Soluble B7-H4 Research Articles

SB7-H4 is a diagnostic biomarker in epithelial ovarian cancer and correlates to platinum resistance.

Ovarian cancer, with its high mortality rate among gynecological cancers, is often diagnosed late due to the lack of early diagnostic symptoms and biomarkers. The tumor immune microenvironment has become a focal point in cancer diagnostic and therapeutic research. Among these, B7-H4, a checkpoint protein, plays a crucial role in immune regulation and tumor suppression, contributing to immune evasion within the tumor microenvironment. This study aims to identify the concentration of soluble B7-H4(sB7-H4) in the plasma of patients with ovarian cancer and to evaluate its clinical significance. Through a comprehensive analysis involving enzyme-linked immunosorbent assay, immunohistochemistry, and multicolor immunofluorescence, we quantified sB7-H4 levels in patient plasma and ascites, correlating these findings with tissue expression and clinical outcomes. Results indicated a strong association between high sB7-H4 levels and advanced disease, surgical outcomes, lymphatic metastasis, and platinum resistance. When compared with traditional biomarkers CA125 and HE4, sB7-H4, especially in conjunction with these markers, enhances the diagnostic accuracy for epithelial ovarian cancer, offering insights into disease progression and therapeutic efficacy. This comprehensive analysis suggests that sB7-H4 is a promising biomarker for EOC, providing valuable insights into diagnosis, stage differentiation, treatment effectiveness, and prognosis.

Impact of the Immunomodulatory Factor Soluble B7-H4 in the Progress of Preeclampsia by Inhibiting Essential Functions of Extravillous Trophoblast Cells.

A key aspect of preeclampsia pathophysiology is the reduced invasiveness of trophoblasts and the impairment of spiral artery remodelling. Understanding the causes of altered trophoblast function is critical to understand the development of preeclampsia. B7-H4, a checkpoint molecule, controls a wide range of processes, including T-cell activation, cytokine release, and tumour progression. Our previous findings indicated that B7-H4 levels are elevated in both maternal blood and placental villous tissue during the early stages of preeclampsia. Here, we investigated the function of B7-H4 in trophoblast physiology. Recombinant B7-H4 protein was used to treat human SGHPL-5 extravillous trophoblast cells. Biological functions were investigated using MTT, wound healing, and transwell assays. Signalling pathways were analysed by immunoblotting and immunofluorescence. The functionality of B7-H4 was further confirmed by immunoblotting and immunohistochemical analysis in placental tissues from control and preeclamptic patients following therapeutic plasma exchange (TPE) or standard of care treatment. This study showed that B7-H4 inhibited the proliferation, migration, and invasion capacities of SGHPL-5 extravillous cells while promoting apoptosis by downregulating the PI3K/Akt/STAT3 signalling pathway. These results were consistently confirmed in placental tissues from preterm controls compared to early-onset preeclamptic placental tissues from patients treated with standard of care or TPE treatment. B7-H4 may play a role in the development of preeclampsia by inhibiting essential functions of extravillous trophoblast cells during placental development. One possible mechanism by which TPE improves pregnancy outcomes in preeclampsia is through the elimination of B7-H4 amongst other factors.

Association of B7H3 and B7H4 gene polymorphisms and protein expression with the development and prognosis of autoimmune thyroid diseases.

The prognosis of autoimmune thyroid diseases (AITDs), including Graves' disease (GD) and Hashimoto's disease (HD), varies among patients. B7-H3 and B7-H4, members of the B7 family of proteins, regulate immune response. To clarify the association of B7-H3 and B7-H4 with the pathogenesis and prognosis of AITDs, we examined the expression of the soluble and membrane form of B7-H3 and B7-H4 and genotyped single nucleotide polymorphisms (SNPs) in the B7H3 and B7H4 genes. We examined the expression of the membrane form of B7-H3 and B7-H4 by flow cytometry and their soluble forms by enzyme-linked immunosorbent assay. We genotyped SNPs in B7H3 and B7H4 in 187 GD patients, 217 HD patients, and 110 healthy volunteers using the PCR-RFLP method. The frequency of the B7H3 rs3816661 CC genotype was higher in patients with severe HD. G carriers of B7H4 rs10754339 A/G and B7H4 rs13505 T/G were more frequent in patients with AITD. A carrier of B7H4 rs10158166 A/G and C carriers of B7H4 rs3806373 C/T were more frequent in patients with intractable GD. The proportion of B7-H3+ monocytes was higher in the CC genotype of B7H3 rs3816661 C/T than in the other genotypes and was lower in patients with GD and HD than in healthy controls. The concentration of soluble B7-H4 was lower in the TG genotype of B7H4 rs13505 T/G than in the TT genotype and was higher in patients with AITD than in healthy controls. B7H3 and B7H4 are associated with AITD susceptibility and prognosis.

The immunological role of B7-H4 in pregnant women with Sars-Cov2 infection.

ProblemT‐cells are key players in fighting the coronavirus disease 2019 (COVID‐19). The checkpoint molecule B7‐H4, a member of the B7 family, can inhibit T‐cell activation and proliferation by inhibiting NF‐kb expression. We aimed to elucidate the immunological role of soluble B7‐H4 (sB7‐H4) and B7‐H4 in pregnant women suffered from an acute Sars‐Cov2 infection.MethodsExpression levels of sB7‐H4 and cytokines were detected by enzyme linked immunosorbent assay. B7‐H4 and cytokines mRNA expression was analyzed by qPCR, and B7‐H4 and NF‐κb (p65) protein levels were investigated by western blot and immunofluorescence staining in placenta chorionic villous and decidual basalis tissues of COVID‐19 affected women and healthy controls.ResultsFibrinoid necrosis in the periphery of placental villi was increased in the COVID‐19‐affected patients. sB7‐H4 protein in maternal and cord blood serum and IL‐6/IL‐10 were increased while leukocytes were decreased during SARS‐CoV‐2 infection. Serum sB7‐H4 level was increased according to the severity of SARS‐Cov‐2 infection. Cytokines (IL‐6, IL‐18, IL‐1β, TNF‐α), B7‐H4 mRNA and protein in the decidual basalis tissues of COVID‐19‐infected pregnant women were significantly increased compared to healthy controls. IL‐18 and IL‐1β were significantly increased in the placenta chorionic villous samples of COVID‐19 affected patients, while NF‐κb (p65) expression was decreased.ConclusionsThe expression of the immunological marker sB7‐H4 correlated with the severity of COVID‐19 disease in pregnant women. sB7‐H4 and B7‐H4 can be used to monitor the progression of COVID‐19 infection during pregnancy, and for evaluating of the maternal immune status.

Upregulation of B7-H4 Is Involved in and Related to the Severity of Acute Pancreatitis.

The expression and clinical significance of co-stimulator B7-H4 in acute pancreatitis (AP) is still unclear. In vitro study showed that the expression of soluble B7-H4 (sB7-H4) and proportions of membrane B7-H4-positive CD14+ cells in the peripheral blood mononuclear cells were upregulated in response to stimulation with plasma from AP patients, lipopolysaccharides, or tumor necrosis factor α (TNF-α). sB7-H4 in the plasma of AP patients were positively correlated with interleukin (IL)-6, IL-10, IL-17A, TNF-α, and interferon-γ The areas under the curves (AUCs) of receiver operating characteristic (ROC) curves of plasma sB7-H4 to distinguish the AP patients from healthy donors, the mild AP (MAP) from the moderately severe acute pancreatitis (MSAP)+severe acute pancreatitis (SAP) or the SAP from the MAP+MSAP were 0.78 (P < 0.001) or 0.773 (P < 0.001) or 0.764 (P < 0.001). sB7-H4 in the plasma of patients were positively correlated with the RANSON scores, Bedside Index of Severity of Acute Pancreatitis scores, Marshall scores, and Acute Physiology And Chronic Health Evaluation II scores; and the AUCs of ROC curves of plasma sB7-H4 in the prediction of local complications was 0.726 (P = 0.001). In conclusion, the co-stimulator B7-H4 is involved in the immune response in AP.

Association of Soluble B7-H4 and Circulating Tumor Cells in Blood of Advanced Epithelial Ovarian Cancer Patients.

IntroductionEpithelial ovarian cancer (EOC) is the deadliest gynecologic malignancy worldwide. Reliable predictive biomarkers are urgently needed to estimate the risk of relapse and to improve treatment management. Soluble immune-checkpoints in EOC are promising molecules serving as prognostic biomarkers accessible via liquid biopsy. We thus, aimed at elucidating the role of sB7-H4 in EOC.Material and MethodsWe analyzed soluble serum B7-H4 (sB7-H4) using ELISA and circulating tumor cells (CTCs) in blood applying the AdnaTest OvarianCancer in 85 patients suffering from advanced EOC. Findings were correlated with clinical parameters as well as survival data.ResultssB7-H4 was detectable in 14.1% patients, CTCs in 32.9% patients and simultaneous presence of CTCs and sB7-H4 was found in 7% patients, respectively. Although no association between sB7-H4 and CTC could be documented, each of them served as independent predictive factors for overall survival (OS).ConclusionsB7-H4 and CTCs are independent prognostic biomarkers for impaired survival in EOC. As they are easily accessible via liquid biopsy, they may be of potential benefit for the prediction of therapy response and survival for EOC patients.

Establishment of a novel double-monoclonal antibody sandwich enzyme-linked immunosorbent assay (ELISA): tool for human B7-H4 detection in autoimmune diseases.

B7-H4, one of the immunoregulatory proteins, plays an inhibitory role by inhibiting T cell proliferation and cytokine production. Nevertheless, the significance of soluble B7-H4 (sB7-H4) in autoimmune diseases is unclear. In our study, we developed two novel mouse anti-human B7-H4 monoclonal antibodies (mAbs) (clones 8D4 and 7E1) with utilities for flow cytometry, immunoblotting and immunofluorescence. We characterized 7E1 as a functional antibody with antagonistic activity, which could promote T cell proliferation and regulate cytokine production. Furthermore, based on the different epitope specificities, we established a novel enzyme-linked immunosorbent assay (ELISA) which could detect sB7-H4 sensitively and specifically. Using this ELISA kit, sB7-H4 was observed in a high proportion of autoimmune diseases patients. We found that the levels of sB7-H4 were significantly higher in patients with systemic lupus erythematosus (SLE), type I diabetes (T1D) and Graves' disease (GD). Together, sB7-H4 in human serum is regarded not only as a regulator of T cell activation but may also be a diagnostic marker of autoimmune diseases.

Abnormal expression of the costimulatory molecule B7-H4 in placental chorionic villous and decidual basalis tissues of patients with preeclampsia and HELLP syndrome.

B7-H4, a checkpoint molecule of the B7 family, regulates a broad spectrum such as T-cell activation, cytokine secretion, tumour progression, and invasion capacities. Our previous data revealed that soluble B7-H4 (sB7-H4) blood serum levels are elevated in women at high risk for the hypertensive pregnancy disorder preeclampsia (PE) in the first trimester, as well as in patients with confirmed early/late-onset PE. We here aim to investigate the expression pattern of B7-H4 in placental tissues of PE and HELLP Syndrome versus control group. B7-H4 protein expression and localization were investigated by immunoblotting and co-immunohistochemistry in placental chorionic villous and decidual basalis tissues. B7-H4 protein was prominently expressed at the cell membrane, in the cytoplasm of the syncytiotrophoblast (STB) and interstitial extravillous trophoblast (EVT). B7-H4 protein levels in placental chorionic villous tissue were significantly higher in women with early-onset/late-onset PE and HELLP, while it was decreased in decidual basalis tissues of early-onset PE and HELLP compared with controls. B7-H4 was inversely expressed in placental chorionic villous and decidual basalis tissues of PE and HELLP patients. The increase in B7-H4 in the STB in PE and HELLP may lead to excessive apical expression and release of soluble B7-H4 in the maternal circulation. In contrast, the decrease in B7-H4 in decidual basalis tissues could be related to the decrease in invasion ability of the EVT in PE. Thus, the current results strongly suggest that B7-H4 is involved in the pathogenesis of PE and HELLP.

Predictive value of serum soluble B7-H4 in acute pancreatitis.

Studies reported that soluble B7-H4 (sB7-H4) was significantly related to the progression and prognosis of inflammatory diseases, and whether sB7-H4 is related to the severity and prognosis of acute pancreatitis (AP) timely has not been reported. Clinical database data of 446 AP patients were retrospectively collected, and the correlation between the expression serum levels of sB7-H4 with inflammatory factors and prognostic scores was analysed in AP patients. Soluble B7-H4 was significantly correlated with IL-6, IL-8, TNF-α, PCT, CRP levels and WBC count (P<.01), with correlation coefficients of R=.61, .53, .46, .60, .57 and .47, respectively, and AUCs were 0.905, 0.837, 0.797, 0.858, 0.890, 0.841 and 0.855, respectively. In addition, sB7-H4 was significantly correlated with the Ranson score, APACHE II score and BISAP score (P<.001), with correlation coefficients of R=.58, .63 and .59, respectively. The AUCs of assessing local complications of AP were 0.908, 0.863, 0.785 and 0.844, respectively; assessing organ failure were 0.872, 0.790, 0.796 and 0.857, respectively; and assessing in-hospital mortality were 0.839, 0.821, 0.796 and 0.823, respectively. Soluble B7-H4 could be used as a marker for the diagnosis, severity assessment and poor prognosis assessment of AP patients, which may have potential clinical applications.

Increased Serum Levels of Soluble B7-H4 in Patients with Systemic Lupus Erythematosus.

Members of B7 family are reported to regulate lymphocytes activation, transmit both costimulatory and co-inhibitory signals, control T cell-mediated immune responses and tolerance. Among which B7-H4 is reported to regulate the immune response negatively. To investigate the plasma concentration of soluble B7-H4 (sB7-H4) and its clinical significance in systemic lupus erythematosus (SLE). Fifty-six SLE patients with or without active SLE (ASLE) and 29 age- and gender-matched healthy volunteers were recruited. Plasma concentration of sB7-H4 was measured using sandwich ELISA kits. Compared with healthy subjects, the concentration of sB7-H4 was significantly higher in patients with SLE (p=0.006). Plasma sB7-H4 concentration in patients with lupus nephritis (LN) were also significantly higher than healthy subjects (p=0.008), but no difference was found between LN and SLE patients without LN (non-LN). Additionally, the sB7-H4 concentration in patients was negatively correlated with the SLE disease activity index score (SLEDAI) (r=-0.3055, p=0.022). Compared with inactive disease, the concentration of sB7-H4 in ASLE patients was significantly lower (p=0.002). There were statistical significances between the positive and negative groups with decreased leukocytes or thrombocytes (p=0.012; p=0.033; respectively), but no statistically significant difference was found in other positive and negative serum laboratory indicators. The increased level of sB7-H4 in patients suggests that this pathway might be involved in the pathogenesis of SLE. However, the exact mechanism or physiological role of sB7-H4 in SLE pathogenesis remains to be investigated.

Expression of sB7-H4 in Serum and Lymphoma Tissues of Patients with Malignant Lymphoma and Its Value for Diagnosis and Re-Examine of Lymphoma

To study the soluble B7-H4 (sB7-H4) expression in serum and lymphoma tissues of patients with malignant lymphoma (ML) and its value for diagnosis and re-examination lymphoma. The serum samples from 83 cases of ML were collected, among them 69 cases of newly diagnosed ML were enrolled in group A including 11 cases of Hodgkin's lymphoma (NHL group) and 58 cases of non-Hodgkin's lymphoma (NHL group), the serum samples from 14 cases of relapsed ML were enrolled in group B; at the same time the serum samples of 50 healthy persons conformed by physical examination were collected and enrolled in control group. The double antibody sandwich ELISA was used to detect the serum level of sB7-H4 in each group, and immunohistochemistry method was used to detect the expression of sB7-H4 in malignant lymphoma and reactive lymphoid hyperplasia tissues. The serum level of sB7-H4 in the group A was significantly increased in comparison with the group B and control group, and the level of group B was significantly higher than that in the control group (P<0.05); the serum level of sB7-H4 in the NHL group was significantly increased in comparison with HL group and control group, and the level of HL group was higher than that of control group (P<0.05). The expression of sB7-H4 in reactive lymphoid hyperplasia tissues was negative, but the positive expression rate in malignant lymphoma tissues was 47.50%, suggesting the positive rate of sB7-H4 in malignant lymphoma tissues was significantly higher than that of reactive lymphoid hyperplasia tissues (P<0.05). The high expression of sB7-H4 in serum and lymphoma tissues of patients with malignant lymphoma has a certain value for the diagnosis and re-examination of patients with malignant lymphoma.

118. Significant increase of soluble B7-H4 in women at high-risk for preeclampsia in the first trimester: A potential immunological biomarker for immunologically-mediated pregnancy complications?

Introduction The successful outcome of pregnancy requires adequate immune tolerance. A lack of appropriate tolerance might cause placental dysfunction and pregnancy complications such as preeclampsia (PE). Members of the B7 family play an essential role in maintaining immune tolerance in pregnancy by effecting T cells. Objectives B7-H4 is responsible for the negative regulation of T-cell-mediated immune response and might play an important role in PE. We currently revealed that sB7-H4 is involved in the spontaneous onset of labor and is elevated in early pregnancy in women with a preterm premature rupture of the amniotic membranes (pPROM). Thus, here we investigated the association between PE and sB7-H4 levels. Material and methods Maternal serum levels of sB7-H4 were determined by enzyme-linked immunosorbent assay in first trimester with elevated risk for PE Results In women at elevated risk for PE in first trimester significantly higher levels of sB7-H4 were detected compared to controls (p Conclusion sB7-H4 is involved in the regulation of immune tolerance in women with PE in the third trimester. In the first trimester, sB7-H4 might serve as a predictive immunological biomarker for women who are at elevated risk of developing PE.

Correction: Serum soluble B7-H4 is a prognostic marker for patients with non-metastatic clear cell renal cell carcinoma.

[This corrects the article DOI: 10.1371/journal.pone.0199719.].

Serum soluble B7-H4 is a prognostic marker for patients with non-metastatic clear cell renal cell carcinoma.

BackgroundB7-H4 is a member of the B7 family of immune-regulatory ligands and is considered to be a negative regulator of the immune response. We investigated the clinical significance of serum soluble B7-H4 in patients with non-metastatic clear cell renal cell carcinoma.MethodsWe analyzed 108 patients in whom non-metastatic clear cell renal cancer was diagnosed at Tokyo Metropolitan Tama Medical Center between 2008 and 2013. We measured the serum soluble B7-H4 level using the Enzyme-Linked ImmunoSorbent Assay (ELISA) and evaluated the association between the peripheral blood neutrophil count and sB7-H4 as well as the utility of soluble B7-H4 as a prognostic biomarker for clear cell renal cancer. The Cox proportional hazards regression model was used to assess the PFS and OS with the soluble B7-H4 level.ResultsWe detected high levels of soluble B7-H4 in the sera of 56% of patients with non-metastatic clear cell renal cell carcinoma versus only 10% of healthy donors. Elevated soluble B7-H4 levels were associated with changes in an elevated peripheral blood neutrophil count. The increase of soluble B7-H4 also was significantly associated with poor PFS and OS. Multivariate analysis showed that the elevation of the soluble B7-H4 level was an independent prognostic factor for PFS and OS.ConclusionsOur data suggest that the association between serum soluble B7-H4 and peripheral blood neutrophil count, as well as the evaluation of serum soluble B7-H4 expression is a useful tool for predicting the prognosis of patients with non-metastatic clear cell renal cell carcinoma.

Soluble B7‐H4 blood serum levels are elevated in women at high risk for preeclampsia in the first trimester, as well as in patients with confirmed preeclampsia

B7-H4 negatively regulates T-cell-mediated immunity and might play an important role in preeclampsia (PE). Here, we have investigated the association between PE and maternal soluble B7-H4 (sB7-H4) serum levels and B7-H4 mRNA expression in the placenta. Maternal serum levels of sB7-H4 were determined by enzyme-linked immunosorbent assay in women between 11 and 13weeks' gestation with elevated risk for PE (n=48) and women without elevated risk for PE (n=47). In the third trimester, sB7-H4 serum levels (n=166) and B7-H4 mRNA expression in the placenta (n=54) were determined in women with early-onset PE, late-onset PE, fetal growth restriction (FGR), and in healthy controls. In the first trimester, significant higher levels of sB7-H4 were detected in women at elevated risk for PE compared to women without risk for PE (P<.0001). sB7-H4 has some predictive ability to identify cases with an elevated risk of developing PE with area under the curve (AUC) value of 0.88 (95% CI 0.8-0.94). Using a specificity of 90.0% led to a sensitivity of 47.9% and a threshold of 3.63ng/mL. In the third trimester, the highest serum levels of sB7-H4 and B7-H4 mRNA expression in the placenta were observed in early-onset PE. Significant higher serum levels of sB7-H4 and B7-H4 mRNA expression in the placenta were observed in women with early-onset PE (P=.01 and P=.006, respectively) and late-onset PE (P=.03 and P=.004, respectively) compared to healthy controls, but not compared to FGR. sB7-H4 is involved in the regulation of immune tolerance in women with PE in the third trimester. In the first trimester of pregnancy, sB7-H4 might serve as a predictive immunological biomarker for women who are at elevated risk of developing PE.

Diagnostic value of soluble B7-H4 and carcinoembryonic antigen in distinguishing malignant from benign pleural effusion.

To explore the diagnostic value of joint detection of soluble B7-H4 (sB7-H4) and carcinoembryonic antigen (CEA) in identifying malignant pleural effusion (MPE) from benign pleural effusion (BPE). A total of 97 patients with pleural effusion specimens were enrolled from The First Affiliated Hospital of Zhengzhou University between June 2014 and December 2015. All cases were categorized into malignant pleural effusion group (n=55) and benign pleural effusion group (n=42) according to etiologies. Enzyme-linked immunosorbent assay was applied to examine the levels of sB7-H4 in pleural effusion and meanwhile CEA concentrations were detected by electro-chemiluminescence immunoassays. Receiver operating characteristic (ROC) curve was established to assess the diagnostic value of sB7-H4 and CEA in pleural effusion. The correlation between sB7-H4 and CEA levels was analyzed by Pearson's product-moment. The concentrations of sB7-H4 and CEA in MPE exhibited obviously higher than those of BPE ([60.08±35.04] vs. [27.26±9.55]ng/ml, P=.000; [41.49±37.16] vs. [2.41±0.94]ng/ml, P=.000). The AUC area under ROC curve of sB7-H4 and CEA was 0.884 and 0.954, respectively. Two cutoff values by ROC curve analysis of sB7-H4 36.5ng/ml and CEA 4.18ng/ml were obtained, with a corresponding sensitivity (81.82%, 87.28%), specificity (90.48%, 95.24%), accuracy (85.57%, 90.72%), positive predictive value (PPV) (91.84%, 96.0%), negative predictive value (NPV) (79.17%, 85.11%), positive likelihood ratio (PLR) (8.614, 18.327), and negative likelihood ratio (NLR) (0.201, 0.134). When sB7-H4 and CEA were combined to detect pleural effusion, it obtained a higher sensitivity 90.91% and specificity 97.62%. Furthermore, correlation analysis result showed that the level of sB7-H4 was correlated with CEA level (r=.770, P=.000). sB7-H4 was a potentially valuable tumor marker in the differentiation between BPE and MPE. The combined detection of sB7-H4 and CEA could improve the diagnostic sensitivity and specificity for MPE.

Changes in the blood serum levels of the co-stimulatory soluble B7-H4 molecule in pregnant women during the peripartal phase

Aim of the study: B7-H4, a transmembrane protein that negatively regulates T lymphocytes, seems to play a role in the suppression of the immune response at the maternal-fetal interface. The aim of this study was to compare serum levels of soluble B7-H4 prepartal and postpartal in women with spontaneous onset of labor and elective cesarian section.

Serum concentrations of soluble B7-H4 in early pregnancy are elevated in women with preterm premature rupture of membranes

Serum concentrations of soluble B7-H4 in early pregnancy are elevated in women with preterm premature rupture of membranes

Prognostic values of B7-H4 in non-small cell lung cancer

Objective: The aim of this study was to explore the prognostic value of serum soluble B7-H4 (sB7-H4) levels in patients with non-small cell lung cancer (NSCLC).Methods: Serum specimens from 316 NSCLC patients and 240 healthy controls were collected. The concentrations of sB7-H4 were measured by ELISA.Results: The levels of sB7-H4 in NSCLC patients were significantly higher than that of the controls (P<0.01). Multivariate survival analysis indicated that sB7-H4 was an independent prognostic indicator of overall survival and progression-free survival (P<0.01).Conclusions: Measurement of serum sB7-H4 might be a useful prognostic biomarker for NSCLC.

Diagnosis value of serum soluble B7-H4 expression in non-small cell lung cancer.

B7-H4, a member of the inhibitory B7 family, can restrain T cell proliferation, activation, cytokine secretion, and may be involved in immune evasion in cancer patients. This aim of the study was to determine the expression level of soluble B7-H4 (sB7-H4) in circulation and to subsequently evaluate the clinical significance of circulating sB7-H4 in patients with non-small cell lung cancer (NSCLC). Serum specimens from 128 patients with NSCLC, 100 healthy volunteers (HV), and 80 patients with benign lung diseases (BLD) were collected. The concentrations of sB7-H4 were measured by sandwich enzyme-linked immunosorbent assay. Serum sB7-H4 levels in patients with NSCLC were significantly higher than those in patients with BLD (P < 0.05), or those in HV (P < 0.05). Using a cutoff of 27.8 ng/mL, the sensitivity and specificity of sB7-H4 in differentiating between patients with NSCLC and patients with BLD, and between patients with NSCLC and HV was, 46.9% and 92.5%, and 54.7% and 95.0%, respectively. An area under the curve (AUC) for NSCLC resulting from sB7-H4 (0.863), which was significantly better than any other tumour markers tested including CA125 (0.763), and CEA (0.775). In conclusion, assessment of serum sB7-H4 levels could be considered as a diagnostic biomarker for NSCLC.