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In the present study, we have evaluated the apoptotic effect of soluble human MHC class I (sHLA-I) antigens on CD8⁺ T lymphocytes. sHLA-I antigens and β₂-microglobulin-free HLA class I heavy chains, isolated from serum, induced apoptosis on phytohemagglutinin-activated CD8⁺ T lymphocytes in autologous and allogeneic combinations. The extent of CD8⁺ T cell apoptosis depends on the degree of activation, time of incubation with sHLA-I antigens and amount of sHLA-I antigens added to the cultures. Apoptosis is induced by the interaction of Fas (CD95)⁺ cells with soluble Fas ligand which is released following binding of sHLA-I antigens to CD8 molecules. These results suggest that sHLA-I antigens may regulate immune responses by inducing apoptosis in activated CD8⁺ T cells.

In the present study, we have evaluated the apoptotic effect of soluble human MHC class I (sHLA-I) antigens on CD8(+) T lymphocytes. sHLA-I antigens and beta(2)-microglobulin-free HLA class I heavy chains, isolated from serum, induced apoptosis on phytohemagglutinin-activated CD8(+) T lymphocytes in autologous and allogeneic combinations. The extent of CD8(+) T cell apoptosis depends on the degree of activation, time of incubation with sHLA-I antigens and amount of sHLA-I antigens added to the cultures. Apoptosis is induced by the interaction of Fas (CD95)(+) cells with soluble Fas ligand which is released following binding of sHLA-I antigens to CD8 molecules. These results suggest that sHLA-I antigens may regulate immune responses by inducing apoptosis in activated CD8(+) T cells.

The immunomodulatory effect of allogeneic blood transfusions (ABT) has been known for many years. However, a complete understanding of the effects of ABT on the recipient’s immune system has remained elusive. Soluble HLA class I (sHLA-I), HLA class II (sHLA-II), and Fas ligand (sFasL) molecules may play immunoregulatory roles. We determined by double-determinant immunoenzymatic assay (DDIA) sHLA-I, sHLA-II, and sFasL concentrations in different blood components. sHLA-I and sFasL levels in red blood cells (RBCs) stored for up to 30 days and in random-donor platelets are significantly (P?

Objectives. The main aim was to analyse the long-term therapeutic effects on systemic sclerosis (SSc) patients of treatment with either (i) iloprost alone or (ii) low-dose oral cyclosporin A (CyA) associated with iloprost. A secondary aim was to analyse interleukin-6 (IL-6) serum levels in SSc patients before and after 1 yr of treatment.Methods. A clinical trial was performed in which 20 consecutive SSc patients were alternately randomized into two homogeneous groups receiving either monthly i.v. iloprost (1 ng/kg/min in 6 h i.v. infusion, for 5 consecutive days, 1 week per month) (Group I) or low-dose CyA (2.5 mg/kg/day) associated with iloprost administration (Group II). IL-6 concentrations were evaluated by ELISA in the sera of each patient before and after 1 yr of therapy and in 20 healthy subjects.Results. After 1 yr of therapy, a significant improvement of skin (P=0.008), microvascular (P=0.004) and oesophageal (P=0.05) morphological and functional parameters was observed only in Group II patients. Furthermore, after 1 yr of treatment, a significant reduction (P=0.007) of IL-6 serum concentration was observed only in Group II patients.Conclusions. Collectively, our data suggest that the combination of low-dose CyA with iloprost administration may be of clinical utility in SSc and that a mechanism of action of CyA in SSc may include the decrease in IL-6 production.

Different glucocorticoid hormones (GCH) show differences in the intensity and in the kinetics of their immunomodulating activity. The mechanism(s) of action of GCH is under investigation, but is has been noted that they exert immune activity via the genomic pathway. We have studied the effects of prednisone (PDN), deflazacort (DFC), and dexamethasone (DXM) on the production of cytokines (IL-2, IL-6, TNF-?, IL-10) by peripheral T lymphocytes, and the effects on the inhibition of NF-kB DNA binding activity by activated Jurkat cell line. The data obtained show that the three GCH molecules exert an immunosuppression on cytokine production by T lymphocytes and a strong decrease in the nuclear translocation of NF-kB in Jurkat cells; moreover, (a) not all the cytokines investigated were affected, and not with the same intensity, by the three GCH and (b) DXM inhibited the binding activity of NF-kB less than that of DFC and PDN. These data are in agreement with the concept that different GCH compounds might differ in their binding and affinity properties, tissue-specific metabolism, and interaction with transcription factor.

Glucocorticoid hormones (GCH) induce apoptosis in PHA-primed peripheral blood T lymphocytes (PBL) and down-regulate membrane-bound proteins involved in the immune response. We have analyzed whether GCH are able to affect the expression of the TCR-associated molecules CD3, CD4, and CD8 on PBL-PHA, and whether the modulation of those receptors is related to the GCH-driven apoptosis of the PBL-PHA. Lymphocytes were cultured with PHA or with PHA plus prednisone (PDN) 10?3, 10?6, and 10?9M. Then expression of CD2, CD3, CD4, CD8, and CD56 antigens was studied by cytofluorimetric assay using propidium iodide (PI) staining and annexin procedure, and by gel electrophoresis of low molecular weight DNA. PDN, at a pharmacological concentration (10?6M), was able to inhibit the CD3 expression on T cells. The kinetics of CD3 decrement and of apoptosis show that the down-regulation of CD3 molecules precedes DNA fragmentation and that the cells lacking CD3 are those prone to PDN-induced apoptosis. The inhibition of CD3 is not related to a transcriptional or posttranscriptional phenomenon, because both PBL-PHA and PBL-PHA-PDN expressed the same amount of intracytoplasmic CD3 molecule. PDN also induced a down-regulation of the CD4 and CD8 molecules that resulted sooner in more intense CD8. In vitroPDN is able to induce apoptosis in PBL-PHA through a down-regulation of CD3 molecules.

Objectives. The main aim was to analyse the long-term therapeutic effects on systemic sclerosis (SSc) patients of treatment with either (i) iloprost alone or (ii) low-dose oral cyclosporin A (CyA) associated with iloprost. A secondary aim was to analyse interleukin-6 (IL-6) serum levels in SSc patients before and after 1 yr of treatment.
Methods. A clinical trial was performed in which 20 consecutive SSc patients were alternately randomized into two homogeneous groups receiving either monthly i.v. iloprost (1 ng/kg/min in 6 h i.v. infusion, for 5 consecutive days, 1 week per month) (Group I) or low-dose CyA (2.5 mg/kg/day) associated with iloprost administration (Group II). IL-6 concentrations were evaluated by ELISA in the sera of each patient before and after 1 yr of therapy and in 20 healthy subjects.
Results. After 1 yr of therapy, a significant improvement of skin (P=0.008), microvascular (P=0.004) and oesophageal (P=0.05) morphological and functional parameters was observed only in Group II patients. Furthermore, after 1 yr of treatment, a significant reduction (P=0.007) of IL-6 serum concentration was observed only in Group II patients.
Conclusions. Collectively, our data suggest that the combination of low-dose CyA with iloprost administration may be of clinical utility in SSc and that a mechanism of action of CyA in SSc may include the decrease in IL-6 production.

We report that an antibody engineered to express three Arg‐Gly‐Asp (RGD) repeats in the third complementarity‐determining region of the heavy chain (antigenized antibody) efficiently inhibits the lysis of human erythroleukemia K‐562 cells by natural killer (NK) cells. Synthetic peptides containing RGD did not inhibit. Inhibition was specific for the (RGD)3‐containing loop and required simultaneous occupancy of the Fc receptor (CD16) on effector cells. The antigenized antibody inhibited other forms of cytotoxicity mediated by NK cells but not cytotoxicity mediated by major histocompatibility complex‐restricted cytotoxic T lymphocytes (CTL). A three‐dimensional model of the engineered antibody loop shows the structure and physicochemical characteristics probably required for the ligand activity. The results indicate that an RGD motif is involved in the productive interaction between NK and target cells. Moreover, they show that peptide expression in the hypervariable loops of an antibody molecule is an efficient procedure for stabilizing oligopeptides within a limited spectrum of tertiary structures. This is a new approach towards imparting ligand properties to antibody molecules and can be used to study the biological function and specificity of short peptide motifs, including those involved in cell adhesion.

We report that an antibody engineered to express three Arg‐Gly‐Asp (RGD) repeats in the third complementarity‐determining region of the heavy chain (antigenized antibody) efficiently inhibits the lysis of human erythroleukemia K‐562 cells by natural killer (NK) cells. Synthetic peptides containing RGD did not inhibit. Inhibition was specific for the (RGD)3‐containing loop and required simultaneous occupancy of the Fc receptor (CD16) on effector cells. The antigenized antibody inhibited other forms of cytotoxicity mediated by NK cells but not cytotoxicity mediated by major histocompatibility complex‐restricted cytotoxic T lymphocytes (CTL). A three‐dimensional model of the engineered antibody loop shows the structure and physicochemical characteristics probably required for the ligand activity. The results indicate that an RGD motif is involved in the productive interaction between NK and target cells. Moreover, they show that peptide expression in the hypervariable loops of an antibody molecule is an efficient procedure for stabilizing oligopeptides within a limited spectrum of tertiary structures. This is a new approach towards imparting ligand properties to antibody molecules and can be used to study the biological function and specificity of short peptide motifs, including those involved in cell adhesion.