T-cell Blastogenesis Research Articles

Trajectories of Stress, Depressive Symptoms, and Immunity in Cancer Survivors: Diagnosis to 5 Years.

Five-year disease endpoint trajectories are available for every cancer site. In contrast, there are few longitudinal, biobehavioral studies of survivors extending beyond the first or second year following diagnosis. This gap is addressed with stress, depressive symptom, and immunity data from breast cancer patients followed continuously for 5 years. Women (N = 113) diagnosed and surgically treated for breast cancer and awaiting adjuvant therapy completed self-report measures of stress and depressive symptoms and provided blood for immune assays [natural killer cell cytotoxicity (NKCC) and T-cell blastogenesis]. Assessments (N = 12) were repeated every 4 to 6 months for 5 years. Multiphase linear mixed models show phases of change and identified specific time points of change. Cancer stress shows two distinct phases of decline, with the change point being 12 months. In contrast, a steep decline in depressive symptoms occurs by 7 months, with stable, low levels thereafter. NKCC shows a steady upward trajectory through 18 months and upper limit stability thereafter, whereas there was no reliable trajectory for T-cell blastogenesis. For the first time, trajectories and specific time points of change in biobehavioral data for breast cancer survivors are provided, traced through 5 years. Following diagnosis, the breast survivor experience is one of a co-occurrence of change (recovery) in psychologic and innate immunity markers from diagnosis to18 months, and a pattern of stability (depression, NKCC) or continued improvement (stress) through year 5. These data provide new directions for survivorship care and detail of the biobehavioral trajectory. Clin Cancer Res; 23(1); 52-61. ©2016 AACR.

Mitogenic Activation and Proliferation of T Lymphocytes in TRPM7 Kinase-Dead Mutant Mice

Calcium and magnesium ions have been implicated in T lymphocyte proliferation in response to antigen recognition. Specifically, it is believed that calcium and magnesium elevations in the cytoplasm are necessary for efficient T cell proliferation. Research over the past two decades has focused on identifying the plasma membrane ion channels responsible for governing Ca2+ influx in lymphocytes and Orai-STIM, Kv1.3 and KCa3.1 channels were shown to be crucial for persistent calcium mobilization. Pharmacologic or genetic suppression of calcium influx gives rise to lymphoproliferative defects. In addition to Ca2+, several studies have demonstrated that Mg2+ influx positively regulates proliferation. TRPM7 is a channel-kinase highly expressed in T cells and reported to conduct both Ca2+ and Mg2+. TRPM7 channels give rise to outwardly rectifying currents inhibited by cytosolic Mg2+. TRPM7 protein appears to be necessary for murine thymocyte development, while small reductions in splenic T lymphocyte numbers were observed in TRPM7-deleted mice. Deletion of TRPM7 in a chicken B cell line resulted in severe proliferation defects. In this work we examine the role of TRPM7 kinase in T-cell blastogenesis and proliferation using a recently reported kinase-dead mutant mouse (Kaitsuka et al, Sci. Rep. 2014). Our goal was to compare the effects of extracellular Ca2+/Mg2+ between wildtype and kinase-dead mutant mouse splenic T cells stimulated with PMA/ionomycin. Increasing Ca2+ or Mg2+ stimulated proliferation in both wildtype and kinase-dead mouse lymphocytes but with significant differences. Using a Coulter counter we also measured the diameters of resting and activated T cells in response to changes in external Ca2+/Mg2+. The differences between WT and mutant T cell blastogenesis and proliferation parameters are discussed in the context of controversies regarding the role of TRPM7 channel and kinase function in cellular Mg2+ homeostasis.

Investigation of 5-HT2A gene expression in PBMCs of patients with allergic asthma.

Asthma is an inflammatory airway disorder in which different immune cells in the blood and lungs play a fundamental role. In asthma condition, the airway inflammation accompanied by bronchial smooth muscle spasm cause airway obstruction. A study showed that high concentration of blood serotonin is associated with the intensity and exacerbation of asthma disease. Other studies showed that a subtype of serotonin receptor called 5-Hydroxytriptamine 2A receptor (5- HT2A) can enhance T-cell blastogenesis and production of pro-inflammatory cytokines such as IFNγ. The objective of this study was to assess the level of 5-HT2A in peripheral blood mononuclear cells (PBMCs) of asthmatic patients. PBMCs were extracted from blood of 30 patients with asthma and 30 normal people. After synthesizing cDNAs from total mRNAs, real-time PCR was performed to amplify 5-HT2A and β-actin (as an internal control). The expression ratios were analyzed in patients with asthma in comparison with normal group. The results indicated that gene expression is significantly increased in peripheral blood mononuclear cells (PBMCs) of asthma patients in comparison with normal group (P = 0.003). The results of this study can suggest designing a protocol by using of the 5-HT2A receptor expression in PBMCs as a biomarker of asthma, but this requires further studies on a larger number of patients. In addition, the potential role of this receptor in bronchoconstriction can lead us to use its antagonists as a new treatment in asthma.

Phenolic-glycolipid-1 and lipoarabinomannan preferentially modulate TCR- and CD28-triggered proximal biochemical events, leading to T-cell unresponsiveness in mycobacterial diseases

BackgroundAdvanced stages of leprosy show T cell unresponsiveness and lipids of mycobacterial origin are speculated to modulate immune responses in these patients. Present study elucidates the role of phenolicglycolipid (PGL-1) and Mannose-capped lipoarabinomannan (Man-LAM) on TCR- and TCR/CD28- mediated signalling.ResultsWe observed that lipid antigens significantly inhibit proximal early signalling events like Zap-70 phosphorylation and calcium mobilization. Interestingly, these antigens preferentially curtailed TCR-triggered early downstream signalling events like p38 phosphorylation whereas potentiated that of Erk1/2. Further, at later stages inhibition of NFAT binding, IL-2 message, CD25 expression and T-cell blastogenesis by PGL-1 and Man-LAM was noted.ConclusionAltogether, we report that Man-LAM and PGL-1 preferentially interfere with TCR/CD28-triggered upstream cell signalling events, leading to reduced IL-2 secretion and T-cell blastogenesis which potentially could lead to immunosupression and thus, disease exacerbation, as noted in disease spectrum.

Impact of breast cancer recurrence and cancer-specific stress on spouse health and immune function

Spouses of cancer patients are at-risk for poor psychological and physical health as they cope with the complex nature of the disease and fears of losing their partner. Moreover, spouses often serve as patients' primary informal caregivers, a group that evidences poor outcomes across a variety of domains. The present study examines the relative contributions of cancer recurrence - a cancer-specific stressful event - and the subjective experience of cancer-specific stress (IES) in a sample of male spouses of breast cancer survivors. We hypothesized that stress would contribute to poorer physical health and compromised immune function. Spouses (recurrence; n=16) of patients who were coping with their first recurrence were matched to spouses of patients with no evidence of disease (disease-free; n=16). Self-reported physical health (physical symptoms and fatigue) and immune function [T-cell blastogenic response to the mitogens Concanavalin A (ConA) and phytohemagglutanin (PHA) and T3 monoclonal antibody (T3 Mab)] were included as outcomes. Results indicated that patient recurrence status was not a significant unique predictor of physical health or immune function; rather, among all spouses, cancer-specific stress symptoms were associated with increased physical symptoms and altered T-cell blastogenesis. These data suggest that the health implications of caregiving for spouses of cancer survivors is more strongly linked to their subjective experience of cancer as stressful, rather than simply the patients' disease status.

Zizyphus lotus L. (Desf.) modulates antioxidant activity and human T-cell proliferation

BackgroundZizyphus lotus L. (Desf.) also known as Jujube, is a deciduous shrub which belongs to Rhamnaceae family. This plant is used in Algerian traditional medicine for its anti-diabetic, sedative, analgesic, anti-inflammatory and hypoglycaemic activities. In the present study, we determined the concentrations of different vitamins (vitamin A, C and E) and fatty acids in root, stem, leaves, fruit pulp and seed of Zizyphus lotus L. (Desf.) and assessed the effects of their aqueous extracts on antioxidant status and human T-cell proliferation.MethodsAqueous filtrates from different parts, i.e, root, leaf, stem, fruit pulp and seed, of Zizyphus lotus L. (Desf.) were prepared. Vitamin C levels were determined by precipitating with 10% trichloroacetic acid and vitamin A and E were assessed by HPLC. Lipid composition of these extracts was determined by gas-liquid chromatography. Anti-oxidant capacity was evaluated by using anti-radical resistance kit [Kit Radicaux Libres (KRL@; Kirial International SA, Couternon, France)]. T-cell blastogenesis was assessed by the incorporation of 3H-thymidine. IL-2 gene expression was evaluated by RT-qPCR.ResultsOur results show that fruit pulp contained higher vitamin A and C contents than other parts of the plant. Furthermore, the fruit pulp was the richest source of linoleic acid (18:2n-6), a precursor of n-6 fatty acids. Fruit seeds possessed higher vitamin C levels than leaves, roots and stem. The leaves were the richest source of vitamin E and linolenic acid (18:3n-3), a precursor of n-3 fatty acids. The antioxidant capacity of the different extracts, measured by KRL@ test, was as follows: pulp < seed<leaf<root < stem. As far as T-cell proliferation is concerned, we observed that the different extracts of Zizyphus lotus L. (Desf.) exerted immunosuppressive effects.ConclusionSeed extracts exerted the most potent immunosuppressive effects on T cell proliferation and IL-2 mRNA expression. The results of the present study are discussed in the light of their use to modulate the immune-mediated diseases.

Mycobacterial antigen(s) induce anergy by altering TCR- and TCR/CD28-induced signalling events: Insights into T-cell unresponsiveness in leprosy

Present study investigates the role of Mycobacterium leprae (M. leprae) antigens on TCR- and TCR/CD28-induced signalling leading to T-cell activation and further correlates these early biochemical events with T-cell anergy, as prevailed in advanced stages of leprosy. We observed that both whole cell lystae (WCL) and soluble fraction of M. leprae sonicate (MLSA) not only inhibited TCR, thapsigargin and ionomycin induced calcium fluxes by diminishing the opening of calcium channels, but also TCR- or TCR/CD28-induced proximal signalling events like phosphorylation of Zap-70 and protein kinase-C (PKC) activity. Study of TCR- and TCR/CD28-induced downstream signals revealed that M. leprae antigens curtail phosphorylation of both Erk1/2 and p38MAPK, consequently altering terminal signalling events like reduced binding of NFAT on IL-2 promoter and transcription of IL-2 gene, diminished expression of activation markers (CD25 and CD69). Furthermore, M. leprae fractions significantly inhibited IL-2 secretion and T-cell blastogenesis in healthy individuals. Altogether, results suggest that M. leprae interferes with TCR/CD28-induced upstream as well as downstream signalling events resulting in reduced IL-2 production and thus inhibition in T-cell proliferation, which might be responsible for T-cell unresponsiveness leading to stage of immunosuppression and consequently, for the progression of disease.

Vitamin A status is associated with T-cell responses in Bangladeshi men

Recommendations for vitamin A intake are based on maintaining liver stores of > or = 0.070 micromol/g, which is sufficient to maintain normal vision. We propose that higher levels may be required to maintain normal immune function. To test this hypothesis, we conducted an 8-week residential study among thirty-six healthy Bangladeshi men with low vitamin A stores. Subjects were randomised to receive vitamin A (240 mg in four doses) or placebo during study weeks 2 and 3. Vitamin A stores were estimated by isotopic dilution at week 8. Total T-cells, the naive T-cells:memory T-cells ratio and mitogen-induced lymphocyte proliferation were positively and significantly correlated with vitamin A stores (P < 0.05). Mitogen-stimulated IL-2, IL-4 and TNFalpha increased significantly (P < 0.05) in the vitamin A but not placebo group after supplementation, while IL-10 production was significantly and negatively correlated with vitamin A stores (P < 0.05). Segmented linear regression analysis revealed that naive T-cell counts and T-cell blastogenesis were positively associated with vitamin A stores above but not below 0.070 mumol/g liver. These data show that increasing vitamin A stores above the level that maintains normal vision enhances some measures of T-cell-mediated immunity, suggesting a difference in requirements for maintaining vision and immune function.

Distress reduction from a psychological intervention contributes to improved health for cancer patients

Purpose. Psychological interventions are efficacious in reducing emotional distress for cancer patients. However, it is not clear whether psychological improvements are, in turn, related to improved health. A clinical trial tests whether a psychological intervention for cancer patients can do so, and also tests two routes to achieve better health: (a) reducing patients’ Emotional Distress, and/or (b) enhancing their functional immunity. Methods. Post-surgery, 227 breast cancer patients were randomized to intervention or assessment only Study Arms. Conducted in small groups, intervention sessions were offered weekly for 4 months and followed by monthly sessions for 8 months. Measures included psychological (distress), biological (immune), and health outcomes (performance status and evaluations of patient’s symptomatology, including toxicity from cancer treatment, lab values) collected at baseline, 4 months, and 12 months. Results. A path model revealed that intervention participation directly improved health ( p < .05) at 12 months. These effects remained when statistically controlling for baseline levels of distress, immunity, and health as well as sociodemographic, disease, and cancer treatment variables. Regarding the mechanisms for achieving better health, support was found for an indirect effect of distress reduction. That is, by specifically lowering intervention patients’ distress at 4 months, their health was improved at 12 months ( p < .05). Although the intervention simultaneously improved patients’ T-cell blastogenesis in response to phytohemagglutinin (PHA), the latter increases were unrelated to improved health. Conclusion. A convergence of biobehavioral effects and health improvements were observed. Behavioral change, rather than immunity change, was influential in achieving lower levels of symptomatology and higher functional status. Distress reduction is highlighted as an important mechanism by which health can be improved.

Novel Leptin Receptor Mutation in NOD/LtJ Mice Suppresses Type 1 Diabetes Progression

Recently, we identified in normally type 1 diabetes-prone NOD/LtJ mice a spontaneous new leptin receptor (LEPR) mutation (designated Lepr(db-5J)) producing juvenile obesity, hyperglycemia, hyperinsulinemia, and hyperleptinemia. This early type 2 diabetes syndrome suppressed intra-islet insulitis and permitted spontaneous diabetes remission. No significant differences in plasma corticosterone, splenic CD4(+) or CD8(+) T-cell percentages, or functions of CD3(+) T-cells in vitro distinguished NOD wild-type from mutant mice. Yet splenocytes from hyperglycemic mutant donors failed to transfer type 1 diabetes into NOD.Rag1(-/-) recipients over a 13-week period, whereas wild-type donor cells did so. This correlated with significantly reduced (P < 0.01) frequencies of insulin and islet-specific glucose-6-phosphatase catalytic subunit-related protein-reactive CD8(+) T-effector clonotypes in mutant mice. Intra-islet insulitis was also significantly suppressed in lethally irradiated NOD-Lepr(db-5J)/Lt recipients reconstituted with wild-type bone marrow (P < 0.001). In contrast, type 1 diabetes eventually developed when mutant marrow was transplanted into irradiated wild-type recipients. Mitogen-induced T-cell blastogenesis was significantly suppressed when splenic T-cells from both NOD/Lt and NOD-Lepr(db-5J)/Lt donors were incubated with irradiated mutant peritoneal exudate cells (P < 0.005). In conclusion, metabolic disturbances elicited by a type 2 diabetes syndrome (insulin and/or leptin resistance, but not hypercorticism) appear to suppress type 1 diabetes development in NOD-Lepr(db-5J)/Lt by inhibiting activation of T-effector cells.

N‐3 Fatty Acids Modulate T‐Cell Calcium Signaling in Obese Macrosomic Rats

We investigated the effects of a diet containing EPAX-7010, rich in PUFAs such as eicosapentaenoic acid [20:5(n-3)] and docosahexaenoic acid [22:6(n-3)], i.e., a PUFA/EPAX regimen, on T-cell activation in diabetic pregnant rats and their obese pups. Mild hyperglycemia in pregnant rats was induced by intraperitoneal injection of streptozotocin on Day 5 of gestation. T-cell blastogenesis was assayed by using (3)H-thymidine, whereas intracellular free calcium concentrations ([Ca(2+)]i) were measured by using Fura-2 in diabetic pregnant rats and their obese offspring. Concavalin-A-stimulated T-cell proliferation was decreased in both pregnant diabetic rats and their obese pups as compared with control animals. Feeding the PUFA/EPAX diet restored T-cell proliferation in both groups of animals. We also employed ionomycin, which at 50 nM opens calcium channels, and thapsigargin (TG), which recruits [Ca(2+)]i from endoplasmic reticulum pool. We observed that ionomycin-induced increases in [Ca(2+)]i in T-cells of diabetic mothers and obese offspring were greater than in those of control rats. Furthermore, feeding PUFA/EPAX diet diminished significantly the ionomycin-evoked rise in [Ca(2+)]i in diabetic and obese animals. TG-induced increases in [Ca(2+)]i in T-cells of diabetic pregnant rats and their obese offspring were greater than in those of control rats. The feeding of the experimental diet significantly curtailed the TG-evoked increases in [Ca(2+)]i in both diabetic and obese rats. Together, these observations provide evidence that T-cell activation and T-cell calcium signaling are altered during gestational diabetes and macrosomia. Hence, dietary fish oils, particularly eicosapentaenoic acid and docosahexaenoic acid, may restore these T-cell abnormalities.

Cellular immunity in breast cancer patients completing taxane treatment.

A field study of postchemotherapy immune functioning relative to the use of taxanes is reported. Immune responses in breast cancer patients were analyzed as a function of whether patients received taxane as part of their adjuvant chemotherapy. Immune levels of 227 stage II/III breast cancer patients were measured immediately after surgery prior to chemotherapy and again 12 months later when all chemotherapies had been completed. T-cell blastogenesis and natural killer (NK) cell lysis levels of patients receiving taxanes (n = 55) were compared with levels of patients not receiving taxanes (n = 172). Regression analyses were conducted. The administration of taxane as part of combination chemotherapy predicted increased T-cell blastogenesis and NK cell cytotoxicity after the conclusion of all chemotherapies. For the Taxane group, average phytohemagglutinin-induced blastogenesis was 37% higher and NK cell cytotoxicity was 39% higher than the values for the No-Taxane group. Data from group comparisons with appropriate controls in a sizable clinical sample contravene traditional wisdom that taxanes suppress patients' immune cell functions. Problems in generalizing direct-contact laboratory models to the field of cancer treatment are highlighted.

Modulation of intracellular calcium concentrations and T cell activation by prickly pear polyphenols.

Opuntia ficus indica (prickly pear) polyphenolic compounds (OFPC) triggered an increase in [Ca2+]i in human Jurkat T-cell lines. Furthermore, OFPC-induced rise in [Ca2+]i was significantly curtailed in calcium-free buffer (0% Ca2+) as compared to that in 100% Ca2+ medium. Preincubation of cells with tyrphostin A9, an inhibitor of Ca2+ release-activated Ca2+ (CRAC) channels, significantly diminished the OFPC-induced sustained response on the increases in [Ca2+]i. Lanthanum and nifedipine, the respective inhibitors of voltage-dependent and L-type calcium channels, failed to curtail significantly the OFPC-induced calcium response. As OFPC still stimulated increases in [Ca2+]i in 0% Ca2+ medium, the role of intracellular calcium was investigated. Hence, addition of thapsigargin (TG), an inhibitor of Ca2+-ATPase of the endoplasmic reticulum (ER), during the OFPC-induced peak response exerted an additive effect, indicating that the mechanism of action of these two agents are different. Furthermore, U73122, an inhibitor of IP3 production, completely abolished increases in [Ca2+]i, induced by OFPC, suggesting that these polyphenols induce the production of IP3 that recruits calcium from ER pool. Polyphenolic compounds do act extracellularly as addition of fatty acid-free bovine serum albumin (BSA) significantly diminished the rise in [Ca2+]i evoked by the formers. OFPC also induced plasma membrane hyperpolarisation which was reversed by addition of BSA. OFPC were found to curtail the expression of IL-2 mRNA and T-cell blastogenesis. Together these results suggest that OFPC induce increases in [Ca2+]i via ER pool and opening of CRAC channels, and exert immunosuppressive effects in Jurkat T-cells.

Ionotrophic 5-hydroxytryptamine type 3 receptor activates the protein kinase C-dependent phospholipase D pathway in human T-cells

The present study was undertaken to investigate the role of the 5-hydroxytryptamine (5-HT) ionotrophic receptor 5-HT(3) in the activation of human Jurkat T-cells. 5-HT and 2-methyl-5-HT (2Me-5-HT), an agonist of the 5-HT(3) receptor, induced increases in intracellular free Na(+) concentrations, [Na(+)](i), via opening of the ionotrophic receptor in these cells. These two serotonergic (5-hydroxytryptaminergic) agents potentiated phytohaemagglutinin (PHA)-induced T-cell activation. However, they failed to potentiate dioctanoglycerol-plus-ionomycin-stimulated T-cell blastogenesis. Interestingly, an inhibitor of protein kinase C (PKC), GF 109203X, curtailed significantly 5-HT and 2Me-5-HT-potentiated T-cell activation. These results demonstrate that the opening of the 5-HT(3) ionotrophic receptor is implicated in T-cell activation via the PKC pathway. Furthermore, 5-HT and 2Me-5-HT stimulated phospholipase D (PLD) activity, as measured by the production of phosphatidylethanol and phosphatidylbutanol at the expense of phosphatidic acid (PA). GF 109203X significantly curtailed the 5-HT- and 2Me-5-HT-induced PLD activity and T-cell activation. The PLD/PA pathway stimulated by these two serotonergic agents resulted in the production of 1,2-diacylglycerol (DAG) mass in Jurkat T-cells. These results altogether suggest that 5-HT and 2Me-5-HT potentiate T-cell activation via increases in [Na(+)](i) and the activation of the PKC-dependent PLD pathway.

Cross-modulation by transforming growth factor beta in human tuberculosis: suppression of antigen-driven blastogenesis and interferon gamma production.

In tuberculosis, Mycobacterium tuberculosis (MTB)-stimulated T-cell responses are depressed transiently, whereas antibody levels are increased. Lymphoproliferative responses of peripheral blood mononuclear cells (PBMCs) from Pakistani tuberculosis (TB) patients to both mycobacterial and candidal antigens were suppressed by approximately 50% when compared to healthy purified protein derivative (PPD)-positive household contacts. Production of interferon gamma (IFN-gamma) in response to PPD also was depressed by 78%. Stimulation with PPD and the 30-kDa alpha antigen of MTB (30-kDa antigen) induced greater secretion of transforming growth factor beta (TGF-beta), but not interleukin 10 (IL-10) or tumor necrosis factor alpha (TNF-alpha), by PBMCs from TB patients compared to healthy contacts. The degree of suppression correlated with the duration of treatment; patients treated for <1 month had significantly lower T-cell blastogenesis and IFN-gamma production and higher levels of TGF-beta than did patients treated for >1 month. Neutralizing antibody to TGF-beta normalized lymphocyte proliferation in response to PPD, partially restored blastogenesis to candidal antigen, and significantly increased PPD-stimulated production of IFN-gamma in TB patients but not in contacts. Neutralizing antibody to IL-10 augmented, but did not normalize, T-cell responses to both PPD and candida in TB patients and candidal antigen in contacts. TGF-beta, produced in response to MTB antigens, therefore plays a prominent role in down-regulating potentially protective host effector mechanisms and looms as an important mediator of immunosuppression in TB.

The cytotoxicity of macrocyclic trichothecenes, roridin A and verrucarin A, on murine T-cells is reduced by Ia-negative splenic adherent cells

The in vitro effect of macrocyclic trichothecenes, roridin A and verrucarin A, and a non-macrocyclic trichothecene, T-2 toxin, on the concanavalin A-induced murine T-cell blastogenesis was investigated. The macrocyclic trichothecenes inhibited the blastogenesis of both thymocytes and splenocytes, splenocytes being more resistant than thymocytes. Such resistance to macrocyclic trichothecenes was not observed in splenic T-cells separated from the other cell population, nor in splenocytes depleted of adherent cells. In order to find the cell population responsible for resistance, the toxins were incubated with fractionated splenic cells and then cytotoxicity of the supernatants of the incubation mixtures was examined by using T-cell blastogenesis assay. The results showed that the splenocytes depleted of Ia-negative cells had the ability to reduce the cytotoxicity of the macrocyclic trichothecenes, but not that of T-2.

Temporal analysis of human leucocyte surface antigen expression and neutrophil respiratory burst activity after thermal injury

Sepsis, the major cause of morlidity and mortality after burn injury, is related to multiple immune derangements. Using monoclonal antibodies and two-colour flow cytometry to identify surface antigens, peripheral blood mononuclear cell (PBMC) populations were analysed and correlated with lymphocyte proliferation assays for 21 days postinjury. In addition, in vitro expression of activation antigens by mitogen-stimulated PBMCs was analysed during the time period. Twenty-nine burn patients were studied, with burn injuries ranging from 19 to 97 per cent TBSA; PBMCs from human volunteers were used for control cells. Patients received aggressive enteral nutritional support starting on day 1 postburn and underwent early excision and grafting of wounds; no patients developed sepsis during the study period. The most consistent changes in PBMCs after thermal injury were decreased percentages of total T cells (CD3 +), T helper/inducer cells (CD4 +), and T suppressor/cytotoxic cells (CD8 +); the percentages of natural killer (CD16 + ) cells were not altered. Expression of surface ‘activation’ antigens on CD4 + and CD8 + cells (HLA-DR, interleukin-2 receptor and transferrin receptor) after mitogen stimulation was significantly depressed as early as 1 day postburn. An early monocytosis was seen on day 1 postburn, but decreases were found on days 4 and 7. Monocyte expression of HLA-DR antigen was suppressed throughout the study. Lymphocyte proliferation after mitogen stimulation and the responses of lymphocytes in mixed lymphocyte culture were suppressed postburn. Neutrophil respiratory burst responses were supranormal on days 1 and 7 postburn, but the differences were not statistically significant. Although burn morbidity and mortality are primarily due to bacterial organisms, defects in T-cell and monocyte immune functions are more predominant than defects in neutrophil bactericidal function in these patients. The block in T-cell blastogenesis is early in the cell cycle, prior to DNA synthesis.

Regulation of murine T-lymphocyte function by spleen cell-derived and exogenous serotonin.

The modulatory effects of serotonin on T-cell activity were investigated. T-cell blastogenesis of normal spleen cells was slightly stimulated by the addition of low doses (1 and 10 ng/ml) of the inducer of serotonin release, fenfluramine. In contrast to the stimulatory effects of low doses of fenfluramine, high doses of fenfluramine (1 and 10 ug/ml) or of exogenously added serotonin (> or = 0.1 ug/ml) inhibited T-cell activation. Both the stimulation by low dose fenfluramine and the inhibition by high dose fenfluramine were accentuated by pretreating mice with tryptophan to heighten intracellular stores of serotonin and then inducing serotonin release. Pretreatment of mice with the serotonin inhibitor p-chlorophenylalanine (PCPA) abolished the fenfluramine inhibition of T-cell activation indicating that the fenfluramine inhibitory effect was mediated via endogenous spleen cell-derived serotonin. However, the PCPA treatment diminished T-cell activation. These results suggest that endogenous serotonin causes a biphasic dose-response effect on T-cell activity with serotonin being required for optimal T-cell function, low doses being immune stimulatory and higher doses being suppressive.

Protective Immunization Against the Intestinal Parasite Eimeria acervulina with Recombinant Coccidial Antigen

The gene encoding an immunodominant Eimeria acervulina merozoite surface antigen (EAMZ250) was expressed in bacteria as a fusion peptide with the galactose-binding protein (GBP) of Escherichia coli. Recombinant and control antigens were administered to 1-wk-old chickens by peroral inoculation with live nonpathogenic bacteria that were expressing GBP-EAMZ250 or GBP protein. The immunization elicited antigen-specific humoral and cellular immune responses as measured by ELISA and T-cell blastogenesis assay. In addition, chickens immunized with recombinant GBP-EAMZ250 exhibited significant protection against weight loss and intestinal lesions after E. acervulina challenge. Bacterial transformants were recoverable from the upper and middle intestine of inoculated chickens for various times after immunization. These data indicate that oral administration of live E. coli expressing a recombinant E. acervulina antigen is an effective means of inducing resistance to coccidiosis.

Immunosuppression in mice induced by cold water stress

A number of studies indicate that stress can result in suppression of the immune system in animals and man. Most of the studies have focused on alterations of lymphocyte function while only a few have investigated alterations of macrophage function or macrophage cytokine production. Macrophages play an essential role in homeostasis of the immune response. Indeed, the earliest events of the immune response occur in cells of the monocytic lineage, and their secretion of various cytokines may have both immunological and nonimmunological effects. The present studies were undertaken to determine whether alterations in macrophage physiology occur in mice subjected to a stress stimulus. Our studies in mice exposed to cold water stress for 4 days indicated reduced numbers of thymocytes and splenocytes, decreased T-cell blastogenesis, and reduced NK activity. Examination of elicited peritoneal macrophages from stressed mice revealed increased prostaglandin E 2 (PGE 2) secretion and decreased immune region associated antigen (Ia) expression in response to interferon-γ. Despite elevated PGE 2 levels, indomethacin was generally unable to restore depressed immune function. Of special interest was the finding that cell-associated and secreted interleukin 1 were significantly higher from unstimulated elicited macrophages from stressed mice. These results suggest that early in the response to stress, functions of a variety of cells within the immune system, especially macrophages, are altered and that dysregulated macrophage function may well contribute to the generalized suppression of the immune response in cold water stressed mice.