Sabrina Brenci

Increased level of serum HLA class I antigens in HIV infection correlation with disease progression

Analysis of (sHLA-I) antigens in a large number of HIV-positive subjects found a significant increase of their level, but did not detect any change in their molecular profile. Monitoring at yearly intervals for four years of the sHLA-I antigen level in 14 HIV-positive subjects with a normal sHLA-I antigen level at study entry showed a significant correlation between progressive increase of sHLA-I antigen level and disease progression. Furthermore, a Kaplan-Meier plot of the frequency of development of AIDS in 34 patients whose cases were followed for 7 years showed that sHLA-I antigen level is a strong predictor of progression to AIDS. Its predictive value is comparable to that of serum beta 2-mu level, greater than that of serum neopterin, and lower than that of CD4+ T-cell percentage. The predictive value of sHLA-I antigen level in combination with serum beta 2-mu level, neopterin level, or CD4+ T-cell percentage is greater than that of each individual variable. These results suggest that measurement of the sHLA-I antigen level may provide useful prognostic information in HIV-positive subjects.

HLA class-I-soluble antigen serum levels in liver transplantation : a predictor marker of acute rejection

The serum levels of sHLA-I have been determined in 16 patients following liver transplantation. sHLA-I levels did not show remarkable variations in six patients without evidence of transplant-related complications. sHLA-I levels strongly increased in 10 patients undergoing acute rejection episodes. In these patients, an average 20% daily increase of sHLA-I levels was detected on the 6 days preceding and on the 2 days following the rejection episode. A fast decrease of sHLA-I levels was observed in seven patients following treatment of acute rejection with anti-CD3 mAb. The serum level of sHLA-I antigens positively correlated with ALT serum level and inversely correlated with PT. The determination of sHLA-I in serum may therefore be proposed as a useful marker in the monitoring of patients following liver transplantation. The increase of sHLA-I antigens may predict the onset of acute rejection whereas their decrease may be related to a good response of acute rejection to immunosuppressive treatment.

SOLUBLE HLA CLASS I AND CLASS II MOLECULE LEVELS IN SERUM AND CEREBROSPINAL FLUID OF MULTIPLE SCLEROSIS PATIENTS

Abstract Increased concentrations of soluble HLA class I and class II molecules (sHLA-I and sHLA-II) have been observed in infectious, inflammatory, and autoimmune diseases. Because autoimmune mechanisms are considered to play a role in the pathogenesis of multiple sclerosis (MS), we decided to dose sHLA-I and sHLA-II in serum and cerebrospinal fluid (CSF) of MS patients comparing their concentrations with those observed in serum and CSF of patients with other neurologic diseases (OND) without evidence of neuroradiologic involvement of central nervous system (CNS) and in serum of healthy donors. The serum concentrations of sHLA-I were higher in both MS and OND patients than in healthy donors (P < 0.05) whereas sHLA-II serum concentrations were lower in MS patients than in both OND patients and healthy donors (P < 0.01). Detectable amounts of sHLA-II were observed in the CSF of 45% of MS patients and in CSF of only 6% of OND patients (P < 0.001). In MS patients a significant correlation between sHLA-I serum and CSF concentrations was observed (P < 0.01), whereas sHLA-II serum and CSF levels did not correlate. In conclusion, alterations of sHLA-I and sHLA-II serum and CSF concentrations are present in MS patients and could be involved in the induction of enhanced susceptibility to develop MS or in MS pathogenesis.

Behavior of soluble HLA class I antigens in patients with chronic hepatitis C during interferon therapy: An early predictor marker of response?

Soluble HLA class I antigens (sHLA-I),β2-microglobulin (β2-μ.) and alanine aminotransferase (ALT) serum levels have been evaluated in 16 patients affected by chronic hepatitis C treated for six months with recombinant interferon-α (rIFN-α, 3 MU three times a week). The predictor role of sHLA-I and ALT modifications with respect to the response to rIFN-α therapy was also evaluated. Six patients responded (group 1), five patients relapsed following an initial response (group 2), and five did not respond to rIFN-α treatment (group 3). The baseline serum levels of sHLA-I andβ2-μ were significantly higher in all three groups of HCV-positive patients with respect to HCV-negative controls (P<0.05). A significant increase of sHLA-I serum level with respect to baseline value (P<0.001) was observed in group 1 patients after two weeks of rIFN-α treatment. sHLA-I serum level then decreased, although remaining steadily and significantly increased with respect to baseline (P values ranging from 0.05 to 0.01) in the following five months and then returned to baseline one month after the end of rIFN-α administration. No significant variations ofβ2-μ serum levels were detected throughout the observation period. In group 1 patients ALT serum levels significantly decreased after two weeks of rIFN-α treatment (P<0.001) and then remained in the normal range throughout the observation period. In the other two groups of patients no relevant variations of sHLA-I andβ2-μ serum levels were found during and after rIFN-α therapy. The modifications of sHLA-I serum levels discriminate, as a single marker, group 1 patients from group 2 and 3 patients after two weeks of rIFN-α treatment (P<0.003). The association of sHLA-I and ALT modifications improves the discriminant power and leads to a complete differentiation of the three groups of patients after four weeks of rIFN-α treatment (P<0.0001). If confirmed in a larger series of patients, these results will provide a useful marker to predict which patients affected by chronic hepatitis C will respond to treatment and will help to avoid their ineffective treatment with an expensive and potentially harmful drug.

L-TYROSINE AND NICOTINE INDUCE SYNTHESIS OF L-DOPA AND NOREPINEPHRINE IN HUMAN LYMPHOCYTES

Catecholamines (CA) were studied in peripheral human lymphocytes in basal conditions as well as after L-tyrosine and/or acetylcholine (ACh) stimulation. Nicotinic and muscarinic receptor activation and blockade were assessed. CA were determined after ultrasonic cell disruption in peripheral lymphocytes after incubation (1 h at 37 degrees C) with the chemicals employed. L-tyrosine significantly increased (P < 0.01) L-Dopa and norepinephrine (NE) content of lymphocytes. ACh in the low microM range did not modify, whereas ACh (60 microM) and (120 microM) significantly increased (P < 0.01), both L-Dopa and NE intracellular levels. L-tyrosine plus ACh (60 microM) or (120 microM) significantly increased (P < 0.01) intracellular L-Dopa and NE versus control, versus L-tyrosine alone and versus ACh alone. The increase was higher than the algebraic sum of the individual increases. Nicotine (250 microM), but not muscarine (50 microM), significantly increased L-Dopa and NE in lymphocytes. Tetraethylammonium (500 microM) (nicotinic blocker), but not atropine (100 microM) (muscarinic blocker), inhibited the ACh-mediated increase of intracellular L-Dopa and NE. These data show that lymphocyte synthesis of CA is under nicotinic control. Since intracellular L-Dopa after L-tyrosine plus ACh increased 6-fold versus basal, 2-fold versus L-tyrosine alone and 3-fold versus ACh alone, it is concluded that ACh might regulate CA synthesis in lymphocytes through an activation of the rate limiting enzyme tyrosine hydroxylase.

Soluble HLA class I/CD8 ligation triggers apoptosis in EBV-specific CD8+ cytotoxic T lymphocytes by Fas/Fas-ligand interaction.

In the present study, we report that allogeneic soluble HLA class I (sHLA-I) molecules isolated from serum induce apoptosis on EBV-specific CD8(+) Fas(+) cytotoxic T lymphocytes (CTL). CTL apoptosis is induced by the binding of sHLA-I molecules to CD8 and its extent depends on the time of incubation with sHLA-I molecules. Apoptosis is triggered by the interaction of Fas(+) CTL with soluble Fas-ligand, which is released following the binding of sHLA-I antigens to CD8 molecules. These results suggest that sHLA-I molecules may regulate immune responses by inducing apoptosis in virus-specific CTL.

Soluble HLA Class I and Fas Ligand Molecules in Blood Components and their Role in the Immunomodulatory Effects of Blood Transfusions

It has been known for many years that blood transfusions may have immunomodulatory effects, however an ultimate explanation of this phenomenon is lacking. In the present paper we report that the concentrations of soluble HLA class I (sHLA-I) and soluble Fas ligand (sFasL) molecules in supernatants of blood components which contain elevated numbers of residual donor leukocytes, like red blood cells and random-donor platelets, are significantly higher than in other blood components. Elevated amounts of sFasL molecules are also found in some commercial immunoglobulin preparations. sHLA-I and sFasL molecules in blood components and in immunoglobulin preparations are biologically active in vitro as they inhibit mixed lymphocyte responses and cytotoxic T cell activity in allogeneic and autologous combinations and induce apoptosis in Fas-positive cells. If these results are paralleled in vivo the amount of sHLA-I and sFasL molecules should be taken into account in clinical practice in order to select the blood component and the immunoglobulin preparation which could induce the desired immunomodulatroy effect in the recipient.

ACETYLCHOLINE-INDUCED, CALCIUM-DEPENDENT NOREPINEPHRINE OUTFLOW FROM PERIPHERAL HUMAN LYMPHOCYTES

Catecholamines (CA) were studied in peripheral human lymphocytes, as well as in the supernatants, after incubation with L-tyrosine and L-dihydroxyphenylalanine (L-Dopa) for 1 h. The effect that the addition of acetylcholine (ACh), Veratridine, lonomycin or KCI had on the outflow of norepinephrine (NE) from lymphocytes was also studied. The effect of the addition of methoxyverapamil (D600, a Ca2+ channel blocker) and cholinergic antagonists had on the ACh-induced NE outflow was assessed. CA were determined by HPLC-ECD, both in the supernatant and in the cell lysates. L-Tyrosine and L-Dopa significantly (P < 0.01) increased intracellular NE. Neither L-tyrosine, L-Dopa, nor vehicle induced a detectable outflow of NE to the supernatants. ACh [120 microM], Veratridine [100 microM], Ionomycin [10 microM] and KCl [50 mM] (with or without the simultaneous addition of L-tyrosine or L-Dopa) all induced a detectable outflow of NE to the supernatant when added 5 min before the end of incubation. NE was not detectable in the supernatant when the chemicals were added 10 to 20 min before the end of the incubation. When the chemicals were added at lower concentrations, erratic secretion or no secretion whatsoever was observed. D600 [100 microM] was able to significantly (P < 0.01) reduce the ACh-induced NE outflow. Tetraethylammonium (nicotinic antagonist), but not atropine (muscarinic antagonist), significantly (P < 0.001) decreased the ACh-induced NE outflow. The outflow of NE from peripheral human lymphocytes was seen. NE secretion seems to be ACh- and calcium-dependent since Veratridine, Ionomycin and KCl are able to induce Ca2+ entry by means of various mechanisms. The Ca2+ channel blocker employed in this study (D600) reduced the ACh-dependent NE outflow. We can conclude that both ACh (through nicotinic receptors) and calcium are involved in the outflow of NE from peripheral human lymphocytes.

Soluble β2-μ-Associated and β2-μ-Free HLA class I heavy chain serum levels in interferon-α nonresponder chronic hepatitis C patients. Markers of immune activation, and response to antiviral retreatment

The serum levels of soluble β2-μ-associated and β2-μ-free HLA class I heavy chains were determined in 28 interferon-α nonresponder chronic hepatitis C patients retreated with interferon-α plus ribavirin and in 70 healthy subjects. The baseline levels of β2-μ-associated and β2-μ-free HLA class I heavy chains were significantly higher in patients than in healthy controls(P = 0.001). The levels of β2-μ-associated HLA class I heavy chains significantly increased in responder patients with respect to nonresponders at the third month of treatment(P = 0.03). At the sixth month of treatment and after 6 months of follow up the levels of β2-μ-associated HLA class I heavy chains decreased in responder patients and increased in nonresponders. The levels of β2-μ-free HLA class I heavy chains showed only minor changes during and after treatment. We suggest that the determination of hepatitis C virus RNA levels combined with soluble β2-μ-associated HLA class I heavy chains, as a marker of immune activation, could identify interferon-α non responder chronic hepatitis C patients most likely to respond to a retreatment with interferon-α plus ribavirin.

Monitoring of Serum HLA Class I Antigen Levels in Allogeneic Bone Marrow Transplantation

The levels of serum HLA Class I antigens were determined at weekly intervals up to five weeks in thirty-eight patients who had undergone allogeneic BMT. In patients with GVHD grade I serum HLA Class I antigen levels did not change during the observation period. In patients with GVHD grade II – IV serum HLA Class I antigen level increased in the week before the onset of GVHD and was maximal during the GVHD episode. The mean ± SEM concentrations of serum HLA Class I antigens during GVHD grade II – IV episodes (6.3 ±1.1 jig/ml) is significantly higher than in the first week after BMT (2.5 ± 0.3 lng/ml) and in the week preceding the GVHD episode (3.5 ± 0.4 ug/ml) (P = 0.0002 and P = 0.01, respectively). The results of the present investigation suggest that measure of serum HLA Class I antigen level may be a useful marker to detect an acute GVHD following BMT.