Lithium: a modulator of cyclic AMP-dependent events in lymphocytes?

Canine cyclic hematopoiesis is associated with abnormal purine and pyrimidine metabolism

Canine cyclic hematopoiesis is an autosomal recessive disease characterized by regular 11-13-d cycles of the neutrophil, reticulocyte, and platelet counts caused by a defect in regulation of marrow stem cell proliferation. Treatment with lithium abrogates cycling of the cell counts in these grey collie dogs. Aware of the defective lymphopoiesis associated with adenosine deaminase and purine nucleoside phosphorylase deficiencies, we hypothesized that abnormal purine or pyrimidine metabolism might be present in these dogs. Using high pressure liquid chromatography, we measured erythrocyte purine and pyrimidine nucleotide levels and plasma purine and pyrimidine nucleosides and bases in normal and grey collie dogs before and during lithium treatment. During neutropenic periods in the grey collies, erythrocyte ATP, GTP, and UTP levels were significantly elevated. Normal dogs made neutropenic with cyclophosphamide did not show such elevations. Lithium treatment normalized the levels of erythrocyte ATP, GTP, and UTP in the grey collies and eliminated the differences between normal and grey collie nucleotide levels. Plasma thymine levels were markedly increased during neutropenia in the grey collie but were not increased in cyclophosphamide-treated normal dogs. The finding of abnormal concentrations of purine and pyrimidine metabolites in these dogs suggest that a metabolic derangement in purine or pyrimidine metabolism may be the cause of the defective stem cell proliferation in this disease.

Enhancing effect of lithium and potassium ions on lectin-induced lymphocyte proliferation in aging and Down's syndrome subjects

The effect of different concentrations of LiCl or KCl (0.6-20 meq/liter) on PHA-stimulated lymphocytes from young, old, and Down's syndrome subjects was studied. LiCl showed a dramatic enhancing effect on [3H]thymidine incorporation induced by a suboptimal dose of PHA in old subjects and Down's syndrome patients. An increase of [3H]thymidine incorporation in human lymphocytes stimulated by a suboptimal dose of PHA was also observed with KCl. This effect was higher in old subjects than that observed in young and Down's subjects. LiCl and KCl can modulate and partially restore the derangement in early events of mitogen stimulation which seems to be present in lymphocytes from both old and Down's syndrome subjects.

[Humoral autoimmune phenomena during long-term lithium treatment with special reference to thyroid autoantibodies]

In a retrospective study, 58 outpatients under long-term therapy with lithium were examined with regard to humoral autoantibodies. Fifty-five schizophrenic outpatients under neuroleptic treatment served as controls. We examined antithyroidal antibodies (TAK, MAK), smooth muscle antibodies (SMA), antimitochondrial antibodies (AMA), and antinuclear antibodies (ANA). In the lithium group there was a significant higher prevalence of antithyroidal antibodies (33%) as compared to the control group (9%). Ten patients out of 19 patients with antithyroidal antibodies showed MAK as well as TAK; moreover we found a characteristic pattern: MAK greater than or equal to TAK. All lithium-treated patients were euthyroid. Five patients out of the group with antithyroidal antibodies had goiter, three showed temporarily elevated serum concentrations of basal thyroid-stimulating hormone (TSH). We did not find such elevated levels of TSH in the group of eight patients with goiter but without antithyroidal antibodies. There was neither a correlation between the examined parameters and the lithium serum concentration nor the additional psychotropic medication. Our results indicate a significant higher prevalence of antithyroidal antibodies under long-term therapy with lithium as compared to a psychiatric control group. We do not consider these autoimmune phenomena as relevant pathogenetic factors.

Carbamycholine modulation of E-rosette formation: identification of nicotinic acetylcholine receptors on a subpopulation of human T lymphocytes

We previously suggested that a population of T-suppressor cells carries acetylcholine receptors which may be involved in the regulation of the immune response. To identify cholinergic receptors on human T lymphocytes, we investigated the effects of carbachol, a cholinergic agonist, on E-rosette formation. Preincubation of normal human peripheral blood cells with carbachol resulted in a 30-40% reduction in numbers of E rosette-forming cells. Carbachol-induced inhibition of E-rosette formation was dose-dependent, temperature dependent, and reversible. The drug effects appeared to be mediated through a nicotinic acetylcholine receptor since d-tubocurarine (but not atropine) abrogated its activity. The expression of nicotinic receptors on a subset of human T cells may play an important role in the pathogenesis of certain diseases such as myasthenia gravis.

Lithium chloride induces partial responsiveness to LPS in nonresponder B cells

The lipopolysaccharide (LPS)-nonresponder mouse strains C3H/HeJ, C57BL/10ScCR and C57BL/10ScN do not respond to LPS acting as a polyclonal B-cell activator, a mitogen, or an adjuvant. The genetic basis for the defective LPS response has been extensive studied in C3H/HeJ and C57BL/10ScCR mice, in which it was demonstrated that a single gene locus on chromosome 4 was responsible for LPS unresponsiveness. Lithium chloride, a potent inhibitor of adenylate cyclase, not only improved lymphocyte activity in a patient with adenosine deaminase deficiency but also enhanced the phytohaemagglutinin (PHA)-induced responses of normal human lymphocytes. Therefore, we investigated whether LiCl could restore LPS responsiveness in spleen cells of C3H/HeJ mice. We show here that LPS, in the presence of LiCl, induced polyclonal IgM and IgG antibody formation and DNA synthesis in C3H/HeJ mouse spleen cells in vitro. Moreover, LiCl (10 mM), which by itself is non-mitogenic, increased RNA synthesis in spleen cells from both LPS-nonresponder and high responders strains; in contrast, LPS failed to increase RNA synthesis in cells from such LPS-nonresponder strains as C3H/HeJ and B10ScCr mice.

Membrane biophysical studies of lymphocytes and erythrocytes in manic-depressive illness

Recent research suggests that manic-depressive illness is associated with a membrane abnormality which is detectable in peripheral tissues. Using fluorescence spectroscopy, the cellular membrane dynamics of intact erythrocytes and lymphocytes from manic-depressive patients and controls were studied in a double blind fashion. A cross-sectional analysis of membrane dynamics was obtained by using fluorescent probes with known affinity for specific regions of erythrocyte membranes. This preliminary study demonstrates alterations in the hydrocarbon region of erythrocyte membranes and the cell surface of lymphocytes in patients with manic-depressive illness. These abnormalities appear to be independent of clinical symptomatology and medication. The membrane abnormality demonstrated by fluorescence spectroscopy may provide clues to the molecular pathophysiology in manic-depressive illness, as well as a method of diagnosis in presymptomatic patients.

Lithium enhances growth of human leukaemia cells in vitro

Lithium is known to cause leucocytosis in normal humans, and lithium salts have been used therapeutically in attenuating leucopenia in patients undergoing chemotherapy. Recent reports also described leukaemia development during lithium treatment. We have investigated the effect of lithium chloride on the proliferation of human myeloid, erythroblastic, and T- and B-lymphoblast leukaemia cells in vitro. Colony formation by cells of the myeloid leukaemia lines HL-60 and KG-1 was enhanced by lithium chloride, and maximal stimulation was seen at 5 X 10(-4) M. Lithium also increased the proliferation of KG-1a cells, a subline of KG-1 cells that does not respond to colony-stimulating factor, indicating a direct growth-promoting effect on myeloid leukaemia cells. Lithium was found to enhance colony formation by the T-lymphoblast cell line MOLT 4 and the B-lymphoblast line IM-9 at concentrations between 10(-6) and 10(-3) M. The addition of lithium chloride to murine Friend or human K-562 erythroleukaemia cells also caused an augmentation in colony formation. These observations may have relevance to the therapeutic use of lithium in patients with haematological malignancies.

Partial restoration of local GVH reaction in cancer patients by depletion of theophylline-sensitive suppressor T-cells

Theophylline-resistant T-cell subpopulations were assessed in terms of numbers and function among patients with disseminated cancer, and compared to normal controls. Within the total E-rosetting T-cells (65 +/- 6.5% for normal donors versus 34 +/- 1.0% for cancer patients; P less than 0.001) the proportion of theophylline-resistant Te cells was 56 +/- 1.5% and 26.6 +/- 1.1%, respectively (P less than 0.001). This significant difference in distribution between theophylline-resistant (effector) and theophylline-sensitive (suppressor) cells in favor of the latter was also reflected by the poor performance of unseparated T-cells in the local GVH reaction. Thus, the mean GVH reaction among normal donors was 159 +/- 30 mm3 versus 44 +/- 28 mm3 among cancer patients (P less than 0.001). Removal of the theophylline-sensitive suppressor T-cells resulted in significant augmentation of the local GVH reaction among normal donors and in significant, although partial, immune restoration of the local GVH reaction in some patients but not in others. The mean local GVH reaction after removal of theophylline-sensitive suppressor T-cells was 196 +/- 89 mm3 among normal donors and 68 +/- 46 mm3 among cancer patients (P less than 0.05). This immune restoration following depletion of suppressor T-cells was only partial among cancer patients because of an apparent intrinsic defect in the capacity of their effector T-cells to exert vigorous local GVH reaction. In one small group of four patients, this intrinsic defect was so profound that even after removal of the theophylline-sensitive suppressor cells, the restoration of the local GVH reaction was negligible (12 +/- 10.8 mm3 versus 24 +/- 9.8 mm3; P greater than 0.1). The quantitative and qualitative changes in effector and suppressor T-cell distribution during the development of the malignant process and the possible interaction between them are discussed.

Human leukocyte interferon-mediated granulopoietic differentiation arrest and its abrogation by lithium carbonate

Interferon has been shown to inhibit erythropoietic and granulopoietic differentiation. Since lithium carbonate (Li) elevates granulocyte levels in a variety of neutropenic disorders, we investigated the effect of Li on human leukocyte interferon (HLIF)-mediated inhibition of granulopoietic differentiation. Using an agar culture technique for cloning granulocyte-macrophage progenitor cells (GM-CFC), we demonstrated that Li blocks HLIF-induced granulopoietic differentiation arrest in a dose-dependent manner. Results of removal of T lymphocytes from marrow cells suggest that this Li effect is not mediated through marrow T lymphocytes.

Lithium modulates mitogen induced natural killer activity and interferon production

Incubation of human peripheral blood mononuclear cells with lithium ions in combination with either phytohemagglutinin or concanavalin A resulted in increased natural killer cell activity. Maximum augmentation was observed following three days of culturing peripheral blood mononuclear cells with mitogens and lithium and was accompanied by increased interferon production. Lithium did not enhance the natural killer cell activity of peripheral blood mononuclear cells cultured with Poly I:C.

Cyclic neutropenia and T lymphocyte suppression of granulopoiesis: abrogation of the neutropenic cycles by lithium carbonate

To investigate the mechanisms of cyclic neutropenia, we studied the capacity of a patient's T lymphocytes (TLp) to interact with monocyte-macrophages from her normal HLA-identical sibling (MOb) in the elaboration of colony-stimulating activity (CSA). TLp obtained at the time of decreasing neutrophil counts, increased CSA elaboration (p less than 0.056) when incubated at a 1:1 ratio with MOb. Increasing the TLp to MOb ratios to 3:1 or 5:1 progressively decreased CSA. Also, lithium carbonate, which ordinarily prevents concanavalin A activation of suppressor TL, failed to do so, suggesting that preactivated suppressor TL were present in the patient while neutrophil levels were falling. In similar experiments performed while neutrophil levels were rising these activated suppressor TL were absent. These data suggest that some patients with cyclic neutropenia may have a cyclic increase in suppressor TL activity. As predicted by our in vitro experiments, lithium carbonate administration did not abrogate the first neutropenic cycle, but it did mitigate subsequent cycles.

The mechanism of lithium carbonate-induced augmentation of colony-stimulating activity elaboration in man

Lithium carbonate (Li) has been reported to elevate granulocyte counts in patients with certain neutropenic disorders and to improve chemotherapy-induced granulocytopenia. To investigate the mechanisms involved in the increase in myelopoiesis, the effect of Li on monocytemacrophage (M phi)- and T-lymphocyte (TL)-derived colony-stimulating activity (CSA) were studied in vitro. Li induced a dose-related increase in both M phi- and TL-derived CSA over that in non-Li-stimulated cell populations. However, the increase was significant (p less than 0.007) only at a higher concentration of Li (2 mEq/l). The results of co-incubating TL with M phi with or without Li indicated that Li significantly enhanced synergistic CSA production by the two cell populations (p less than 0.02). We further demonstrated the presence of a larger proportion of M phi with TL rosettes in the presence of Li (62%) than in its absence (21%). Further experiments with concanavalin A (Con-A)-inducible suppressor TL suggested that Li effectively blocks the suppressor TL-mediated suppression of CSA. These data suggest that Li enhances M phi and TL interaction which results in an augmented CSA elaboration. Further, Li would be more effective in those neutropenic disorders associated with enhanced suppressor TL activity. For an optimal effect, however, Li would require appropriately functioning M phi and non-suppressor subsets of TL and an intact stem cell pool.

Abnormal suppressor cell function in atopic dermatitis

A status of suppressor cells in patients with atopic dermatitis was studied. As a group, they showed absent concanavalin A-inducible suppressor cell function as measured by proliferative responses to pokeweed mitogen and decreased function as measured by responses to phytohemagglutinin or concanavalin A. Similarly, preincubation in medium enhanced proliferative responses in normal donors but not in atopic dermatitis patients, suggesting an absence of a short-lived suppressor cell population in the latter group. Suppressor cell function correlated negatively with log10 of serum IgE concentrations. Theophylline-sensitive suppressor cell numbers were significantly decreased in atopic dermatitis patients (p less than 0.01). In vitro preincubation of normal lymphocytes with aminophylline or isoproterenol (10 microgram/ml) enhanced subsequent proliferative responses to pokeweed mitogen. In contrast, actual depression was seen with cells from atopic dermatitis patients, suggesting abnormal immunomodulatory effects of these drugs in the disease.

Dysfunctions of pokeweed mitogen-stimulated T and B lymphocyte responses induced by gammaglobulin therapy

Lymphocytes obtained from nonimmuno deficient children treated with commercially available preparations of gammaglobulin failed to proliferate and to mature into plasma cells in vitro after stimulation with pokeweed mitogen. The influence of the treatment on lymphocyte functions varied according to the cell population considered. A T helper cell activity was detected in these patients but only in the cell subset bearing receptors for IgG after irradiation. T lymphocytes exerted a suppressive effect that disappeared after irradiation or incubation at 37 degrees C. The suppressive cells were found among E rosette-forming cells depleted of leukocytes bearing receptors for IgG. Their suppressive effect was expressed only in the presence of normal radioresistant T lymphocytes that did not bear Fc receptors for IgG. Similar dysfunctions could be induced in vitro by incubation of normal T and B lymphocytes with gammaglobulin preparations. Because F(ab)'2 fragments or deaggregated preparations of gammaglobulin failed to activate T suppressor lymphocytes, this activation was likely triggered by attachment of Fc portion of denatured IgG to the corresponding membrane receptor. This activation step was prostaglandin E(2)-dependent, suggesting that activated monocytes were involved in the activation process. B lymphocyte responses appeared directly inhibited by attachment of denatured gammaglobulin on membrane Fc receptor. Our observations suggest that immunological effects of gammaglobulin therapy are not limited to antibody transfer, since it also induces subtle modifications of in vitro pokeweed mitogen-stimulated T and B cell responses. These modifications must be considered in interpreting results obtained in immunodeficient patients investigated under gamma-globulin therapy.

Adjuvant effects of lithium chloride on human mononuclear cells in suppressor-enriched and suppressor-depleted systems

Lithium enhances several in vitro indices of immune function, including thymidine uptake by mitogen-stimulated human mononuclear cells. To further characterize the mechanism of action of lithium and to determine whether it acts by abrogating suppressor cell activity or by enhancing helper cell function, we have compared the effects of lithium on the mitogenic response of normal, suppressor-depleted and suppressor-enriched mononuclear cell preparations. In normal cultures, lithium enhanced thymidine uptake in response to concanavalin A (Con A) and phytohemagglutinin (PHA). In the suppressor-depleted cultures, thymidine uptake after Con A stimulation was significantly higher than in normal cultures, and was further enhanced by lithium. In the suppressor-enriched system, response to PHA was significantly lower than in normal cultures, and addition of lithium reversed the observed suppression. These results indicate that lithium may be enhancing thymidine uptake in response to mitogen at least in part by abrogating suppressor cell activity. The observed increase in thymidine incorporation in the suppressor-depleted cultures suggests that lithium may also have a direct stimulatory effect on helper cell activity.

Subsensitivity of human beta-adrenergic adenylate cyclase after salbutamol treatment of depression

Although numerous studies have suggested that depression may be associated with a reduction in synaptic noradrenaline in the brain, direct beta-adrenergic receptor agonist have only recently been tested in the treatement of depression. Moreover, newer theories of antidepressant action suggest that a reduction in beta-adrenergic receptor sensitivity is a better correlate of antidepressant treatment than noradrenaline turnover changes. Eleven depressed patients were treated with salbutamol, a beta-2-adrenergic agonist, and beta-2-adrenergic receptor sensitivity was evaluated before, during, and after treatment. beta-Adrenergic receptor sensitivity was evaluated by measuring the plasma cyclic AMP increase after an IV dose of salbutamol. The beta-adrenergic agonist exhibited antidepressant efficacy and induced subsensitivity of the beta-adrenergic adenylate cyclase with a time course paralleling the antidepressant effects. The results support the concept that receptor sensitivity changes occur during antidepressant therapy.

Induction of growth in kidney epithelial cells in culture by Na+

The role of Na+ in the regulation of cell growth was examined in quiescent, high-density cultures of kidney epithelial cells of the BSC-1 line. The addition of NaCl to the medium increased the number of cells initiating DNA synthesis in a concentration-dependent manner after serum stimulation. In the presence of added NaCl, cells in confluent cultures grew to high density at an increased rate, whereas growth in sparse cultures was retarded. These results suggest that, in the presence of serum, Na+ can act as a mediator of the events that initiate cell proliferation.

Cellular mechanisms of restricted immunoglobulin formation in the human neonate

The functional capacity of human neonatal B lymphocytes has been investigated by in vitro methods using T lymphocyte-dependent (pokeweek mitogen, PWM) and -independent (Epstein-Barr virus, EBV) polyclonal B cell activators. B cell activation of single cells was detected by class-specific immunoglobulin (Ig) secretion using a reversed hemolytic plaque assay. It was found that neonatal B cells were triggered to secretion of IgM by EBV, with a magnitude comparable to adult levels, but that, in contrast to B cells from adults, they did not secret IgG. Cord lymphocytes did not secret Ig although they displayed a sizable DNA synthetic response to PWM. Using cell separation and culture experiments, it was shown that (allogeneic) adult T lymphocytes could restore cord B cell responsiveness to PWM and that cord T lymphocytes could not cooperate with adult B cells. In addition to this immaturity of cord T helper function for antibody synthesis, we found cells in the cord T cell-enriched fraction which inhibited the polyclonal response of adult lymphocytes to both PWM and EBV. These lymphocytes suppressed adult B lymphocytes directly but appeared ineffective against neonatal B lymphocytes themselves. The nature of these suppressing cells and their possible role in the fetal/maternal relationship are a matter of speculation.

Studies of T- and B-cell interactions in adult patients with combined immunodeficiency

Cellular interactions involved in the pathogenesis of hypogammaglobulinemia were studied in six patients with common variable immunodeficiency. Amounts of immunoglobulin (Ig)G and IgM in the supernate of pokeweed mitogen-stimulated cocultures of normal and immunodeficient mononuclear cells were measured by radioimmunoassays. Mononuclear cells from three of six patients inhibited Ig production of normal B cells (P < 0.005). When purified patient and normal T cells were added to B cells in various autologous or allogeneic combinations, it was observed that immunodeficient T cells (AT) from four patients suppressed normal IgM synthesis. Allogeneic normal T cells did not provide help for B cells from these same immunodeficient patients. In two patients, autologous T cells were able to help autologous B-cell IgM synthesis in vitro. In five patients, AT cells inhibited normal B-cell IgG synthesis. Removal of T cells bearing Ia determinants or T cells with Fc-IgG receptors did not diminish the suppressive effect of AT cells on normal B-cell Ig synthesis. Addition of indomethacin, a prostaglandin synthetase inhibitor, did not abrogate the suppressive effect of immunodeficient mononuclear cells. Addition of hydrocortisone succinate (10 muM) did reverse the suppressive effect of AT cells on IgM production in one patient; however, no in vitro reversal of suppressor cell effect was recorded in five. Suppression by immune-deficient T cells was eliminated by 2,000 rad of x-ray irradiation in three patients. After x-ray irradiation immunedeficient T cells could function as helpers of normal B cells.

Characterization of lithium effects on two aspects of T-cell function

Cell surface receptors receive, transduce and relay a variety of environmental signals. These phenomena, which have been extensively characterized in non-lymphoid cells, also appear to play a crucial role in dictating the degree of lymphocyte responsiveness. The nature of these regulatory events is only beginning to be unraveled but the adenylate cyclase-cyclic AMP axis appears to be one of the important controlling systems. Lithium appears to be as important a modulator of lymphocyte responsiveness as previously shown for a variety of other cells and the mechanism of action, in general, is consistent with its role as a putative blocker of adenylate cyclase activation. Indeed, lithium may exert its role as a regulator of lymphocyte responsiveness by acting on specific lymphocyte subpopulations. Direct proof for this is still wanting and consideration of its capacity for action as an imperfect substitute for normal extra- or intracellular cations or on the physiochemical state of the plasma membrane is necessary. Nevertheless, these studies indicate the validity of using lithium for assessing the role of the lymphocyte adenylate cyclase-cyclic AMP system in the generation and expression of regulatory signals leading to modulation of the immune system.

Lithium as an immunologic adjuvant

Lithium, an adenylate cyclase inhibitor, stimulates a variety of in vitro indices of immune function, including proliferation of lymphocytes in response to mitogens, rosette formation by T-cells and phagocytosis by macrophages. Lithium enhances these immunologic responses at concentrations comparable to those achieved in patients receiving lithium for treatment of manic-depressive disorders. Lithium may prove to have important therapeutic applications as an immune adjuvant, particularly in immune deficiency states associated with excessive C-AMP production.