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

The diagnostic effectiveness of serum sialic acid predicts both qualitative and quantitative prostate cancer in patients with prostate-specific antigen between 4 and 20 ng/mL

Introduction

This study aimed to evaluate the predictive value of the serum biochemical index, including alkaline phosphatase (AKP), lactate dehydrogenase (LDH), α-L-fucosidase (AFU), serum sialic acid (SA), and fibrinogen (FIB), for prostate cancer (PCa) and clinically significant prostate cancer (CSPCa) in patients with a prostate-specific antigen (PSA) value between 4 and 20 ng/mL.

Patients and methods

This study retrospectively examined the clinical data of 408 eligible patients who underwent prostate biopsies in our hospital between March 2015 and July 2022. CSPCa was defined as a "Gleason grade group of≥2". For analyzing the association between PCa/CSPCa and serum biochemical index, univariable logistic regression and multivariable logistic regression were conducted. Based on the multivariable logistic regression model, we constructed models and compared the area under the curve (AUC). We generated the nomogram, the ROC curve, the DCA curve, and the calibration curve for PCa.

Results

Overall, we studied 271 patients with PCa (including 155 patients with CSPCa) and 137 non-PCa patients. Patients with PCa were more likely to consume alcohol, have higher total PSA (TPSA) values, and have lower free PSA (FPSA) and free/total PSA (f/T) values. There were higher TPSA values and lower f/T values in the CSPCa group when compared with the non-CSPCa group. The univariate logistic regression analyses did not show significant results. However, AKP, AFU, SA, TPSA, and FPSA all retain significant significance when all factors are included in multifactor logistic regression analysis. This finding suggests that the exposure factor exhibited an independent effect on the outcome after controlling for other factors, including the potential confounding effects that may have been underestimated. Through ROC curves, we found that SA and TPSA levels are more powerful predictors. In contrast, there is a lack of excellent predictive value for PCA and CSPCa using Age, AFU, FIB, and FPSA.

Conclusion

In our study, serum biochemical index is a potential prediction tool for PCa and CSPCa for patients with PSA values between 4 and 20 ng/mL. Additionally, the new serum biochemical index SA is also useful when diagnosing PCa and CSPCa, as we conclude in our study.

Apoptosis and Phagocytosis as Antiviral Mechanisms

Viruses are infectious entities that make use of the replication machinery of their hosts to produce more progenies, causing disease and sometimes death. To counter viral infection, metazoan hosts are equipped with various defense mechanisms, from the rapid-evoking innate immune responses to the most advanced adaptive immune responses. Previous research demonstrated that cells in fruit flies and mice infected with Drosophila C virus and influenza, respectively, undergo apoptosis, which triggers the engulfment of apoptotic virus-infected cells by phagocytes. This process involves the recognition of eat-me signals on the surface of virus-infected cells by receptors of specialized phagocytes, such as macrophages and neutrophils in mice and hemocytes in fruit flies, to facilitate the phagocytic elimination of virus-infected cells. Inhibition of phagocytosis led to severe pathologies and death in both species, indicating that apoptosis-dependent phagocytosis of virus-infected cells is a conserved antiviral mechanism in multicellular organisms. Indeed, our understanding of the mechanisms underlying apoptosis-dependent phagocytosis of virus-infected cells has shed a new perspective on how hosts defend themselves against viral infection. This chapter explores the mechanisms of this process and its potential for developing new treatments for viral diseases.

Overexpression of ERAP2N in Human Trophoblast Cells Promotes Cell Death

The genes involved in implantation and placentation are tightly regulated to ensure a healthy pregnancy. The endoplasmic reticulum aminopeptidase 2 (ERAP2) gene is associated with preeclampsia (PE). Our studies have determined that an isoform of ERAP2-arginine (N), expressed in trophoblast cells (TC), significantly activates immune cells, and ERAP2N-expressing TCs are preferentially killed by both cytotoxic T lymphocytes (CTLs) and Natural Killer cells (NKCs). To understand the cause of this phenomenon, we surveyed differentially expressed genes (DEGs) between ERAP2N expressing and non-expressing TCs. Our RNAseq data revealed 581 total DEGs between the two groups. 289 genes were up-regulated, and 292 genes were down-regulated. Interestingly, most of the down-regulated genes of significance were pro-survival genes that play a crucial role in cell survival (LDHA, EGLN1, HLA-C, ITGB5, WNT7A, FN1). However, the down-regulation of these genes in ERAP2N-expressing TCs translates into a propensity for cell death. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that 64 DEGs were significantly enriched in nine pathways, including “Protein processing in endoplasmic reticulum” and “Antigen processing and presentation”, suggesting that the genes may be associated with peptide processes involved in immune recognition during the reproductive cycle.

Virus Infection and Death Receptor-Mediated Apoptosis

Virus infection can trigger extrinsic apoptosis. Cell-surface death receptors of the tumor necrosis factor family mediate this process. They either assist persistent viral infection or elicit the elimination of infected cells by the host. Death receptor-mediated apoptosis plays an important role in viral pathogenesis and the host antiviral response. Many viruses have acquired the capability to subvert death receptor-mediated apoptosis and evade the host immune response, mainly by virally encoded gene products that suppress death receptor-mediated apoptosis. In this review, we summarize the current information on virus infection and death receptor-mediated apoptosis, particularly focusing on the viral proteins that modulate death receptor-mediated apoptosis.

Clinical Role of Human Leukocyte Antigen in Health and Disease

Most of the genes in the major histocompatibility complex (MHC) region express high polymorphism that is fundamental for their function. The most important function of human leukocyte antigen (HLA) molecule is in the induction, regulation of immune responses and the selection of the T cell repertoire. A clinician's attention is normally drawn to a system only when it malfunctions. The HLA system is no exception in this regard, but in contrast to other systems, it also arouses interest when it functions well - too well, in fact. Population studies carried out over the last several decades have identified a long list of human diseases that are significantly more common among individuals that carry particular HLA alleles including inflammatory, autoimmune and malignant disorders. HLA-disease association is the name of this phenomenon, and the mechanism underlying is still a subject of hot debate. Social behaviours are affected by HLA genes and preference for HLA disparate mates may provide 'good genes' for an individual's offspring. Also, certain HLA genes may be associated with shorter life and others with longer lifespan, but the effects depend both on the genetic background and on the environmental conditions. The following is a general overview of the important functional aspects of HLA in health and diseases.

Role of non-classical MHC class I molecules in cancer immunosuppression

Growing neoplasms employ various mechanisms to evade immunosurveillance. The expression of non-classical MHC class I molecules by both immune and malignant cells in the tumor microenvironment constitute of the strategies used by tumors to circumvent the cytotoxic activity of effector cells of the immune system. The overexpression of HLA-G, -E, and -F is a common finding across a variety of malignancies. However, while the presence of HLA-G and HLA-E has been recently correlated with poor clinical outcome, information on the clinicopathological significance of HLA-F is limited. In the present review, we summarize studies on non-classical MHC class I molecules with special emphasis on their role in the modulation of anticancer immune responses.

MHC class I antigen processing and presenting machinery: organization, function, and defects in tumor cells

The surface presentation of peptides by major histocompatibility complex (MHC) class I molecules is critical to all CD8(+) T-cell adaptive immune responses, including those against tumors. The generation of peptides and their loading on MHC class I molecules is a multistep process involving multiple molecular species that constitute the so-called antigen processing and presenting machinery (APM). The majority of class I peptides begin as proteasome degradation products of cytosolic proteins. Once transported into the endoplasmic reticulum by TAP (transporter associated with antigen processing), peptides are not bound randomly by class I molecules but are chosen by length and sequence, with peptidases editing the raw peptide pool. Aberrations in APM genes and proteins have frequently been observed in human tumors and found to correlate with relevant clinical variables, including tumor grade, tumor stage, disease recurrence, and survival. These findings support the idea that APM defects are immune escape mechanisms that disrupt the tumor cells' ability to be recognized and killed by tumor antigen-specific cytotoxic CD8(+) T cells. Detailed knowledge of APM is crucial for the optimization of T cell-based immunotherapy protocols.

Systemic inhibition of myeloid dendritic cells by circulating HLA class I molecules in HIV-1 infection

BACKGROUND

HIV-1 infection is associated with profound dysfunction of myeloid dendritic cells, for reasons that remain ill-defined. Soluble HLA class I molecules can have important inhibitory effects on T cells and NK cells, but may also contribute to reduced functional properties of professional antigen-presenting cells. Here, we investigated the expression of soluble HLA class I isoforms during HIV-1 infection and assessed their functional impact on antigen-presenting characteristics of dendritic cells.

RESULTS

Soluble HLA class I molecules were highly upregulated in progressive HIV-1 infection as determined by quantitative Western blots. This was associated with strong increases of intracellular expression of HLA class I isoforms in dendritic cells and monocytes. Using mixed lymphocyte reactions, we found that soluble HLA class I molecules effectively inhibited the antigen-presenting properties of dendritic cells, however, there was no significant influence of HLA class I molecules on the cytokine-secretion properties of these cells. The immunomodulatory effects of soluble HLA class I molecules were mediated by interactions with inhibitory myelomonocytic MHC class I receptors from the Leukocyte Immunoglobulin Like Receptor (LILR) family.

CONCLUSIONS

During progressive HIV-1 infection, soluble HLA class I molecules can contribute to systemic immune dysfunction by inhibiting the antigen-presenting properties of myeloid dendritic cells through interactions with inhibitory myelomonocytic HLA class I receptors.

Soluble MHC I and soluble MIC molecules: potential therapeutic targets for cancer

It has become clear that soluble MHC I (sMHC I) and soluble MIC (sMIC), which are highly elevated in sera of cancer patients, can be viewed to be tolerogenic, and that metalloproteinases are involved in their generation process. In this review, an overview is provided of the recent progress made in the sMHC I and sMIC fields, with emphasis on their structure, formation, and function, and the key-questions that still await answers are addressed. Understanding better their formation mechanism, it will become more feasible to modulate the immune responses in cancer patients by targeting molecules involved in their generation process.

Soluble total human leukocyte antigen class I and human leukocyte antigen-G molecules in kidney and kidney/pancreas transplantation

The expression of human leukocyte antigen (HLA)-G, a nonclassical HLA class I molecule, and its soluble forms (sHLA-G) are found to improve graft acceptance. In this study we investigated whether sHLA-G is the most biologically relevant molecule among all types of soluble HLA class I molecules for graft acceptance. We addressed this question in kidney-transplanted (n = 32) and kidney/pancreas-transplanted patients (n = 29). To this end we analyzed the levels of total soluble HLA class I (sHLA-I) in comparison to sHLA-G in 488 plasma samples procured before and serial after transplantation by specific enzyme-linked immunoabsorbent assay. Samples from 126 healthy individuals served as controls. Pretransplantation sHLA-I levels were significantly increased in patients (p < 0.001), whereas sHLA-G levels were in the range of those of healthy controls. Importantly, pretransplantation sHLA-I and sHLA-G levels did not differ between the two groups. Patients with biopsy-proven rejection (n = 15) revealed significantly lower sHLA-G levels before transplantation (mean +/- standard error of the mean, 12.9 +/- 1.8 vs. 20.1 +/- 1.9, p = 0.013) and after transplantation (p = 0.006, two-way analysis of variance) than patients without rejection (n = 46). In contrast, sHLA-I was slightly increased after but not before transplantation in patients with rejection (p < 0.05, two-way analysis of variance). Nonparametric determination analysis showed that pretransplantation levels of sHLA-G < 11.5 ng/ml (sensitivity, 60%; specificity, 80.4%) were related to rejection. Regarding antibody status, retransplantation, number of HLA mismatches, recipient age, and recipient body mass index, multivariate analysis showed that sHLA-G but not sHLA-I is an independent risk factor for graft rejection. Thus high levels of sHLA-G but not of sHLA-I seem to contribute to better graft acceptance after kidney or kidney/pancreas transplantation.

Tumor escape mechanisms: potential role of soluble HLA antigens and NK cells activating ligands

The crucial role played by human leukocyte antigen (HLA) antigens and natural killer (NK)-cell-activating ligands in the interactions of malignant cells with components of the host's immune system has stimulated interest in the characterization of their expression by malignant cells. Convincing evidence generated by the immunohistochemical staining of surgically removed malignant lesions with monoclonal antibodies recognizing HLA antigens and NK-cell-activating ligands indicates that the surface expression of these molecules is frequently altered on malignant cells. These changes appear to have clinical significance because in some types of malignant disease they are associated with the histopathological characteristics of the lesions as well as with disease-free interval and survival. These associations have been suggested to reflect the effect of HLA antigen and NK-cell-activating ligand abnormalities on the interactions of tumor cells with antigen-specific cytotoxic T lymphocytes (CTL) and with NK cells. Nevertheless, there are examples in which disease progresses in the face of appropriate HLA antigen and/or NK-cell-activating ligand as well as tumor antigen expression by malignant cells and of functional antigen-specific CTL in the investigated patient. In such scenarios, it is likely that the tumor microenvironment is unfavorable for CTL and NK cell activity and contributes to tumor immune escape. Many distinct escape mechanisms have been shown to protect malignant cells from immune recognition and destruction in the tumor microenvironment. In this article, following the description of the structural and functional characteristics of soluble HLA antigens and NK-cell-activating ligands, we will review changes in their serum level in malignant disease and discuss their potential role in the escape mechanisms used by tumor cells to avoid recognition and destruction.

Clinical relevance of soluble HLA class I molecules in Waldenstrom Macroglobulinemia

OBJECTIVES

Waldenstrom Macroglobulinemia (WM) is a B-cell neoplasm characterised by secretion of IgM by lymphoplasmacytic bone marrow cells and by cytopenias and hypogammaglobulinemia in a subset of patients. Beta-2 microglobulin (b2m) is a major prognostic factor in WM and the heavy chain of HLA class I molecules, which are known to have immunosuppressive properties and have been implicated in the pathogeny of several malignancies.

METHODS

We assessed the serum levels of the total soluble HLA-I molecules and the HLA-Gs molecules in 105 patients with IgM-related disorders [WM (n = 42) and IgM MGUS (n = 63)], and compared the results to 41 healthy subjects.

RESULTS

We found higher levels of HLA-Is in WM, compared to IgM MGUS and healthy donors. HLA-Gs levels were similar in WM and in IgM MGUS, but higher than in healthy donors. The association between HLA-Is at the cut-off of 1.8 microg/mL and known markers of poor prognosis was then evaluated among WM patients using univariate and multivariate methods. Based on this, high HLA-Is level was strongly associated with high serum beta2M level >3 mg/L [OR = 2, (CI 95% 1.1-5.7); P = 0.04], age > 65 yrs [OR = 1.5, (CI 95% 0.5-4.1), P = 0.06] and haemoglobin < or =11.5 g/dL [OR = 3.3, (CI 95% 1.2-9.7); P = 0.03]. High levels of serum HLA-Is were also found in patients with cryoglobulinemia, however irrespectively of WM or IgM-MGUS status.

CONCLUSION

Together our results suggest a possible role for soluble MHC class I molecules in WM disease. Further investigations are necessary to further demonstrate the prognostic impact of soluble MHC class I molecules in Waldenstrom Macroglobulinemia.

Soluble HLA-G molecules increase during acute leukemia, especially in subtypes affecting monocytic and lymphoid lineages

Human leukocyte antigen G (HLA-G) molecules exhibit immunomodulatory properties corresponding to nonclassic class I genes of the major histocompatibility complex. They are either membrane-bound or solubly expressed during certain tumoral malignancies. Soluble human leukocyte antigen G (sHLA-G) molecules seem more frequently expressed than membrane-bound isoforms during hematologic malignancies, such as lymphoproliferative disorders. Assay of these molecules by enzyme-linked immunosorbent assay in patients suffering from another hematologic disorder (acute leukemia) highlights increased sHLA-G secretion. This increased secretion seems more marked in acute leukemia subtypes affecting monocytic and lymphoid lineages such as FABM4 and FABM5, as well as both B and T acute lymphoblastic leukemia (ALL). Moreover, this study uses in vitro cytokine stimulations and reveals the respective potential roles of granulocyte-macrophage colony-stimulating factor and interferon-gamma in increasing this secretion in FABM4 and ALL. Correlations between sHLA-G plasma level and clinical biologic features suggest a link between elevated sHLA-G level and 1) the absence of anterior myelodysplasia and 2) high-level leukocytosis. All these findings suggest that sHLA-G molecules could be a factor in tumoral escape from immune survey during acute leukemia.

Apoptosis of antigen-specific T lymphocytes upon the engagement of CD8 by soluble HLA class I molecules is Fas ligand/Fas mediated: evidence for the involvement of p56lck, calcium calmodulin kinase II, and Calcium-independent protein kinase C signaling pathways and for NF-kappaB and NF-AT nuclear translocation

The binding of soluble HLA class I (sHLA-I) molecules to CD8 on EBV-specific CTL induced up-regulation of Fas ligand (FasL) mRNA and consequent sFasL protein secretion. This, in turn, triggered CTL apoptosis by FasL/Fas interaction. Molecular analysis of the biochemical pathways responsible for FasL up-regulation showed that sHLA-I/CD8 interaction firstly induced the recruitment of src-like p56(lck) and syk-like Zap-70 protein tyrosine kinases (PTK). Interestingly, p59(fyn) was activated upon the engagement of CD3/TCR complex but not upon the interaction of sHLA-I with CD8. In addition, sHLA-I/CD8 interaction, which is different from signaling through the CD3/TCR complex, did not induce nuclear translocation of AP-1 protein complex. These findings suggest that CD8- and CD3/TCR-mediated activating stimuli can recruit different PTK and transcription factors. Indeed, the engagement of CD8 by sHLA-I led to the activation of Ca2+ calmodulin kinase II pathway, which eventually was responsible for the NF-AT nuclear translocation. In addition, we found that the ligation of sHLA-I to CD8 recruited protein kinase C, leading to NF-kappaB activation. Both NF-AT and NF-kappaB were responsible for the induction of FasL mRNA and consequent CTL apoptosis. Moreover, FasL up-regulation and CTL apoptotic death were down-regulated by pharmacological specific inhibitors of Ca2+/calmodulin/calcineurin and Ca2+-independent protein kinase C signaling pathways. These findings clarify the intracellular signaling pathways triggering FasL up-regulation and apoptosis in CTL upon sHLA-I/CD8 ligation and suggest that sHLA-I molecules can be proposed as therapeutic tools to modulate immune responses.

Total Soluble HLA Class I and Soluble HLA-G in Multiple Myeloma and Monoclonal Gammopathy of Undetermined Significance

Serum beta2-microglobulin, the light chain of the HLA class I molecular complex, remains one of the best survival prognostic factors in multiple myeloma, but other HLA class I molecules might be of interest in monoclonal gammopathies. In this study, we evaluate total soluble HLA class I (HLA-Is) and soluble HLA-G (HLA-Gs) in 103 patients with newly diagnosed multiple myeloma, 30 patients with monoclonal gammopathy of undetermined significance (MGUS), and 30 healthy subjects, studying their prognostic value in multiple myeloma. In multiple myeloma patients, HLA-Is and HLA-Gs median values were 0.8 microg/mL and 28 ng/mL, respectively. Median HLA-Is concentration was higher in stage II and III multiple myeloma patients than in stage I multiple myeloma, MGUS, and control patients. Median HLA-Gs was significantly lower in healthy controls than in MGUS and multiple myeloma patients. A high level of HLA-Is (> or =2.1 microg/mL) was predictive of short survival (P = 0.017). For each given level of beta2-microglobulin, the relative risk of death was higher for patients with HLA-Is > or = 2.1 microg/mL than in patients with a lower level (P = 0.047). HLA-Gs, a marker of monoclonal gammopathy, was of no prognostic value, but the addition of HLA-Is to beta2-microglobulin produced an efficient prognostic score (P < 0.0001). HLA-Is is a new marker of multiple myeloma tumor load and provides additional survival prognostic information to beta2-microglobulin.

Soluble HLA-G molecules are increased in lymphoproliferative disorders

The immunomodulatory properties of soluble human leukocyte antigen G (sHLA-G) explain its potential interest in malignancies. HLA-G frequently transcribed in lymphoproliferative disorders is rarely expressed at cell surface. In this article, we will demonstrate that the plasmatic level of soluble HLA-G was significantly increased in 70% of B chronic lymphocytic leukemia, 53% of non-Hodgkin B lymphoma (B-NHL), and 45% of T-NHL. To explain this variable secretion, the HLA-G secreting cell was searched and was identified as tumoral T4 lymphocytes only in one patient with Sezary syndrome. To approach the mechanisms involved in sHLA-G secretion, the potential role of cytokines has been studied in vitro on T lymphomas. A significant increase of sHLA-G level is observed after activation by cytokines associated with a small increase in the quantity of transcripts using real-time polymerase chain reaction, suggesting an involvement of both transcriptional and post-transcriptional mechanisms. Western Blot analysis reveals no evident variation of the protein expression whatever the conditions, suggesting a continuous secretion and a low intracellular storage. The frequency of the sHLA-G secretion associated to its inhibiting role on T cells and natural killer cells during tumoral lymphoid malignancies suggests a potential role of these molecules as escape mechanism from antitumoral response.

Role of NK and NKT cells in the immunopathogenesis of HCV-induced hepatitis

Natural killer (NK) cells constitute the first line of host defense against invading pathogens. They usually become activated in an early phase of a viral infection. Liver is particularly enriched in NK cells, which are activated by hepatotropic viruses such as hepatitis C virus (HCV). The activated NK cells play an essential role in recruiting virus-specific T cells and in inducing antiviral immunity in liver. They also eliminate virus-infected hepatocytes directly by cytolytic mechanisms and indirectly by secreting cytokines, which induce an antiviral state in host cells. Therefore, optimally activated NK cells are important in limiting viral replication in this organ. This notion is supported by the observations that interferon treatment is effective in HCV-infected persons in whom it increases NK cell activity. Not surprisingly, HCV has evolved multiple strategies to counter host's NK cell response. Compromised NK cell functions have been reported in chronic HCV-infected individuals. It is ironic that activated NK cells may also contribute toward liver injury. Further studies are needed to understand the role of these cells in host defense and in liver pathology in HCV infections. Recent advances in understanding NK cell biology have opened new avenues for boosting innate and adaptive antiviral immune responses in HCV-infected individuals.

HLA-G and lymphoproliferative disorders

The immunomodulatory properties of the HLA-G molecule explain its relevance in malignancies. Our investigations in lymphoproliferative disorders show (i) a frequent and variable distribution of alternatively spliced HLA-G mRNA isoforms, (ii) a rare cell surface expression in diffuse large cell lymphomas with HLA class I loss in half of cases, and (iii) an increased serum level of sHLA-G in half of cases. The potential role of the microenvironment and/or tumoral process in HLA-G expression is discussed in the light of these data. HLA-G rather through its soluble isoform might provide a new way of immune evasion for lymphoid proliferations.

HLA-G modulates immune responses by diverse receptor interactions

HLA-G regulates immune responses as it binds different receptors expressed on natural killer (NK) cells, T cells and myeloid cells. HLA-G1 can inhibit NK- and T-cell-mediated lysis of target cells by its interaction with the inhibitory receptors ILT2 and ILT4. Engaging KIR2DL4 triggers different reactions depending on the activation state of the effector cells. The indirect recognition of HLA-G as peptide presented by HLA-E and recognized by the CD94/NKG2 receptor family might further power the battle between the immune system and tumor cells. Secreted HLA-G5 can also bind CD8 and induces Fas/Fas ligand-mediated apoptosis in activated CD8+ lymphocytes.

In vitro immunosuppressive activity of soluble HLA class I and Fas ligand molecules: do they play a role in autologous blood transfusion?

BACKGROUND

The immunomodulatory effects of allogeneic blood transfusion may contribute to a poor prognosis in patients with cancer who are undergoing surgery, and clinical trials have been carried out to investigate whether these patients would benefit from autologous blood donation. As the immunomodulatory effects of allogeneic blood transfusion have been related to soluble molecules released from residual WBCs during storage, the in vitro immunomodulatory activity of soluble molecules detected in supernatants from stored autologous blood was evaluated.

STUDY DESIGN AND METHODS

Blood was donated by four healthy volunteers. Packed WBC-reduced RBCs were obtained and stored for 30 days, and supernatants were collected. FFP and serum were also obtained. The concentration of soluble molecules was determined by immunoenzymatic assays. The in vitro immunomodulatory activity of undiluted blood component supernatant was assessed by antigen-specific cytotoxic T-cell activity and mixed lymphocyte reactions in autologous combinations and by apoptosis induction in Fas+ cells.

RESULTS

The concentrations of soluble Fas-ligand and HLA class I molecules were higher in packed RBCs than in WBC-reduced RBCs, FFP, and serum. Undiluted supernatants of packed RBCs strongly inhibited functional assays and induced apoptosis in Fas+ cells. The immunomodulatory effects were correlated with the amount of soluble Fas ligand and HLA class I molecules.

CONCLUSION

The results of the present study are comparable with those already reported in allogeneic blood components, and they indicate that undiluted supernatants of autologous blood components may exert immunosuppressive effects in vitro.