral blood mononuclear cell proliferative response to mitogens and antigens, interleukin-2 (IL-2) production, soluble and membrane IL-2 receptor expression in peripheral blood mononuclear cells and serum soluble IL-2 receptors were successively measured during normoprolactinemia, during bromocriptine induced hypoprolactinemia and during metoclopramide induced hyperprolactinemia. There was a significant increase in cellular proliferation during hypoprolactinemia when compared with hyperprolactinemia. No concomitant changes in soluble or membrane receptor expression or IL-2 production were observed. It is concluded that lymphocyte proliferative response to mitogens is dependent on prolactin levels in man and that this effects is not mediated by IL-2 or its receptors. These results may be potentially relevant in clinic since changes in serum prolactin have been described in different autoimmune diseases.

Adoptive immunotherapy of advanced renal cell cancer using PHA-stimulated autologous lymphocytes

Patients with advanced renal cell carcinoma, previously failed maximal treatment with standard chemo-hormonal-radiation therapies, were treated with plant lectin phytohemagglutinin (PHA)-stimulated autologous peripheral blood lymphocytes in a 10-year study with a 16-year follow up period. In a phase I-II setting, 52 patients were given subcutaneously 40-80 x 10(6) PHA-stimulated lymphocytes weekly for 3 weeks and then escalated to a maximum number of 80 x 10(9) lymphocytes over the next 9 weeks at 3 week intervals. In vitro blastogenesis under study conditions (10 micrograms/ml PHA for 72 hr) measured by [3H]thymidine uptake was optimal with lymphocyte stimulating indexes approaching 300. Lymphocytes obtained from patients with breast cancer, melanoma and renal cell carcinoma responded to PHA similarly to those from normal volunteers. All patients that responded developed erythematous reactions at the sites of injection; malaise, joint paint and chill-fever for 24-48 hr. The patients that responded the best were those with at least 1 positive reaction out of 4 skin tests (tuberculosis, yeast, dermatophytin, mumps) prior to therapy. All toxicity was transient and did not exceed Grade I based on criteria of the Southwest Oncology Group. The majority of patients developed a lymphopenia in the first 24 hr followed by a lymphocytosis 48-72 hr later. For some patients the lymphocytosis was as much as 30% atypical lymphocytes. Of 41 evaluable patients, there were 5 complete responses, 8 partial responses, 3 stable diseases, and 25 progressive disease. The overall response rate was 32% and the median survival was 2.8 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of cytokine gene expression in CD4+ and CD8+ T cells after activation with phorbol myristate acetate and phytohaemagglutinin

Cytokines are important mediators involved in the development of effector cells and in the regulation of immune responses. The gene expression of these mediators in T cell subset has yet to be fully elucidated. Using sensitive reverse transcription-polymerase chain reaction (RT-PCR), the kinetics of cytokine gene expression in human CD4+ and CD8+ T cells were examined. CD4+ T cells were more readily activated by phorbol myristate acetate (PMA) and phytohaemagglutinin (PHA) than CD8+ T cells in terms of the IL-2 receptor (IL-2R) mRNA expression. Quantitative differences in cytokine gene expression between CD4+ and CD8+ T cells were confirmed and higher levels of cytokine mRNAs were induced in CD4+ than in CD8+ T cells. Early induction of IL-2 mRNA was observed in both T cell subsets. The demonstration of different kinetics of cytokine gene expression illustrates one of the examples of the complexity of immunoregulation. The differential response of cytokine gene expression in different T cell subsets should be taken into consideration when clinical studies in cytokine production by peripheral blood mononuclear cells are interpreted.

Anatomical evidence for genetic differences in the innervation of the rat spinal cord by noradrenergic locus coeruleus neurons

Pontospinal noradrenergic neurons located in the A5, A6 (locus coeruleus, LC), and A7 cell groups are the major source of the noradrenergic innervation of the spinal cord. We have recently examined the specific terminations of these three cell groups in the spinal cord and found that the LC provides the major noradrenergic innervation of the ventral horn, while the A7 and A5 cell groups innervate the dorsal horn and intermediate zone, respectively. However, the results of similar experiments from another laboratory have shown that noradrenergic neurons in the locus coeruleus primarily innervate the dorsal horn, while the A5 and A7 innervate the intermediate zone and the ventral horn. These conflicting results may be due to fundamental genetic differences between the rats used in our experiments (Sasco Sprague-Dawley) and those used by the other laboratory (Harlan Sprague-Dawley). This possibility was examined by determining the projections of coeruleospinal neurons in these two rat substrains using the anterograde tracer Phaseolus vulgaris leucoagglutinin. The results indicate that in Sasco rats the LC neurons project through the ipsilateral ventromedial funiculus and terminate almost exclusively in the medial part of laminae VII and VIII, the motoneuron pool of lamina IX, and lamina X. In contrast, LC neurons in Harlan rats project bilaterally through the superficial dorsal horn and the dorsolateral funiculus and terminate most heavily in dorsal horn laminae I-IV. In addition, the LC neurons of Sasco rats innervate cervical spinal cord segments more densely than lumbar spinal cord segments, while in Harlan rats the lumbar spinal cord is more densely innervated than the cervical spinal cord. These results indicate that the projections of coeruleospinal neurons in Sasco rats are fundamentally different from those in Harlan rats and suggest that noradrenergic LC neurons may have different physiological functions in these two rat substrains.

Mitogen responses of lymphocytes from lung transplant recipients--correlation with rejection and infection

Proliferative responses to nonspecific mitogens were analyzed for 119 bronchoalveolar lavages and 108 concurrent peripheral blood samples from 35 lung transplant patients. The patients were classified at each time as normal, rejecting, or infected on the basis of trans-bronchial biopsy, culture results, clinical signs, and pulmonary function. During rejection episodes the bronchoalveolar lavage responses to concanavalin A and phytohemagglutinin were significantly increased (P less than 0.004 and P less than 0.006, respectively). The differences were less pronounced when rejection occurred within 30 days after bolus immunosuppressive therapy, either as immunoprophylaxis or as treatment for a previous rejection episode, and were not significantly different from normal. Differences in response during rejection were limited to the graft; analysis of circulating T cells was not helpful (P = NS). In contrast, markedly depressed responses to Con A and PHA were seen during infection. Significant differences were observed both in the graft (P less than 0.007) and in circulating lymphocytes (P less than 0.02), suggesting that global depression of mitogen response is associated with immunocompromise. Sequential analysis of 6 patients showed that individual changes in mitogen response paralleled those seen in the population (P less than 0.046, normal vs. rejection and P less than 0.043 normal). These findings suggest that mitogen assays of bronchoalveolar lavage lymphocytes and, to a lesser extent, PBL, are clinically useful in assessing intragraft immunocompetence and in distinguishing rejection from infection in lung transplant patients.

Binding of phycoerythrin-conjugated interleukin-6 to in vitro-activated human peripheral blood mononuclear cells--effect of immunosuppressive agents and of a calcium channel blocker

We studied the effect of cyclosporine A, prednisolone, and the Ca2+ channel blocker verapamil on interleukin-6 binding to mitogen-activated peripheral blood mononuclear cells, using a flow cytometric technique and phycoerythrin-conjugated IL-6. All mitogenic stimuli up-regulated IL-6 binding to a variable degree. PHA alone or in combination with PMA was the most effective stimulant in up-regulating IL-6 binding in all the experiments performed. The main changes in IL-6 binding were seen in the large cell cluster, which consisted mainly of lymphoblasts. PHA and PHA/PMA, however, also up-regulated the mean fluorescence intensity on the small cell cluster, which consisted mainly of quiescent lymphocytes. The overall effect of the three pharmacological agents on mitogen-up-regulated IL-6 binding was minimal; most significant were a down-regulation by all three agents of IL-6 binding by small lymphocytes in PHA/PMA cultures, a down-regulation of IL-6 binding by CsA in PHA/PMA-induced large PBMC, and an up-regulation by verapamil of PMA-induced IL-6 binding in large PBMC. Measurements of IL-2 binding and of IL-6 production in the same cultures showed a different pattern than that seen with IL-6 binding, as well as different CsA, prednisolone, and verapamil action. In conclusion, by using a new flow cytometric technique providing information both about the quantity of bound cytokine and about the proportion of IL-6-binding cells, we have demonstrated that IL-6 receptor expression in vitro by PBMC can be up-regulated by the use of stimulants differing in the signal transduction pathways they activate. In addition, by using different pharmacological agents and stimuli to dissect different activation pathways of the in vitro immune response, we conclude that IL-6R generation is regulated differently from IL-6 production. Furthermore, since CsA and prednisolone are known inhibitors of in vitro IL-2 production, our results indicate that IL-6R generation does not rely exclusively on the presence of IL-2.

Mitogen-induced human T cell proliferation is associated with increased expression of selected PKC genes

The induction of T cell proliferation and differentiation into mature effector cells is dependent on two principal exogenous signals that are provided by the antigen or mitogen and IL2. The enzyme protein kinase C (PKC) has a major role in the antigen-receptor signalling pathway in T cells, but appears not to be involved in signalling via the IL2-receptor (IL2-R). Since both pathways trigger a series of sequentially coordinated transcriptional events in which numerous genes are activated, we tested whether a T cell mitogen acting via the TCR/CD3 complex, and IL2, affect the expression of the conventional, Ca(2+)-dependent, PKC genes (alpha, beta and gamma) in T cells. Stimulation of human peripheral blood lymphocytes or an enriched population of human T cells with phytohemagglutinin resulted in augmented mRNA levels of PKC alpha and PKC beta, but not PKC gamma-gene. The response peaked at 24-48 hr when a 3-5-fold increase was observed. Stimulation of IL2-R alpha-expressing T cells with human recombinant IL2 induced cell proliferation and transcription of the IL2-R alpha gene (greater than 100-fold), but did not change mRNA levels of PKC alpha or PKC beta genes. The results suggest that stimulation of human T cells with mitogens acting via the TCR/CD3 complex, that involve activation of PKC, is accompanied also by a late activation of selected PKC genes. By contrast, agonists such as IL2, that operate via a different signalling pathway, do not modify the expression of any of the known conventional PKC genes.

Non-transferrin dependent 59Fe uptake in phytohemagglutinin-stimulated human peripheral lymphocytes

Human peripheral lymphocytes stimulated by phytohemagglutinin (PHA) have been used to demonstrate the characteristics of iron uptake from non-transferrin iron donors. When incubated with 59Fe(II)-ascorbate or 59Fe(III)-nitrilotriacetate (Fe-NTA), stimulated lymphocytes (2 micrograms/ml PHA) showed a tenfold increase in uptake of 59Fe as compared with the resting cells. The uptake of 59Fe from these iron donors was time and concentration dependent, showed saturation kinetics, and was not influenced by the addition of a tenfold excess of unlabeled Fe(III)2-transferrin (Fe-Tf). The amount of 59Fe accumulated from 59Fe-NTA was about one-third of that from 59Fe2-Tf, whereas the uptake of 59Fe from 59Fe-ascorbate was about tenfold higher. When stimulated with varying doses of PHA, lymphocytes showed maximal uptake of 59Fe from 59Fe2-Tf at the concentration of PHA (1 microgram/ml) optimal for 3H-thymidine incorporation. Lymphocytes stimulated with supraoptimal concentrations (5-20 micrograms/ml) of PHA showed slightly less iron uptake from 59Fe-Tf and had a longer transferrin cycle time, as compared with the cells under optimal stimulation. In contrast, the uptake of 59Fe from non-transferrin 59Fe donors in cells stimulated with 5-20 micrograms/ml PHA was greater than that in cells grown with 1 or 2 micrograms/ml PHA. It is suggested that lymphocytes take up iron from non-transferrin iron donors by processes different from the iron uptake pathway used by transferrin.

Anaphylactic shock after skin test with phytohaemoagglutinin

A young woman (26 years old), with gastrointestinal candidosis of 8 months duration, was hospitalized in our department to study her cell immunity. Five minutes after an id injection of PHA (bactophytohaemoagglutinin M, Difco, 1 mg), mix monilieae, mix tricophyton and PPD Berna, she showed an extensive wheal and flare reaction in the PHA injection area, eyelid oedema and respiratory distress. In spite of adrenaline, corticosteroid and antihistamine drug administration, the patient collapsed and was admitted to the resuscitation department, where she quickly recovered. In the following days, the patient underwent immune and allergy testing: 1) total Ige immuno-enzymatic assay: 72 KU/1; 2) specific IgE and IgE immuno-enzymatic assay for Candida: negative; 3) in vitro lymphocyte transformation test (thymidine 2-C14) with PHA Difco was positive. This finding and the positivity of the id injection with PHA could indicate an allergic type I immunoreaction, the description of which we have not found in the international literature (the presence of IgG STS cannot be totally excluded).

A study on delayed hypersensitivity to rotavirus in infancy and childhood

The T-cell responsiveness to rotavirus antigen and phytohaemagglutinin (PHA) together with T-cell total and subsets quantitation was carried out in 50 non-diarrhoeal and six rotavirus diarrhoeal subjects. All individuals in the non-diarrhoeal group responded well to PHA and had normal values for T-cell subsets. The number of positive responders to the rotavirus antigen increased gradually from 0% in the newborns to 92% in older children. The increasing risk of exposure to rotavirus infection is thought to be a chief cause of this age-related variation. All the rotavirus diarrhoeal patients responded well to the rotavirus antigen, indicating a potent test system. The T-cell responses to PHA and the T-cell subsets were significantly low. This could be due to temporary T-cell suppression that may accompany viral infection. Our results are discussed in the context of previous studies.

A direct projection from the medial vestibular nucleus to the cervical spinal dorsal horn of the rat, as demonstrated by anterograde and retrograde tracing

Phaseolus vulgaris leucoagglutinin and wheat germ agglutinin-horseradish peroxidase were iontophoretically injected into different parts of the vestibular nuclear complex (VNC) of the rat. Injections centered into the caudal part of the medial vestibular nucleus revealed a vestibulospinal projection predominantly to the dorsal horn of the cervical spinal cord, besides the expected projection to the intermediate zone (IZ) and ventral horn (VH). While most of the anterogradely labelled fibres could be localized in laminae III to V, some scattered fibres were also seen in laminae I and VI. Lamina II remained free of labelling. The dorsal horn (DH) area with detectable anterograde labelling showed a rostrocaudal extension from C1-C6. Injections into other parts of the VNC labelled fibres and terminals in the IZ and VH while the DH remained almost free of labelling. Additionally, fluorogold and wheat germ agglutinin-horseradish peroxidase were pressure- or iontophoretically injected at different levels into the spinal cord to confirm the projection to the dorsal horn by means of retrograde tracing. Labelled neurons in the area of the medial vestibular nucleus (MVN), from which anterograde labelling in the DH was obtained, were only detectable after fluorogold and wheat germ agglutinin-horseradish peroxidase injections into the cervical spinal cord, in particular its DH. This projection from the caudal medial vestibular nucleus to the dorsal horn of the cervical spinal cord probably enables the VNC to influence sensory processing in the DH, in addition to its well-established influence on posture and locomotion via projections to the intermediate zone and ventral horn.

The facilitated effect of retinol on rat hepatocarcinogenesis induced by 3'-methyl-4-dimethylaminoazobenzene

To examine the influence of retinol acetate (retinol, known as an inhibitor of tumor promotion) on 3'-methyl-4-dimethyl-aminoazobenzene (3'MeDAB)-induced hepatocarcinogenesis, rats were fed with a diet containing 0.06% 3'MeDAB for 4 or 7 weeks and then with a normal diet for 21 or 18 weeks. Rats were given retinol (0, 6.25, 12.5 and 25.0 mg/rat, dissolved in DMSO) i.p. every 5 days from the 10th week to the 20th week. As a control, rats were fed a basal diet and given retinol at the same doses as mentioned above. At the 25th week, the incidence of hepatoma (hepatocellular carcinoma and cholangiocarcinoma) of each group was checked. In rats fed diet containing 3'MeDAB for 7 weeks, significant increases in the incidence of hepatoma were seen in retinol-treated groups at various doses. In rats fed 3'MeDAB diet for 4 weeks, all three doses also moderately, though not significantly, increased the incidence of hepatoma. No liver tumor was found in rats fed normal diet followed by treatment with retinol at any dose. Except for slight but detectable elevation of cellular retinoic acid binding protein levels in tumor tissues obtained from rats treated with retinol, no obvious differences in cellular retinol binding protein and gamma-glutamyl transpeptidase in the tumor tissues were observed between retinol-treated and untreated rats. Phytohemagglutinin-induced lymphocyte blastogenesis of the tumor-bearing rats with or without retinol treatment showed approximately 50% inhibition compared with that of rats fed normal diet without retinol treatment. These results indicated that the administration of retinol in the early stages of hepatocarcinogenesis enhanced the tumor induction, possibly due to the fixation of malignant transformation of the cells.

Hexadecylphosphocholine-mediated enhancement of T-cell responses to interleukin 2

The effect of low-dose hexadecylphosphocholine (He-PC) on normal peripheral mononuclear cells (PMNC) was studied. Interferon-gamma (IFN-g) production, interleukin 2 (IL-2) receptor, and HLA-DR antigen expression were investigated, representing typical T-cell activation parameters. In PMNC cultures, He-PC dose-dependently enhanced the production of IFN-g, provided IL-2 had been added exogenously. Without IL-2 He-PC was ineffective. In some cultures, at a concentration of 8 micrograms/ml He-PC stimulated the secretion of IFN-g more than 20-fold compared to untreated controls. Although He-PC by itself lacked mitogenic activity, this compound also stimulated IFN-g production in the presence of suboptimal doses of phytohemagglutinin (PHA). Immunofluorescence studies demonstrated that He-PC also increased IL-2 receptor and HLA-DR antigen expression under these experimental conditions. Taken together, these results indicate that He-PC may possess immunomodulatory activity also in vivo, acting as a costimulator for the IL-2-mediated T-cell activation process.

Effect of (dl)-5-methyltetrahydrofolate on acute non-lymphocytic leukemia cells in primary culture

High doses of (dl)-5-methyltetrahydrofolate (mTHF) cause strong inhibition of growth of leukemic cell lines. We studied the effect of mTHF, at concentrations ranging from 10(-3) M to 10(-4) M, on peripheral leukemic cells obtained from 15 acute non-lymphocytic leukemia (ANLL) patients, by [3H]-thydimidine uptake inhibition. Unlike leukemic cell lines, mTHF exerts a variable effect on ANLL cells in primary culture. While about 33% of cases are strongly inhibited, 55% are only slightly affected, showing a reduction in growth comparable to normal cell populations tested (unstimulated and PHA-stimulated lymphocytes, day 7 and day 14 colony forming units-granulocyte/monocyte (CFU-GM), normal blast colonies). In a minority of cases we observed stimulation of growth. This study reflects the metabolic variability of single-case leukemic cell populations, possibly in relationship to folate transport and accumulation.

Some cutaneous responses to mitogen injection in sheep, with special reference to eosinophil leucocytes

Research in laboratory animals suggests that eosinophil numbers in some cutaneous reactions may reveal inherent differences in resistance to parasite infection. An intradermal injection with 10 microgram of the mitogen phytohaemagglutinin, followed by counting eosinophils in the deep dermis of skin biopsies removed 24 hours later, appears to be a practical and reproducible way of comparing the ability of individual sheep to marshal eosinophils in a tissue. This procedure will allow study of the relationship between eosinophil response and resistance to parasite infection in sheep.

Evaluation of lymphocyte activation by flow cytometric determination of interleukin-2 (CD25) receptor

Lymphocyte response to mitogens is a habitually-used test in the evaluation of the immune system. The usual method with [3H]thymidine yields results which are difficult to interpret. In our search for an alternative, we examined the feasibility of determining T lymphocyte activation by measuring interleukin-2 receptor (CD25) expression with flow cytometry. We found a good correlation between CD25 molecule expression and the dose of phytohemagglutinin, however, there was no correlation between disintegrations per minute produced by [3H]thymidine uptake and the percentage of CD25 expressed by cells.