Inhibition of DNA synthesis in peripheral blood mononuclear cells treated with phosphatidylserines containing unsaturated acyl chains.

The immunosuppressive action of phosphatidylserine has been studied in mitogen-activated human peripheral blood mononuclear cells. The addition of phospholipid (10-60 nmol/10(6) cells) causes a dose-dependent inhibition of DNA synthesis induced by PHA, anti-CD3 mAb, allogeneic lymphocytes and tetradecanoylphorbol acetate plus ionomycin. In contrast, the interleukin-2-dependent DNA synthesis is less affected. Flow cytometric analysis and binding of radioiodinated interleukin-2 show that the phospholipid prevents the expression of interleukin-2 and transferrin receptors. Removal of monocytes by adherence does not change the action of phosphatidylserine. Furthermore, the phospholipid is equally effective in preparations depleted of CD4+ or CD8+ lymphocytes. Phosphatidylinositol partly reproduces the action of phosphatidylserine. Phosphatidic acid, phosphatidylglycerol and phosphatidylcholine are inactive. Also unsaturated phosphatidylserine analogues inhibit DNA synthesis whereas saturated phosphatidylserines do not. The data suggest that phosphatidylserine mainly affect the steps of T cell activation preceding the production of interleukin-2 and the expression of its receptor. The phosphorylserine headgroup and the unsaturated acyl chains contribute to this effect.     

An ATP-activated channel is involved in mitogenic stimulation of human T lymphocytes

We investigated the effect of pharmacologic modulation of the ATP receptor on intracellular ion changes and proliferative response of human peripheral blood lymphocytes (PBLs) and purified T lymphocytes. Extracellular ATP (ATPe) triggered in these cells an increase in the cytoplasmic Ca2+ concentration ([Ca2+]i) and plasma membrane depolarization. Whereas both Ca2+ release from intracellular stores and influx across the plasma membrane were detected in the whole PBL population, only Ca2+ influx was observed in T cells. In the presence of near physiologic extracellular Na+ concentrations (125 mmol/L), Ca2+ permeability through the ATPe-gated channel was very low, suggesting a higher selectivity for monovalent over divalent cations. The selective P2Z agonist benzoylbenzoic ATP (BzATP) increased [Ca2+]i in the presence but not the absence of extracellular Ca2+ and also caused plasma membrane depolarization. The covalent blocker oxidized ATP (oATP), an inhibitor of P2X and P2Z receptors, prevented Ca2+ influx and plasma membrane depolarization, but had no effect on Ca2+ release from stores. Stimulation with ATPe alone had no significant effects on PBL 3H-thymidine incorporation. On the contrary, ATPe or BzATP had a synergistic effect on DNA synthesis stimulated by selective T-cell mitogens such as phytohemagglutinin, anti-CD3 monoclonal antibody, or allogenic PBLs (mixed lymphocyte cultures). Treatment with oATP inhibited mitogenic stimulation by these receptor-directed agents but not by the combined application of the Ca2+ ionophore ionomycin and phorbol myristate acetate. Interleukin-2 partially relieved inhibition by oATP. These results suggest that human T lymphocytes express a plasma membrane channel gated by ATPe that is involved in mitogenic stimulation.     

Presence of detectable levels of soluble HLA-G molecules in CSF of relapsing-remitting multiple sclerosis: relationship with CSF soluble HLA-I and IL-10 concentrations and MRI findings

We have investigated the presence of non-classical soluble HLA-G molecules (sHLA-G) in cerebrospinal fluid (CSF) of multiple sclerosis (MS) patients and the possible relationships between CSF levels of sHLA-G, classical soluble HLA-I (sHLA-I) molecules, IL-10 amounts and Magnetic Resonance Imaging (MRI) findings were evaluated. We studied by ELISA technique the sHLA-I, sHLA-G and IL-10 levels in CSF of 50 relapsing-remitting (RR) MS patients stratified according to clinical and MRI evidence of disease activity. Thirty-six patients with other inflammatory neurological disorders (OIND) and 41 with non-inflammatory neurological disorders (NIND) were used as controls. CSF mean levels were significantly higher in MS and OIND than in NIND for sHLA-I (p<0.001) and in MS than in controls for sHLA-G (p<0.001), with no differences among the various groups for IL-10 mean concentrations. An increase in CSF sHLA-I was found in MS patients with Gd-enhancing lesions (p<0.01), while sHLA-G and IL-10 were more represented in MS patients without lesional activity on MRI scans (p<0.02). In MRI-inactive MS, CSF IL-10 mean concentrations were significantly greater in patients with CSF-detectable levels of sHLA-G than in those without any evidence of CSF sHLA-G expression (p<0.05). Our findings suggest that CSF classical sHLA-I and non-classical sHLA-G levels may modulate MS activity as assessed by MRI acting in opposite directions. The association observed between sHLA-G and IL-10 when Gd-enhancing lesion resolved indicates a potential immunoregulatory role for IL-10 in the control of MS disease activity by shifting the sHLA-I/sHLA-G balance towards sHLA-G response.     

Blood donation leads to a decrease in natural killer cell activity: a study in normal blood donors and cancer patients

Transfusion-induced immunosuppression has long been known to be beneficial for organ transplantation patients, but recent retrospective studies suggest that blood transfusions may be detrimental for patients with cancer. If autologous blood is used to avoid immunosuppression, the assumption is that the procedure, involving blood donation, is immunologically neutral. In the present study, this assumption was evaluated by monitoring 33 normal blood donors and 16 colorectal cancer patients before and after donation of 1 (500 mL) and 2 units of blood, respectively. The cancer patients belonged to the autologous arm of a randomized trial in which the effects of allogeneic versus autologous blood on cancer prognosis were studied. The patients donated 2 units of blood with an interval of 3 to 4 days between donations. Flow cytometric analysis revealed that blood donation by normal donors and cancer patients had no effect on the proportion of B, T, and natural killer (NK) cells. Only the total number of lymphocytes was significantly decreased in the normal donors on Day 12 after donation. Blood donation had no significant effect on T-cell function assessed by phytohemagglutinin stimulation in normal donors or in cancer patients donating 2 units of blood. A significant depression of NK cell function (88% and 74% of predonation levels) was observed in normal donors on Days 2 and 5 after donation; on Day 12, the activity was again normal. Colorectal cancer patients had a significantly depressed NK cell activity (54% of predonation activity) on Day 12 after the first donation.(ABSTRACT TRUNCATED AT 250 WORDS)     

CSF levels of soluble HLA-G and Fas molecules are inversely associated to MRI evidence of disease activity in patients with relapsing-remitting multiple sclerosis

Cerebrospinal fluid (CSF) concentrations of soluble human leukocyte antigen class I (HLA-I) (sHLA-I), HLA-G (sHLA-G) and anti-apoptotic Fas (sFas) molecules were measured by enzyme linked immunosorbent assay technique in 65 relapsing-remitting (RR) MS patients classified according to clinical and magnetic resonance imaging (MRI) evidence of disease activity. Sixty-four patients with other inflammatory neurological disorders (OIND) and 64 subjects with noninflammatory neurological disorders (NIND) served as controls. CSF concentrations were higher in RRMS and in OIND than in NIND patients for sHLA-I (P < 0.02), greater in RRMS than in OIND and in NIND for sHLA-G (P < 0.001 and P < 0.01, respectively) and lower in RRMS than in OIND and in NIND for sFas (P < 0.001 and P < 0.02, respectively). An increase in CSF levels was identified in MRI active RRMS for sHLA-I (P < 0.01) and in MRI stable RRMS for sHLA-G (P < 0.01), whereas CSF values of sFas were decreased in RRMS without Gd-enhancing lesions (P < 0.02). In MS patients with no evidence of MRI disease activity, a trend towards an inverse correlation was found between CSF concentrations of sHLA-G and sHLA-I and between CSF levels of sHLA-G and sFas. Our results indicate that enhanced CSF levels of sHLA-I antigens most likely represent an indirect manifestation of intrathecal immune activation taking place in neuroinflammation. Conversely, reciprocal fluctuations in CSF sHLA-G and sFas levels observed when MRI disease activity resolved suggest that sHLA-G could play an immunomodulatory role in MS through Fas/FasL-mediated mechanisms.