Thymosin alpha 1 modulates the expression of high affinity interleukin-2 receptors on normal human lymphocytes

Thymosin alpha 1 effects, in vitro, on lymphokine-activated killer cells from patients with primary immunodeficiencies: preliminary results

In patients with primary immunodeficiencies the role of natural killer (NK)- and lymphokine (IL-2)-activated killer (LAK)-cells is not yet satisfactorily established. Using a clonogenic assay with K562 leukemia target cells, we studied their NK- and LAK-cell activity in vitro. Moreover, the effect of thymosin alpha 1 (T alpha 1) on LAK-cell activity was studied in 11 patients with different immunodeficiencies. The results were compared with data of healthy controls (n = 11) and cord blood samples (n = 6). Common variable immunodeficiency patients demonstrated a mean LAK-cell activity of about 65% of normal controls and cord blood samples. The moderately reduced LAK-cell activity was not affected by T alpha 1. In the immunodeficient other patients, low levels of LAK-cell activity with a mean value of 10% of normal controls were seen. The mean LAK-cell activity could be improved by T alpha 1: three patients showed an improvement of their LAK-cell activity up to 25-30% after T alpha 1 administration in vitro, but in one case T alpha 1 was without any effect. Analysis of the expression of the surface markers CD8, CD16, CD57 and CD8/CD57 revealed that only CD16 positive lymphocytes were significantly less in immunodeficient patients. We found a linear correlation between LAK-cell activity and CD8/CD57 double positive lymphocytes in all patients. Our results demonstrate that suppressed LAK-cell activity from immunodeficient patients can be individually improved by T alpha 1. Further in vivo studies should evaluate thymic peptide immunotherapy for individual immunodeficient patients.

Effect of triiodothyronine and in vitro growth hormone on avian interleukin-2

One-day-old chickens were treated with varying levels of triiodothyronine (T3) added to the diet. At 28 days of age, the IL-2-like activity in the splenocyte culture supernatants were assessed. The lowest dose of T3 (0.1 ppm) enhanced IL-2-like activity while the highest dose (1.0 ppm) was significantly suppressive. The intermediate dose elicited varying effects. Recombinant chicken growth hormone (rcGH) was added to some cultures 24 h prior to IL-2 assay. In vitro rcGH significantly depressed the IL-2-like activity of splenocytes from animals given the low T3 diet. The addition of varying concentrations of T3 in vitro to splenocytes from non-T3-supplemented chickens had no effect on the IL-2-like activity. These results indicate that in vivo supplementation of low dietary T3 but not in vitro T3 is effective in enhancing avian IL-2-like activity. The addition of rcGH in vitro can modify this response.

Anti-tumor effect of combined treatment with thymosin alpha 1 and interleukin-2 after 5-fluorouracil in liver metastases from colorectal cancer in rats

We studied the effect of combined chemo-immunotherapy, 5-FU followed by thymosin alpha 1 (T alpha 1) and interleukin-2 (IL-2) at low doses, on liver metastases from colorectal cancer, induced by splenic injection of DHD/K12 cells (1,2-dimethylhydrazine-induced colon adenocarcinoma) in syngeneic BDIX rats. The presence of liver metastases was checked by laparotomy 14 days after tumor-cell injection. Evaluable rats were assigned randomly to 5 experimental groups designated as control, 5-FU, IL-2, 5-FU/IL-2 and 5-FU/T alpha 1/IL-2. 5-FU was administered i.v. as a continuous infusion for 7 days by an osmotic device implanted surgically. T alpha 1 and IL-2 were administered for 4 days and repeated after 11 days. Combined chemo-immunotherapy was shown both to significantly reduce the growth of liver metastases and to prevent extra-hepatic spread. 5-FU/T alpha 1/IL-2 also improved survival rate. Combined immunotherapy after 5-FU restored NK activity of the peripheral-blood-mononuclear-cell (PBMC) in tumor and/or 5-FU immunodepressed rats and enhanced PBMC cytotoxic activity against the DHD/K12 autologous cell line. This model was devised to mimic the clinical situation of unresectable liver metastases.

THF gamma 2 stimulates cytokine release by peripheral blood mononuclear cells of patients with chronic hepatitis B virus infection

A recent study indicated that thymic hormones have antiviral effects in human hepatitis B virus infection and woodchuck hepatitis virus infection. These hormones are known to exert immunomodulatory effects on lymphocyte maturation and function; because these are abnormal in patients with chronic hepatitis B virus infection, we have examined the effects of a thymic hormone (THF gamma 2) on peripheral blood mononuclear cells from patients with chronic hepatitis B virus infection. THF gamma 2 (50 or 150 ng/ml) alone was without effect; in the presence of low doses of the mitogen phytohaemagglutinin, it had a broad effect in patients and controls. The effect on interleukin-2 production was greater in patients than controls with a significant increase in production at 150 ng/ml for patients alone (p = 0.037). Tumour necrosis factor alpha production was enhanced in all patients and controls, with a greater effect seen at 150 ng/ml THF gamma 2 than 50 ng/ml. There was no effect on interferon gamma production or on the expression of membrane markers of T-cell activation. THF gamma 2 has substantial immunomodulatory activity in chronic hepatitis B virus carriers and in vivo assessment of THF gamma 2 in chronic hepatitis B virus is indicated.

Thymosin alpha-1 as adjunct for conventional therapy of malignant tumors: a review

T alpha 1, a 28-amino-acid peptide, is derived from PT alpha, which is an intracellular, nonsecretory protein of unknown function. Both T alpha 1 and PT alpha are found in the blood of normal individuals. Subcutaneous and intramuscular injections of T alpha 1 in doses up to 9.6 mg/m2 are tolerated without side effects, and 0.9 mg/m2 injections raise the serum level approximately 30-fold after 1 hr of administration, which slowly returns to baseline within 24 hr. In vitro, and perhaps in vivo, T alpha 1 restores normal T-cell function. It increases IL-2 production and IL-2 receptors in normal mitogen-stimulated T cells and stimulates IL-3 production in immunocompromised mice. The dose-response relationship for these effects is not linear and may be bimodal. T alpha 1 binds to VIP receptors and inhibits in vitro and xenograft growth of non-SCLC cell lines. In patients with nonbulky carcinomas who have received standard therapy, T alpha 1 is possibly effective in prolonging the time to relapse and in improving survival. At present there is a great need to clearly define the clinical role of T alpha 1 in cancer patients. A major problem encountered in studies with T alpha 1 will, however, be the present lack of knowledge with regard to its mechanism in effecting tumor growth. It is not at all clear whether its immunomodulatory functions, its interaction with VIP receptors, or none of these mechanisms are related to its antineoplastic activities. In addition, the apparent nonlinear dose-response relationship will make it difficult to choose a reasonable dosing schedule for clinical trials. This is particularly apparent in light of the experimental animal data summarized above where a tumor response was seen at doses of 4 micrograms/kg and 400 micrograms/kg but not at 0.4 microgram/kg and 40 micrograms/kg. This dose range could conceivably be given to humans since 9.6 mg/m2, the maximum dose given to humans without major side effects to date, is roughly equivalent to 250 micrograms/kg. At this time a reasonable clinical approach would be a well-designed risk factor stratified phase III clinical trial using 0.9 mg/m2 T alpha 1 subcutaneously twice a week compared to a control group to substantiate the data reported by Schulof et al. Before such data are available, T alpha 1 should not be used in clinical oncology.

Expression of alpha-thymosins in human tissues in normal and abnormal growth

Radioimmunoassays specific for the N and C termini of human prothymosin alpha and the N terminus of human parathymosin alpha were employed for the measurement of the levels of alpha-thymosins in human thymus, spleen, and liver during normal growth and intestine and breast in malignant growth. A differential expression of the two alpha-thymosins was observed in thymus (prothymosin alpha-rich) and liver (parathymosin alpha-rich). A decline in the levels of both alpha-thymosins was found with age, with prothymosin alpha in thymus showing the sharpest change (15- to 30-fold). The levels of both alpha-thymosins were higher in malignant tissues as compared with healthy ones. In breast cancer, in particular, the mean increase for prothymosin alpha and parathymosin alpha was 17.9- and 11.5-fold, respectively. The major crossreactive material was characterized in all cases as intact prothymosin alpha and parathymosin alpha. These results suggest an in vivo relationship of the expression of alpha-thymosins with the human tissue cell proliferation activity.

Thymosin stimulates interleukin-6 production from rat spleen cells in vitro

Thymosin fraction 5 (TF5) is a partially purified preparation of bovine thymus that affects the differentiation and function of T-cells in vitro. Interleukin-6 (IL-6) is a pleiotropic cytokine that induces terminal maturation of B-cells and T-cell activation and differentiation. Although TF5 had previously been shown to stimulate the production of a number of lymphokines, its effects on IL-6 were not known. In this study we determined the effect of TF5 on IL-6 production from rat spleen cells in vitro. TF5 (100 micrograms/ml) stimulated IL-6 production from splenocytes (0.75-3.0 x 10(5) cells/well) in the presence of 0.008-0.2 micrograms/well of the T-cell mitogen concanavalin-A (con-A) by 10-20 fold during a 72 h incubation period. Dose-response studies demonstrated that 10 micrograms/ml of TF5 was the lowest concentration capable of enhancing IL-6 production. The ability of TF5 to stimulate IL-6 production in the presence of con-A could be demonstrated within 24 h of incubation; longer incubation periods (48-72 h) correlated with further enhancements of IL-6 production. Partial purification of the IL-6-inducing activity from TF5 resulted in three subfractions possessing activity in the presence of con-A (MB2, MB3, MB7) and one in the absence of con-A (MB2). The previously characterized thymosin peptides T alpha 1 and T beta 4 had no effect on IL-6 production in the absence or presence of mitogen. This study reports a new biological activity for TF5 and suggests that a novel constituent of TF5 may enhance the production of IL-6 from spleen cells.

Thyroid function and thyroid autoimmunity independently modulate serum concentration of soluble interleukin 2 (IL-2) receptor (sIL-2R) in thyroid diseases

OBJECTIVE

The serum concentration of soluble interleukin-2 receptor (sIL-2R) is a marker of T-lymphocyte activation. Increased circulating sIL-2R has been reported in untreated Graves' disease. This finding has been interpreted as the consequence of the autoimmune activation, but recent data suggest that sIL-2R is directly correlated to thyroid state. The aim of this study was to elucidate the respective roles of autoimmunity and thyroid function in modulating serum sIL-2R.

DESIGN AND PATIENTS

sIL-2R was evaluated in 20 normal euthyroid subjects and in a large series of patients with autoimmune and non-autoimmune thyroid disorders in different functional state.

MEASUREMENTS

sIL-2R was assayed by a solid-phase monoclonal antibody assisted ELISA method.

RESULTS

Serum sIL-2R in normals was 461 +/- 186 U/ml (mean +/- SD). Increased sIL-2R was found in 61 hyperthyroid patients with Graves' disease (1610 +/- 962 U/ml, P < 0.0001) and in 23 with toxic adenoma (1121 +/- 598 U/ml, P < 0.0001). Restoration of euthyroidism lowered to normal sIL-2R in both groups. Serum sIL-2R was higher in euthyroid Graves' disease patients with active than in those with non-active ophthalmopathy. Decreased serum sIL-2R (228 +/- 93 U/ml, P < 0.0001) was found in 30 patients hypothyroid after total thyroidectomy. Highly variable circulating sIL-2R (range 100-1456 U/ml, mean +/- SD: 379 +/- 301 U/ml) was found in 49 patients with hypothyroid Hashimoto's thyroiditis (P = NS vs normals; P < 0.02 vs post-thyroidectomy hypothyroid patients). Treatment with L-thyroxine increased sIL-2R in all thyroidectomized and in the majority of Hashimoto's thyroiditis patients. In individual Hashimoto's thyroiditis patients (mostly with increased serum sIL-2R), L-thyroxine caused a decrease of circulating sIL-2R, sIL-2R was normal in 29 patients with euthyroid Hashimoto's thyroiditis. Both in Graves' disease and in Hashimoto's thyroiditis, no correlation was found between sIL-2R and anti-thyroglobulin, anti-thyroid peroxidase and anti-thyrotrophin-receptor autoantibodies. Highly significant positive correlation between serum thyroid hormones and sIL-2R was found in all study groups.

CONCLUSIONS

In thyroid disorders thyroid hormones are the main regulator of serum sIL-2R concentration. The contribution of autoimmune activation may be detected only in some patients with autoimmune hypothyroidism, while in Graves' disease the role of the immune system is masked by the hyperthyroid state.

Mixed interleukins and thymosin fraction V synergistically induce T lymphocyte development in hydrocortisone-treated aged mice

Analysis of the role of interleukins in T cell ontogeny in vitro indicates that the regulation of T cell development involves interleukins (ILs) as well as thymic hormones (THs). In order to assess their respective roles in T lymphocyte development in vivo, chemically thymectomized mice were treated with ILs and THs. After 2 days of hydrocortisone treatment, aged mice showed acute thymic involution (weight was less than 30% of control) and reduced spleen size (less than 80% of control) with progressive recovery to 8 days. After 2 days of hydrocortisone treatment, adult mice were injected for 5 days with mixed buffy coat interleukins (BC-IL; 50 units IL2 equivalence), purified IL2 (50 units), rIL1 beta (4 ng), and thymosin fraction V (TF5; 100 micrograms). The animals were sacrificed and spleens and thymuses were analyzed for weight, cellularity, T cell number, subsets, and function as determined by proliferative responses to concanavalin A and ILs. BC-IL treatment increased the recovery of spleen and thymus weights and cellularity with corresponding augmentation of number and function of T lymphocytes; neither IL1 or IL2 or their combination had this effect. TF5 had no effect alone but strongly potentiated the effect of BC-IL on T lymphocyte function. These data indicate that BC-IL in combination with thymic peptides potently promotes T lymphocyte development. The combination may be therapeutically relevant for immunorestoration.

Interleukin 1 regulates secretion of zinc-thymulin by human thymic epithelial cells and its action on T-lymphocyte proliferation and nuclear protein kinase C

Thymic epithelial cells (TEC) are known to secrete thymic hormones that influence maturation of T lymphocytes. One of these peptides, thymulin, requires zinc in an equimolar ratio for biological activity. A previous study [Cousins, R. J. & Leinart, A. S. (1988) FASEB J. 2, 2884-2890] showed that interleukin 1 (IL-1) in vivo stimulates zinc uptake by the thymus. Both the alpha and beta forms of IL-1, which stimulate proliferation of human TEC, also stimulate their uptake of zinc in vitro, and this latter stimulation is both dependent and independent of proliferation. Zinc induces zinc accumulation without proliferation. Two other stimulants of proliferation, bovine pituitary extract and epidermal growth factor, stimulate zinc uptake by TEC, but only in a manner dependent on proliferation. Utilizing in situ hybridization, we show that the IL-1 alpha and beta forms and zinc induce metallothionein mRNA expression TEC. Metallothionein is thought to be involved in the transfer of zinc to thymulin. IL-1 was shown to stimulate the secretion of thymulin as measured both by its ability to stimulate induction of IL-2 receptor-positive lymphocytes from human peripheral blood lymphocytes and by the azathioprine-sensitive rosette assay. In addition, the zinc-thymulin complex in the presence, but not absence, of IL-1 stimulates nuclear protein kinase C in isolated lymphocyte nuclei. IL-1 apparently regulates the synthesis or secretion and delivery of zinc-thymulin complex to the T-lymphocyte system.

Combination therapy with thymosin alpha 1 potentiates the anti-tumor activity of interleukin-2 with cyclophosphamide in the treatment of the Lewis lung carcinoma in mice

In this study we have investigated the effects of thymosin alpha 1 (T alpha 1) and interleukin-2 (IL-2), singly or in combination with cyclophosphamide (CY), on tumor growth, survival and cytotoxicity in C57Bl/6NCrlBR mice with Lewis lung carcinoma (3LL). Combined administration of T alpha 1 plus IL-2, after CY treatment, was much more effective than use of each biological response modifier (BRM) alone, and induced complete tumor regression in all of the mice studied. Combination immunotherapy alone without CY only slightly reduced the rate of tumor growth, and these results are in accordance with previous studied which showed that the 3LL carcinoma is resistant to cytokines. Combined chemo-immunotherapy also increased the cytotoxicity of spleen cells and markedly enhanced long-term survival in all treated animals. Depletion of immune cells, using either total-body sub-lethal irradiation (400 rads) or antibodies directed against T-cell (anti-CD4 and CD8) or NK-cell (anti-asialo GM1) populations, abolished the positive response to combination therapy. Histological analysis of the tumors obtained from mice treated with combination chemo-immunotherapy revealed a high number of infiltrating lymphoid cells surrounding a well-circumscribed area of necrosis consisting solely of dead cells. Our studies show that T alpha 1 potentiates IL-2-induced cytotoxic activities in vitro as well in vivo, and that these compounds have a powerful anti-tumor action when associated with chemotherapy.

Circulating soluble interleukin 2 receptor concentration is increased in both immunogenic and nonimmunogenic hyperthyroidism

High serum concentration of soluble interleukin-2 receptor (sIL-2R) is considered a reliable marker of T lymphocyte activation. It has been recently reported that sIL-2R levels are increased in untreated Graves' disease. This finding has been interpreted as the consequence of an active autoimmune state, but the relevance of the thyroid function per se was not investigated. In the present study we assayed sIL-2R by ELISA in 20 normal subjects and in a series of patients with immunogenic (Graves' disease, GD) or nonimmunogenic (toxic adenoma, TA) hyperthyroidism. Significant increased concentrations of sIL-2R were found in 46 patients with untreated hyperthyroid GD (mean +/- SD: 1,683 +/- 1016 U/ml, vs 461 +/- 186 U/ml in normal controls, p less than 0.0001) and in 21 with untreated TA (1,111 +/- 617 U/ml, p less than 0.0001 vs normals). Restoration of the euthyroid state by antithyroid drugs or 131I administration was associated with a normalization of sIL-2R (516 +/- 174 U/ml in 38 patients with GD and 365 +/- 90 U/ml in 12 with TA; p = NS vs normals and p less than 0.001 vs the untreated state for both groups). A highly significant positive correlation between serum sIL-2R and free triiodothyronine (FT3) (r = 0.724, p less than 0.0001) or free thyroxine (FT4) (r = 0.698, p less than 0.0001) concentrations was found in combined sera obtained from all untreated and treated patients, irrespectively of the autoimmune or nonautoimmune nature of the underlying hyperthyroid disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Suppression by Trypanosoma brucei rhodesiense of the capacities of human T lymphocytes to express interleukin-2 receptors and proliferate after mitogenic stimulation

We studied the suppressive effects induced in phytohemagglutinin (PHA)-stimulated human peripheral blood mononuclear cells (PBMC) by purified blood forms of Trypanosoma brucei rhodesiense. The parasite was found to markedly impair lymphocyte proliferation (measured in terms of [3H]thymidine incorporation). The extent of this effect increased with parasite concentration and was not due to mitogen absorption, depletion of medium nutrients, or PBMC killing by the parasite. Significant reductions in interleukin-2 receptor (IL-2R) expression, determined by flow cytometric analysis, were also observed in PHA-stimulated PBMC cultured in the presence of T. b. rhodesiense as evidenced by marked decreases in the surface density of the receptor. Concomitant decreases in the percentage of IL-2R+ cells were recorded in approximately half of the experiments. A discrete, dimly stained subpopulation of IL-2R+ cells were consistently demonstrable whether or not a reduction in the percentage of IL-2R+ cells occurred. Living, but not glutaraldehyde-fixed, parasites suppressed IL-2R expression. In kinetic studies, a low but reproducible level of suppression of IL-2R was demonstrable as early as 6 h after PHA stimulation; the extent of this effect became considerably more pronounced as additional culture time elapsed. Levels of IL-2 biological activity in cocultures of T. b. rhodesiense with PHA-stimulated PBMC were comparable with or higher than those present in control cultures lacking the parasite. Therefore, insufficient levels of this cytokine would be an unlikely explanation for the noted suppression of IL-2R expression and lymphoproliferation. These effects of T. b. rhodesiense could represent an important component of the mechanism by which immunosuppression develops in African sleeping sickness.

Thymosin alpha 1 potentiates interleukin 2-induced cytotoxic activity in mice

We have investigated the effects of interleukin 2 (IL-2) on cytotoxic activity of spleen lymphocytes, from normal and cyclophosphamide (200 mg/kg) or B-16 melanoma suppressed mice, after in vitro or in vivo pretreatment with thymosin alpha 1 (TA1). The results of this study indicate that pretreatment in vitro (100 ng/ml for 1 hr) or in vivo (200 micrograms/kg/day for 4 days) with thymosin alpha 1 (TA1), significantly increased the IL-2 (from 100 to 500 U/ml) in vitro induced cytotoxic activity of spleen lymphocytes, collected from both normal and cyclophosphamide and tumor-suppressed animals, against both YAC-1 (NK sensitive) and MBL-2 (NK resistant) cell lines. The potential use in combination of these two different biological response modifiers, useful in enhancing the immunological responses to IL-2 of lymphocytes, may provide a novel model of immunotherapeutic intervention in cancer.

Thymopentin and interleukin-2 in combination with 5-fluorouracil and leucovorin in metastatic colorectal adenocarcinoma: preliminary results

Thymic hormones have been shown to exhibit immunorestorative effects in vivo and in vitro, and to enhance the expression of high affinity interleukin-2 (IL-2) receptors on normal human lymphocytes stimulated with phytohemagglutinin. Based on these data, a clinical trial was initiated to determine the effects of the combination of 5-fluorouracil (5-FU) and folinic acid (FA) with thymopentin (TP-5) and interleukin-2 (IL-2) in patients with advanced colorectal carcinoma. Fifteen patients were treated with FA, 200 mg/m2/day by IV bolus, and 5-FU, 400 mg/m2/day as a 30-minute infusion, both given for 5 consecutive days every 28 days. TP-5, 50 mg/day, was administered subcutaneously on days 8-11, and IL-2, 9 million IU/m2 twice daily, was given subcutaneously on days 12-16. Of 8 patients evaluable for response, 4 achieved a response. Two patients had stable disease, and two progressed during treatment. There were no instances of life-threatening toxicity. Two patients developed grade III stomatitis and diarrhea followed by leukopenia and fever, requiring hospitalization. Other toxicities were moderate. These results are only preliminary, and a larger number of patients and longer follow-up are needed to draw meaningful conclusions about the merits of this new approach in cancer treatment.