Chronic active Epstein-Barr virus disease originates from infected hematopoietic stem cells.

ABSTRACT: Chronic active Epstein-Barr virus (EBV) disease (CAEBV) is a lethal syndrome because of persistent EBV infection. When diagnosed as CAEBV, EBV infection was observed in multiple hematopoietic lineages, but the etiology of CAEBV is still elusive. Bone marrow and peripheral cells derived from 5 patients with CAEBV, 1 patient with EBV-associated hemophagocytic lymphohistiocytosis, and 2 healthy controls were analyzed. Multiple assays were applied to identify and characterize EBV-infected cells, including quantitative polymerase chain reaction, PrimeFlow, and single-cell RNA-sequencing (scRNA-seq). Based on scRNA-seq data, alterations in gene expression of particular cell types were analyzed between patients with CAEBV and controls, and between infected and uninfected cells. One patient with CAEBV was treated with allogeneic hematopoietic stem cell transplantation (HSCT), and the samples derived from this patient were analyzed again 6 months after HSCT. EBV infected the full spectrum of the hematopoietic system including both lymphoid and myeloid lineages, as well as the hematopoietic stem cells (HSCs) of the patients with CAEBV. EBV-infected HSCs exhibited a higher differentiation rate toward downstream lineages, and the EBV infection had an impact on both the innate and adaptive immunity, resulting in inflammatory symptoms. EBV-infected cells were thoroughly removed from the hematopoietic system after HSCT. Taken together, multiple lines of evidence presented in this study suggest that CAEBV disease originates from the infected HSCs, which might potentially lead to innovative therapy strategies for CAEBV.

The effectiveness of the doxorubicin-etoposide-methylprednisolone regimen for adult HLH secondary to rheumatic disease.

To investigate the efficacy of the doxorubicin-etoposide-methylprednisolone, DEP) regimen as an effective treatment for adult Hemophagocytic Lymphohistiocytosis secondary to rheumatic disease and analyze prognosis in these patients. Fifty-eight adult patients diagnosed with Hemophagocytic Lymphohistiocytosis secondary to rheumatic disease admitted to Beijing Friendship Hospital from 1st Jan. 2018 to 31st Dec. 2022 were retrospectively included in this study. Patients were grouped according to previous treatment. Clinical data and laboratory characteristics of patients were retrospectively analyzed. The efficacy was evaluated every 2 weeks after initiating the first course of the DEP regimen and until the last inpatient or 31st Dec. 2023. 26 patients were included in Group A and 32 patients were included in Group B due to the previous treatment. After the first course of the DEP regimen, the overall response rate of all patients was 82.8%, with 13.8% in complete response and 69% in partial response. There was no significant statistical objective response rate between the two groups after the DEP regimen, except at 2-week. Serum ferritin, sCD25, ALT, AST, and DBIL concentrations were significantly lower at 2, 4 and 6-week than pre-treatment (P < 0.05). The overall mortality rate is 20.7% (12/58). Importantly, advanced age, initial level of HB and PLT, and central nervous system (CNS) involvement were independent poor risk factors affecting OS in bivariate analysis. The DEP regimen is effective for adult HLH secondary rheumatic disease with a high overall rate and accepted side effects.

Prognostic scoring system for pediatric Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis based on baseline characteristics: A multicenter retrospective study.

BACKGROUND: The prognosis of pediatric Epstein-Barr virus (EBV)-associated hemophagocytic lymphohistiocytosis (EBV-HLH) varies. This study aimed to identify high-risk children early. PROCEDURE: Data from 264 children (0-14 years of age), diagnosed with EBV-HLH at six centers in China between January 2016 and December 2021, were analyzed. Patients were randomly divided into derivation (n = 185) and verification (n = 79) cohorts. A Cox regression model was used to explore risk predictors and establish a prognostic scoring system for death events that occurred during the follow-up period. RESULTS: Chronic active EBV infection (CAEBV) history (hazard ratio [HR] 1.82 [95% confidence interval, CI: 1.02-3.26]; p = .0441), plasma EBV-DNA more than 104  copies/mL (HR 2.89 [95% CI: 1.62-5.16]; p = .0003), pulmonary infection (HR 2.24 [95% CI: 1.06-4.75]; p = .0353), digestive tract hemorrhage (HR 2.55 [95% CI: 1.35-4.82]; p = .0041), and hypoxemia (HR 3.95 [95% CI: 2.15-7.26]; p < .0001) were independent risk factors. Accordingly, the CAEBV history, plasma EBV-DNA copy number, pulmonary infection hemorrhage of digestive tract, hypoxemia prognostic scoring system (CEPHO-PSS) were developed, which separated patients into low- (0-1 points), middle- (2-3 points), and high- (4-8 points) risk groups. Survival curves for the three groups exhibited statistically significant differences (p < .0001). Internal and external verification of CEPHO-PSS was performed using receiver operating characteristic (ROC) and calibration curves in the derivation and verification cohorts, respectively, confirming good accuracy and applicability. CONCLUSIONS: The CEPHO-PSS identified three risk groups with statistically significant differences in survival curves. It was based on the baseline characteristics, and can give clinicians a convenient check for risk prediction.

Haemophagocytic lymphohistiocytosis caused by GATA2 deficiency: a report on three patients.

BACKGROUND: Haemophagocytic lymphohistiocytosis (HLH) is a syndrome that occurs in patients with severe systemic hyperinflammation. GATA binding protein 2 (GATA2) is a transcription factor and key component in haematopoiesis and stem cell biology. CASE PRESENTATION: Three patients with HLH, one with Mycobacterium avium infection, one with Epstein-Barr virus (EBV) infection, and one with Mycobacterium kansasii infection, were all subsequently found to have a defect in the GATA2 gene through genetic testing. CONCLUSIONS: GATA2 deficiency syndrome should be considered in patients with myelodysplastic syndrome, nontuberculous mycobacterium infection and HLH. In addition, the GATA2 gene variant may be a genetic defect that could be the cause of the primary HLH. However, further studies are needed to confirm the role of GATA2 pathogenic variants in the pathogenesis of HLH.

L-DEP regimen is effective as an initial therapy for adult EBV-HLH.

We performed a single-center, prospective trial to investigate the efficacy of PEG- asparaginase combined with liposomal doxorubicin, etoposide, and methylprednisolone (L-DEP) as an initial therapy for Epstein-Barr virus driven hemophagocytic lymphohistiocytosis (EBV-HLH). None of the patients received any chemotherapy after the diagnosis of EBV-HLH between September 2019 and September 2021. The efficacy was evaluated 2 weeks and 4 weeks after initiating L-DEP primary therapy. Forty-seven eligible patients with EBV-HLH were enrolled. The overall response rate (ORR) was 80.9% (38/47, 12 in clinical CR, 26 in clinical PR) at 2 weeks after the L-DEP regimen; at 4 weeks, the ORR was 75.6% (34/45, 21 in clinical CR, 13 in clinical PR). EBV-DNA loads in blood and plasma were significantly decreased 2 and 4 weeks after the L-DEP regimen (P < 0.001). Ferritin, soluble CD25 (sCD25), triglycerides (TGs), and ultrasonic spleen longitude, and thickness were all decreased significantly 2 and 4 weeks after the L-DEP regimen (P < 0.001). Thus, the L-DEP regimen is an effective initial therapy for EBV-HLH. However, the L-DEP regimen was poor in terms of long-term prognosis and that allo-HSCT should be received as soon as possible once a complete response is achieved.

Clinical characteristics and treatment of NK/T-cell lymphoma-associated HLH.

Natural killer (NK)/T-cell lymphoma-associated hemophagocytic lymphohistiocytosis (NK/T-LAHLH) is a rare and life-threatening disorder. Its clinical characteristics and appropriate treatment options are unclear. This study aimed to investigate the clinical characteristics and treatment options for this disease. We retrospectively analyzed the clinical data of 84 patients with NK/T-cell lymphoma and compared the characteristics, treatment, and survival between patients with and without HLH. Patients in the NK/T-LAHLH group were more likely to be younger age and have hepatosplenomegaly, B symptoms, neutropenia, anemia, thrombocytopenia, elevated lactate dehydrogenase levels, reduced serum albumin levels, bone marrow involvement, Ann Arbor stage III/IV, and International Prognostic Index score ≥ 3. After multivariate analysis, it was found that elevated lactate dehydrogenase and Ann Arbor stage III/IV were risk factors for HLH in patients with NK/T-cell lymphoma. After 2 weeks of therapy, 78.6% (11/14) patients who received the L-DEP/DEP regimen achieved an overall response rate of HLH, which was higher than that in 42.9% (9/21) patients who received the VP-16 + dexamethasone-based regimen. NK/T-LAHLH patients had poorer survival than non-HLH-NK/TCL patients. For NK/T-LAHLH, the L-DEP/DEP regimen may have a better response rate than the VP-16 + dexamethasone-based regimens.

Epstein-Barr virus central nervous system involvement in Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis.

Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) is a common subtype of secondary HLH. EBV plays an important part in the course. EBV can cause central nervous system (CNS) infections, and there are few clinical studies on EBV-CNS infection in EBV-HLH patients. All patients who were diagnosed as EBV-HLH and underwent cerebrospinal fluid testing admitted to our center from January 2018 to December 2019 were retrospectively analyzed. Summarized the clinical data, evaluated treatment efficacy after intrathecal injection, and investigated the correlation between EBV-CNS infection with prognosis in EBV-HLH patients. Of 37 of 57 (64.9%) EBV-HLH patients has EBV-CNS infection. The survival of EBV-HLH patients without EBV-CNS infection was significantly better than that in EBV-CNS infection patients (P = 0.018). There were no statistically significant differences in sCD25, ferritin, ALT, AST, LDH, TB, WBC, Hb, and PLT counts between two groups (all P-values > 0.05). Higher EBV-DNA load in peripheral blood was correlated with EBV-CNS infection (P < 0.001). EBV-CNS infection is an independent risk factor affecting the survival of patients (P = 0.004). The CSF cell load of patients with and without EBV-CNS infection groups was significantly different (P = 0.024). Intrathecal injection with methotrexate combined with dexamethasone can effectively decrease CSF EBV-DNA load (P = 0.017) and CSF cell load (P = 0.025). EBV-CNS infection is an independent risk factor affecting prognosis in EBV-HLH patients. Therefore, EBV-CNS infection should cause concern for EBV-HLH patients. Cerebrospinal fluid testing is necessary for all patients. Methotrexate combined with dexamethasone intrathecal injection can be an effective treatment for EBV-CNS infection.

Ruxolitinib-combined doxorubicin-etoposide-methylprednisolone regimen as a salvage therapy for refractory/relapsed haemophagocytic lymphohistiocytosis: a single-arm, multicentre, phase 2 trial.

We performed a multicentre, non-randomised trial (NCT03533790) to investigate the efficacy of ruxolitinib combined with the doxorubicin-etoposide-methylprednisolone (Ru-DEP) regimen as a salvage therapy for refractory/relapsed haemophagocytic lymphohistiocytosis (HLH). All patients failing to achieve a complete or partial response 2 weeks after initial HLH-94/HLH-04 regimen or relapsed after remission were enrolled in the study between June 2018 and June 2019. The efficacy was evaluated 2 weeks after initiating Ru-DEP salvage therapy. Fifty-four eligible patients with refractory/relapsed (R/R) HLH were enrolled. One case could not be evaluated for efficacy. Excluding 12 patients who had previously received the DEP regimen, the overall response rate was 32 of 41 (78·0%) patients, with eight of 41 (19·5%) achieving complete response and 24 of 41 (58·5%) attaining a partial response. Of the R/R HLH patients who had previously received the DEP regimen, 7 of 12 (58·3%) achieved a partial response. Ferritin and soluble CD25 concentrations were significantly lower (P < 0·05), while the platelet count increased significantly (P = 0·034), and triglycerides decreased significantly (P = 0·002) compared with those before treatment. The Ru-DEP regimen may be a safe and effective salvage therapy, remaining effective in refractory/relapsed HLH following DEP treatment, especially in macrophage activation syndrome. In addition, the regimen can be considered for patients with contraindications to glucocorticoid, especially those with gastrointestinal bleeding.

Diagnosis and surgical treatment of primary isolated aggressive lumbar myeloid sarcoma: a rare case report and review of the literatures.

BACKGROUND: Myeloid sarcoma is a rare, extramedullary, solid tumor derived from immature myeloid cell precursors. It is most frequently accompanied by acute myelogenous leukemia, though infrequently found in non-acute myelogenous leukemia patients. The tumor may involve any part of the body, but the lumbar spine is seldom involved. The present case study aims to understand the diagnosis and surgical treatment of a rare primary isolated myeloid sarcoma of the lumbar spine causing aggressive spinal cord compression in a non-acute myelogenous leukemia patient. CASE PRESENTATION: A 29-year-old man complained of an aggressive radiating pain to the lower extremities and moderate dysuria with a Visual Analogue Scale score that gradually increased from 3 to 8. Lumbar enhanced magnetic resonance imaging and computed tomography revealed a lumbar canal lesion at lumbar spine L2 to L4 with spinal cord compression. A whole body bone scan with fused single photon emission computed tomography/computed tomography demonstrated abnormal 99mTc-methylene diphosphonate accumulation in the L3 lamina and spinous process. No evidence of infection or hematology disease was observed in laboratory tests. Due to rapid progression of the symptoms and lack of a clear diagnosis, decompression surgery was performed immediately. During the operation, an approximately 6.0 × 2.5 × 1.2 cm monolithic, fusiform, soft mass in the epidural space and associated lesion tissues were completely resected. The radiating pain was relieved immediately and the dysuria disappeared within 1 week. Intraoperative pathological frozen section analysis revealed a hematopoietic malignant tumor and postoperative immunohistochemistry examination confirmed the diagnosis of myeloid sarcoma. CONCLUSIONS: The primary isolated aggressive lumbar myeloid sarcoma is rarely seen, the specific symptoms and related medical history are unclear. Surgery and hematological treatment are effective for understanding and recognizing this rare tumor.

Ruxolitinib treatment for SR-aGVHD in patients with EBV-HLH undergoing allo-HSCT.

Ruxolitinib is a promising option for treating steroid-refractory acute graft-versus-host disease (SR-aGVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). In this study, we describe ruxolitinib treatment for SR-aGVHD in HSCT patients with Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) to evaluate its effectiveness. We evaluated the outcomes of 12 patients who received ruxolitinib for SR-aGVHD between January 2017 and March 2019. Of the 12 patients who received ruxolitinib, 7 patients achieved a complete response (CR), 3 had a partial response (PR), and 2 experienced treatment failure (TF). OS and CR rates were 83.3% and 58.3%, respectively. Moreover, CR was achieved by the six patients who had aGVHD with skin involvement. The mean time of steroid application in the patients who received ruxolitinib was 28.1 days. Median survival after HSCT was 64.6 weeks. The adverse effects of ruxolitinib included grades 3 to 4 neutropenia (n = 7) and grades 3 to 4 thrombocytopenia (n = 6). Cytomegalovirus reactivation was observed in three patients. A high rate of CR and short steroid application time of ruxolitinib as a salvage treatment were observed in HSCT patients with EBV-HLH. Consequently, from this study, it was determined that ruxolitinib is an optimal choice to treat SR-aGVHD in patients with EBV-HLH.

The role of allogeneic hematopoietic stem cell transplantation and Epstein-Barr virus infection on the treatment for child primary hemophagocytic lymphohistiocytosis patients with X-linked lymphoproliferative disease: A rare case report and family survey study.

XLP-2 is known as a rare primary immunodeficiency disease, which is characterized by the susceptibility to EBV infection and potential development into the pHLH. The existing studies believe that the dysfunction of XIAP represents one of the most significant pathogenic mechanisms of XLP-2, and allo-HSCT is regarded as a crucial treatment for the long-term survival in XLP-2 patients. In our present study, a 2-year-old male patient was diagnosed with XLP-2. After receiving chemotherapy by using HLH-2004 without allo-HSCT, he reached a complete remission, and his EBV load was brought under control. Our family survey revealed a novel frameshift mutation in the XIAP gene in this patient, as well as in his cousin and grandfather. Until now, the patient has been followed up for 22 months with no recurrence reported yet. Based on these findings, it is believed that for child pHLH patients with XLP-2, the treatment by controlling symptoms alone without allo-HSCT and with regular monitoring of EBV load could be conducive to a long-term survival.

Neurological symptoms of familial hemophagocytic lymphohistiocytosis type 2.

Hemophagocytic lymphohistiocytosis with central nervous system involvement is caused by inflammatory factor storms. The inflammatory factors invade the blood-brain barrier and further infiltrate brain tissue resulting in associated neurological and/or psychiatric symptoms in hemophagocytic lymphohistiocytosis with central nervous system involvement patients. This case report is based on a 14-year-old male patient who experienced intermittent dizziness and blurred vision about five years before admission as well as lower limb weakness and unstable walking approximately three years before admission. His brain MRI showed abnormal signals in the bilateral cerebellar hemisphere and vermis, right occipital lobe, and bilateral basal ganglia. The cerebrospinal fluid examination revealed an increase in nucleated cells, mainly monocytes, and elevated protein. He had no typical manifestation of hemophagocytic lymphohistiocytosis in the early stage, such as fever, cytopenia, or hepatosplenomegaly. He was misdiagnosed with meningoencephalitis or tuberculous meningitis. Perforin gene detection revealed a mutation in the PRF1 gene. The final diagnosis of type 2 familial hemophagocytic lymphohistiocytosis was made based on the neurological symptoms and genetic test. The possibility of hemophagocytic lymphohistiocytosis needs to be considered in patients with unexplained central nervous system symptoms, even if the patient does not have typical hemophagocytic lymphohistiocytosis symptoms, such as fever, cytopenia, or hepatosplenomegaly. We present the neurological symptoms of familial hemophagocytic lymphohistiocytosis type 2.

The inhibitory receptors on NK cells and CTLs are upregulated in adult and adolescent patients with secondary hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) includes primary HLH (pHLH) and secondary HLH (sHLH). Mutations that cause abnormal functions in natural killer (NK) cells and cytotoxic T lymphocytes (CTLs) are frequently identified in pHLH. However, why NK cells and CTLs exhibit abnormal functions in sHLH remains unclear. Here, we demonstrated that NK cells in sHLH exhibited a high expression of inhibitory receptor NKG2A and a low expression of activating receptor NKG2D. Besides, the expression of HLA-E on lymphocyte, the adaptor of NKG2A on NK cells, was elevated in sHLH. Moreover, CTLs in sHLH patients expressed a higher level of functional exhaustion markers PD-1, TIM-3 and LAG-3 as well as a lower secretion of IFN-γ and CD107a upon stimulation. In addition, the expression of MHC-I on lymphocytes was decreased. Taken together, our study indicates a potentially pathological mechanism of sHLH and may open up new avenues for the development of immunotherapies against sHLH.

Hemophagocytic Lymphohistiocytosis during the Postpartum Stage of Pregnancy: A Report of Eight Cases.

Haemophagocytic lymphohistiocytosis (HLH) is a rare and severe clinical syndrome that can be classified as either primary or secondary. Secondary HLH can be triggered by a variety of diseases. Pregnancy-related HLH has already been observed clinically. However, most of these cases occur during pregnancy. Considering that the periods before and after delivery have different clinical features, we presented the first case series of HLH that presented during the postpartum stage of pregnancy. From these cases, we concluded that postpartum HLH is a common form of pregnancy-related HLH. Patients with postpartum HLH may suffer more complicated pathogenesis. Cytopenia was not as common as in other types of HLH, but liver dysfunction was present in almost all cases. The standard therapy of HLH-94/04 was very effective, and the outcomes of postpartum HLH were better.

[Clinical analyses of 80 hemophagocytic lymphohistiocytosis patients with Epstein-Barr viremia].

OBJECTIVE: To analyze the clinical characteristics, treatment and prognosis of hemophagocytic lymphohistiocytosis (HLH) patients with Epstein-Barr viremia (EBV). METHODS: A retrospective study was conducted to analyze the clinical data of 80 HLH patients aged ≥ 14 years with EBV-DNA >1 000 copies/ml in peripheral blood from 2008 to 2013. RESULTS: There were EBV-HLH (n = 46), HLH-associated lymphoma (n = 30) and primary HLH (n = 4). Among the relevant laboratory parameters, inter-group statistical differences existed only in alanine transaminase (ALT) and aspartate aminotransferase (AST) (P = 0.021, 0.035). The median follow-up period was 2.0 (0.5-20.0) months. And the 1-month, 3-month, 6-month and 12-month overall survival rates were 58.8%, 37.5%, 29.7% and 19.6% respectively. CONCLUSIONS: HLH patients with EBV have a pernicious clinical course with a poor prognosis. And it makes little sense for distinguishing HLH-associated lymphoma from EBV-HLH through routine laboratory tests.

The efficacy and safety of chidamide in combination with etoposide and glucocorticoids for the treatment of hemophagocytic lymphohistiocytosis in adult patients: an open-label, single-center study.

Background: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition characterized by hyperinflammation and organ failure, with a high mortality rate. Current first-line treatments for adult patients have limited efficacy and significant toxicity. The novel selective histone deacetylase inhibitor (HDACi), chidamide, has shown promise in preclinical studies for the potential treatment of HLH. Methods: An open-label, single-center study was conducted to evaluate the efficacy and safety of chidamide in combination with etoposide and glucocorticoids for the treatment of HLH in adult patients. Seventeen patients who fulfilled at least five of the eight HLH-2004 criteria were enrolled and treated with the combination therapy. The primary outcome was overall response rate (ORR), and secondary outcomes included survival, safety and tolerability, and changes in laboratory indicators. Results: A total of 17 HLH patients who met the inclusion criteria were enrolled in this study, with a male to female ratio of 1.8:1. The age range at enrollment was 31 to 71 years old, with a median age of 52 years old. The ORR was 76.5% (13/17 patients), with a complete response (CR) rate of 17.6% (3/17 patients) and a partial response (PR) rate of 58.8% (10/17 patients). The median overall survival (OS) was not achieved, with OS at 6 months and 12 months being 81% and 65%, respectively. The median progression free survival (PFS) was not achieved, with PFS at 6 months and 12 months being 68% and 55%, respectively. Hematologic toxicities is the most common. Safety profile was favorable, with very few cases of grade 3/4 toxicities observed. The results showed that the levels of sCD25, platelets, aspartate aminotransferase, lactate dehydrogenase, and albumin in these patients were significantly improved 3 weeks after treatment. Conclusion: The addition of chidamide to etoposide and glucocorticoids may be a promising new treatment option for patients with HLH, with a high ORR, manageable safety profile, and significant improvement in laboratory indicators. Further research is needed to confirm these findings and determine the optimal dosing and duration of therapy.

PD-1 Blockade-Induced Hemophagocytic Lymphohistiocytosis, a Dilemma Therapeutic Outcome in 2 Patients with CAEBV: A Case Series.

Hemophagocytic lymphohistiocytosis (HLH), whether primary or secondary, is a rare and fatal clinical syndrome of uncontrolled immune activation and inflammatory cascade. Immune checkpoint inhibitors (ICIs) induced HLH has no standard diagnostic and treatment guidelines. Early diagnosis and appropriate treatment according to different disease backgrounds are crucial. Herein, we first report 2 cases of patients with chronic active Epstein-Barr virus infection (CAEBV) who developed HLH after the use of sintilimab, a monoclonal antibody against programmed cell death protein 1 (PD-1), and the DEP (liposomal doxorubicin, etoposide, methylprednisolone) chemotherapy regimen in combination with ruxolitinib were used to successfully control the disease.

Lymphocytes in Patients with Chronic Active Epstein-Barr Virus Disease Exhibited Elevated PD-1/PD-L1 Expression and a Prevailing Th2 Immune Response.

Background And Objectives: Chronic active Epstein-Barr virus disease (CAEBV) is a proliferative disease of EBV+ T or natural killer (NK) cells with an unclear pathogenesis. This study aimed to examine the frequency and exhaustion levels of lymphocyte subsets in patients with CAEBV to further investigate the pathogenesis. Methods: Using flow cytometry, we detected the frequency, expression levels of programmed cell death 1 (PD-1) and programmed death ligand 1 (PD-L1), and EBV infection status of peripheral T subsets and NK cells in patients with CAEBV and healthy individuals. Results: 24 patients and 15 healthy individuals were enrolled in this study. Patients showed notably higher expression levels of PD-1 and PD-L1 in peripheral T subsets and NK cells compared to healthy individuals (P < 0.05). EBV+ lymphocytes exhibited significantly higher PD-L1 expression levels than EBV- lymphocytes. Additionally, the frequency of effector memory T (Tem) cells was significantly increased in patients, and the PD-L1 expression level was positively correlated with the EBV load. Besides, helper T cell 2 (Th2) immune bias, also favoring EBV amplification, was found in patients, including increased Th2 cell frequency, enhanced response capacity, and elevated serum levels of associated cytokines. The distribution and PD-1 expression levels of peripheral T subsets returned to normal in patients who responded to PD-1 blockade therapy. Conclusions: The up-regulation of the PD-1/PD-L1 pathway of peripheral T and NK cells and Th2 immune predominance jointly promoted EBV replication and the development of CAEBV. PD-1 blockade therapy reduced the PD-1 expression level of lymphocytes and helped normalize the distribution of the T subsets.