Defective expression of IL-2 receptors on peripheral blood lymphocytes from patients with cluster headache.

In a previous study we demonstrated that cluster headache (CH) patients present an increased Natural Cytotoxic response after incubation of their peripheral blood lymphocytes (PBL) with Interleukin-2 (IL-2). This phenomenon led to an investigation of the phenotypic expression of PBL before and after IL-2 incubation, and of the IL-2 lymphocyte receptor. IL-2 receptor is expressed on T-lymphocytes activated with an high-affinity binding site. The analysis of the function of human IL-2 receptor was facilitated by the production of a specific monoclonal antibody (MAb). This MAb identifies the IL-2 receptors by blocking the binding of radiolabelled IL-2 to T-cells. In addition, we studied the expression of Leu-4, specific for T-cells; of Leu-11b, specific for FC receptor on NK cells; and the Transferrin Receptor, specific for lymphoblasts and monocytes. Twenty-three episodic CH patients were selected for this study. Ten sex and age-matched healthy volunteers were used as the control group. We evaluated the PBL phenotypic expression of cells subsets before incubation with IL-2 (1,000 I.U./ml) and after 72 hours. The following Becton Dickinson MAbs have been used: anti-Leu-4 (CD3), anti-IL-2 receptors (CD25), anti-Transferrin receptor (TFR) and anti-Leu-11b (CD16). Indirect fluorescence with a Becton Dickinson FACS-420 flow cytometer was used to analyze the cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphokine-activated killer (LAK) cell phenomenon in cluster headache. "In vitro" activation by recombinant interleukin-2.

Previous studies showed that the Natural Killer (NK) activity of peripheral blood lymphocytes (PBL) from cluster headache (CH) patients is lower than that of controls. This decreased activity seems to be independent of the cluster period. beta-interferon has been shown to be more effective in increasing NK activity when incubated with PBL from CH patients, than with PBL from control donors. Lymphokine-Activated Killer (LAK) cells can be generated by incubation of human PBL in recombinant Interleukin-2 (rIL-2). This phenomenon was studied in 10 CH patients and 8 healthy volunteers. PBL were activated to LAK cells by "in vitro" incubation for 72 hours in Control Medium containing rIL-2 (1000 I.U./ml). A four hour Chromium 51 release was used to measure LAK Cell Killing of K562 target cells. The released radioactivity was measured in a gamma scintillation counter. The CH patients showed a marked increase of LAK generation compared to control subjects. This effect seems to be augmented during the cluster period.

MicroELISA detection of thymosin alpha 1 released in thymic organ cultures.

Using a polyclonal specific rabbit anti-thymosin alpha 1 a highly sensitive enzyme-linked immunosorbent assay (ELISA) has been developed to measure thymosin alpha 1. Production of thymosin alpha 1 was detected in both thymic organ cultures and in mouse serum. The method is rapid (5 h), reproducible and easy to perform.

In vitro interactions of serotonin (5-HT) with mononuclear cells from migraine patients: alterations related to the phase of the attack.

Serotonin (5-HT) binds in a saturable and specific manner to high affinity binding sites present on the surface of human mononuclear cells. The serotonin binding to mononuclear cells has been assayed in patients with migraine, during and outside the crisis period. In these patients, unlike the episodic cluster headache patients that show a constant trend, the results are variable. This variability may depend on the fluctuation of 5-HT levels in the blood, during and after the crisis. A possible explanation for these observations is that at the beginning of the crisis the binding of 5-HT is still similar to the normal level. As the crisis goes on, there is at first an increase in 5-HT binding that saturates all the available sites and a subsequent phenomenon of desensitization, with a loss of high affinity sites. Further investigations are needed in order to assess whether or not the mononuclear cell functions are affected by the modifications of the binding of 5-HT, thought to be a regulatory molecule.

In vitro effect of thymosin alpha 1 on the expression of peanut agglutinin binding by murine thymocytes.

Thymosin alpha 1 induces the loss of PNA binding ability by subpopulation of thymic cells. This loss is probably due to an endocytic process. Nevertheless this disappearance is not a permanent one, suggesting a recycling of the PNA binding molecule. The cells that modulate their PNA binding sites after exposure to Thymosin alpha 1 are a small proportion of the total PNA+ thymocytes, indicating that not all thymocytes are susceptible to the thymic hormone Thymosin alpha 1. Conversely the exposure of thymocytes to Thymosin alpha 1 induces the disappearance of the binding sites for this ligand without further recycling, behavior expected for the receptor of a regulatory ligand. These results also indicate that the Thymosin alpha 1 and the PNA binding sites are on different molecules on the surface of the PNA+ thymocytes.

Effect of thymulin on intracellular cyclic nucleotides and prostaglandins E2 in peanut agglutinin-fractionated thymocytes.

Prostaglandin E2 (PGE2) and other selected agents which elevate intracellular cyclic AMP (cAMP) levels have been demonstrated to induce the appearance of surface markers in immature T lymphocytes. Thymic hormones, which are the natural inducers of these markers, have long been hypothesized to act through the increase of cAMP levels. We have approached this area of investigation by studying the effects of thymulin (a serum thymus-derived factor, coupled with Zinc) on intracellular cAMP and cyclic GMP (cGMP) levels (expressed as cAMP/cGMP ratio) and on the release of PGE2 in different thymocyte subpopulations. Thymocytes were fractionated by the peanut agglutinin (PNA) technique into cortical immature PNA+ and medullary mature PNA- thymocytes. The data presented in this report show that thymulin is able to increase the cAMP/cGMP ratio in PNA+ and in unfractionated thymocytes, depending on its concentration, but not in PNA- thymic cells. Conversely, it is able to increase the release of PGE2 by PNA- thymocytes but not by PNA+ and unfractionated thymic lymphocytes. These results are consistent with the hypothesis that thymulin could act through different mechanisms depending on the differentiation stage of its target cells. In fact, it could be suggested that immature T cells could be activated by thymulin thereby increasing the cAMP/cGMP ratio, whereas more mature T cells would be further differentiated by thymulin through enhanced release of PGE2.

Receptors for thymosin alpha 1 on mouse thymocytes.

Thymosin alpha 1 is able to act in vitro to stimulate T-cell precursors and to induce surface markers. The initial mechanism by which alpha 1 activates T cells could be the binding of alpha 1 to cell membranes. Using a specific anti-alpha 1 antibody and an indirect immunofluorescence procedure it was found that thymosin alpha 1 binds to the surface of a large portion of murine lymphocytes. Furthermore, thymocytes have been fractionated into immature and mature subpopulations by using the peanut agglutinin (PNA) technique. It was found that PNA+, immature cells showed specific receptors for alpha 1 on the cell membrane.

Modulation of natural killer activity by thymosin alpha 1 and interferon.

A single injection of alpha beta-interferon (alpha beta-IFN) (30000 units/mouse), a major biological modifier of natural killer (NK) cytolytic activity, strongly stimulated NK activity in normal mice, as expected, while the same treatment did not statistically alter the NK response in cyclophosphamide (CY)-suppressed animals. We investigated the possibility of thymosin alpha 1 cooperating with alpha beta-IFN in boosting NK activity in CY-suppressed animals. The results show that treatment with thymosin alpha 1 (200 micrograms/kg) for 4 days, followed by a single injection of alpha beta-IFN 24 h before testing, strongly restored NK activity in CY-suppressed mice. Thymosin alpha 1 was, moreover, able to accelerate the recovery rate of NK activity in bone marrow reconstituted murine chimeras. Taken together the data support the concept that the synergic effect between thymosin alpha 1 and alpha beta-IFN could be the result of effects on differentiation of the NK lineage at different levels.

Modulation of endogenous prostaglandins by thymosin-alpha 1 in lymphocytes.

The effects of thymosin-alpha 1 on the stimulation of specific release of prostaglandin E2 (PGE2) from splenic lymphocytes and thymocytes were studied. Experiments were also performed to study in parallel the absolute levels of thymosin-alpha 1 in the blood and the induction of serum FTS activity and of azathioprine sensitivity of spleen cells from adult thymectomized (ATx) mice. A significant difference in the release of PGE2 between normal splenocytes and splenocytes from ATx mice was observed. Thymosin-alpha 1 at certain concentrations was able to stimulate PGE2 release from lymphocytes of ATx mice while inhibiting release in lymphocytes of normal mice. Also, thymocytes were stimulated to release PGE2 after incubation with alpha 1 in a manner similar to that seen in spleen cells of ATx mice. Approximately the same concentrations of alpha 1 was found to also correct the low azathioprine sensitivity of splenocytes from ATx mice. Determinations of FTS-like activity in the blood and the pharmacokinetics of alpha 1 after administration of this synthetic molecule show a clear dissociation. A maximum peak of alpha 1 activity was obtained after 1 hr, while maximal FTS-like activity was observed after 24 hr. The inhibition of the induction by alpha 1 of FTS-like activity and of Thy 1.2 antigen by indomethacin suggests that the action of alpha 1 requires prostaglandin biosynthesis.

Is thymosin action mediated by prostaglandin release?

Treatment of spleen cells derived from adult thymectomized mice with thymosin fraction 5 resulted in a rapid and dose-dependent stimulation of the release of immunoreactive prostaglandin E2. The release of prostaglandin E2 was associated with induction of theta antigen and was totally inhibited by indomethacin. In contrast, prostaglandin E2 release from spleen cells from intact donors was inhibited by treatment with fraction 5. The data support the concept that prostaglandin E2 mediates the effects of thymosin fraction 5 on lymphocytes.

Decreased serum thymic factor activity in asthmatic children.

Serum thymic factor (STF) activity was assayed in 26 young asthmatic patients and in 20 age-and sex-matched controls, in view of the increasing importance attributed to this thymic product in regulating several immune mechanisms. Determinations of total and specific IgE and of other immunoglobulins and skin tests were also performed. Decreased STF activity and high total and specific IgE concentrations were observed in the majority of asthmatic patients. In controls, STF activity was within normal limits in all cases and total and specific IgE concentrations were increased only on one case. The decreased STF activity may be responsible for a possible impairment of cell-mediated immunity and for the increased stimulation of the reaginic system observed in asthmatic patients, via its effects on some T cell subpopulation, namely, suppressor T lymphocytes, which seem particularly sensitive to STF variations. On the basis of these data and of the results of our study, a possible, although speculative, correlation between reduced STF activity and high IgE concentrations in asthmatic patients may be postulated. The reported increased occurrence of autoimmune phenomena in asthmatic patients is in agreement with the hypothesis of a STF-mediated suppressor T-lymphocyte quantitative and/or qualitative defect in this disease.

Effects of antithymic reticuloepithelial cells serum on the levels of circulating thymic factor and on the sensitivity to azathioprine of spleen spontaneous rosette-forming cells.

Swiss mice treated with an antithymic reticuloepithelial cells serum (ATRES) showed a drastic and prolonged depression of the serum thymic factor. A similar but less pronounced effect was also observed following the administration of the antithymocyte (ATS) and the antilymphocyte (ALS) sera. Conversely, the azathioprine sensitivity of spleen spontaneous rosette-forming cells was highly modified by the ATRES but not by the ATS or the ALS. The probable mechanisms of such effects are discussed.