B Cell Differentiation and the Origin and Pathogenesis of Human B Cell Lymphomas.

Immunoglobulin (IG) gene remodeling by V(D)J recombination plays a central role in the generation of normal B cells, and somatic hypermutation and class switching of IG genes are key processes during antigen-driven B cell differentiation in the germinal center reaction. However, errors of these processes are involved in the development of B cell lymphomas. IG locus-associated translocations of proto-oncogenes are a hallmark of many B cell malignancies. Additional transforming events include inactivating mutations in various tumor suppressor genes and also latent infection of B cells with viruses, such as Epstein-Barr virus. Most B cell lymphomas require B cell antigen receptor expression, and in several instances chronic antigenic stimulation plays a role in lymphoma development and/or sustaining tumor growth. Often, survival and proliferation signals provided by other cells in the microenvironment are a further critical factor in lymphoma development and pathophysiology. Most B cell malignancies derive from germinal center B cells, most likely due to the high proliferative activity of these B cells and aberrant mutations caused by their naturally active mutagenic processes.

Genetic Manipulation and Extended Culture of Human Germinal Center B Cells to Model Lymphomagenesis.

The germinal center (GC) is the stage of B cell differentiation that gives rise to a majority of B cell lymphomas. Here, we present an experimental coculture system for the ex vivo expansion and genetic manipulation of human GC B cells purified from discarded tonsil tissue. This system can be used to investigate the impact of defined genetic alterations, either individually or in combination, upon the growth and survival of human GC B cells in vitro. We provide examples of genetic combinations that lead to the immortalized growth of GC B cells in vitro, and others that result in malignant transformation in immunodeficient mice, allowing the creation of genetically bespoke, synthetic, human lymphoma models.

Quantitative modeling of signaling in aggressive B cell lymphoma unveils conserved core network.

B cell receptor (BCR) signaling is required for the survival and maturation of B cells and is deregulated in B cell lymphomas. While proximal BCR signaling is well studied, little is known about the crosstalk of downstream effector pathways, and a comprehensive quantitative network analysis of BCR signaling is missing. Here, we semi-quantitatively modelled BCR signaling in Burkitt lymphoma (BL) cells using systematically perturbed phosphorylation data of BL-2 and BL-41 cells. The models unveiled feedback and crosstalk structures in the BCR signaling network, including a negative crosstalk from p38 to MEK/ERK. The relevance of the crosstalk was verified for BCR and CD40 signaling in different BL cells and confirmed by global phosphoproteomics on ERK itself and known ERK target sites. Compared to the starting network, the trained network for BL-2 cells was better transferable to BL-41 cells. Moreover, the BL-2 network was also suited to model BCR signaling in Diffuse large B cell lymphoma cells lines with aberrant BCR signaling (HBL-1, OCI-LY3), indicating that BCR aberration does not cause a major downstream rewiring.

DEK regulates B-cell proliferative capacity and is associated with aggressive disease in low-grade B-cell lymphomas.

This study sheds light on the pivotal role of the oncoprotein DEK in B-cell lymphoma. We reveal DEK expression correlates with increased tumor proliferation and inferior overall survival in cases diagnosed with low-grade B-cell lymphoma (LGBCL). We also found significant correlation between DEK expression and copy number alterations in LGBCL tumors, highlighting a novel mechanism of LGBCL pathogenesis that warrants additional exploration. To interrogate the mechanistic role of DEK in B-cell lymphoma, we generated a DEK knockout cell line model, which demonstrated DEK depletion caused reduced proliferation and altered expression of key cell cycle and apoptosis-related proteins, including Bcl-2, Bcl-xL, and p53. Notably, DEK depleted cells showed increased sensitivity to apoptosis-inducing agents, including venetoclax and staurosporine, which underscores the therapeutic potential of targeting DEK in B-cell lymphomas. Overall, our study contributes to a better understanding of DEK's role as an oncoprotein in B-cell lymphomas, highlighting its potential as both a promising therapeutic target and a novel biomarker for aggressive LGBCL. Further research elucidating the molecular mechanisms underlying DEK-mediated tumorigenesis could pave the way for improved treatment strategies and better clinical outcomes for patients with B-cell lymphoma.

Effectiveness of fractionated rituximab in preventing tumor lysis syndrome in aggressive B-cell lymphoma: Insights from real-life clinical practice.

BACKGROUND: Tumor lysis syndrome (TLS) is a potentially life-threatening condition resulting from the rapid destruction of malignant cells, leading to electrolyte imbalances and severe complications, such as acute kidney injury, arrhythmias, and seizures. TLS can be managed through hyperhydration, urate-lowering treatments, and a steroid prophase strategy. AIMS: This study aims to explore the impact of fractionated rituximab, an anti-CD20 antibody, on the occurrence and severity of TLS during the initial cycle in patients with aggressive B-cell non-Hodgkin lymphoma (B-NHL). METHODS: Data was retrospectively collected from 94 of 186 patients. RESULTS: Among the 94 patients included in the analysis, the median age was 70. Histologies were diffuse large B-cell lymphoma (75%), Burkitt lymphoma (13%) and high-grade B-cell lymphoma (8%). The majority were at an advanced stage (93%) with a high IPI score (75%). Most patients received anthracycline-containing regimens (72%) and prophylactic allopurinol (83%) and/or rasburicase (26%). Steroid prophase was administered to 82% of patients. The study identified one clinical TLS case and six laboratory TLS cases. Significant TLS factors included BL histology, elevated baseline LDH (⟩500 U/l), and rasburicase usage. Infusion reactions were rare (3%). Median progression-free survival was 2.6 years, and 2-year overall survival was 33%, irrespective of TLS occurrence. CONCLUSION: In this real-life study, clinical TLS occurrence was low (1%). TLS appeared more frequent in BL but did not impact overall survival. Fractionated initial rituximab dosing in addition to preventive strategies is a feasible approach in preventing clinical TLS, warranting further prospective investigation.

Presumed solitary ocular lymphoma of large B-cell origin with Mott cell change in a dog.

A 4-year-old female Maltese dog was referred to our veterinary hospital with uveitis and conjunctivitis of the right eye. An ophthalmological evaluation revealed an intraocular mass that appeared to originate from the anterior uvea. Metastasis and regional invasion were not detected with CT examination. Enucleation of the right eye was recommended; however, the owner declined treatment. Six months later, the dog was re-presented with a right facial mass. At presentation, superficial lymph node enlargement was not appreciated, and no apparent alterations were noted on blood analysis or urinalysis. Computed tomography revealed an intraocular mass that invaded the surrounding tissues, including the frontal sinus. Presumed solitary ocular lymphoma with a large B-cell phenotype and Mott cell change was diagnosed via histopathological and immunohistochemical examination of a biopsy of the lesion. As the mass was too large for complete excision, neoadjuvant chemotherapy was administered. Complete remission was achieved using the L-COAP protocol and successful exenteration of the right eye. However, the dog was returned with enlargement of the right retropharyngeal lymph nodes. To the best of our knowledge, this is the first case report of presumed solitary ocular lymphoma with a large B-cell phenotype displaying Mott cell change in a dog. Key clinical message: This is the first reported case of a presumed solitary ocular lymphoma with a large B-cell phenotype and Mott cell change. Although systemic involvement was observed 6 mo after the initial visit, neoadjuvant chemotherapy and exenteration were effective.

Lymphome oculaire solitaire présumé d'origine à grandes cellules B avec modification des cellules de Mott chez un chienUne chienne maltaise de 4 ans a été envoyée à notre hôpital vétérinaire avec une uvéite et une conjonctivite de l'œil droit. Une évaluation ophtalmologique a révélé une masse intraoculaire qui semblait provenir de l'uvée antérieure. Aucune métastase ni invasion régionale n'ont été détectées par examen CT. Une énucléation de l'œil droit a été recommandée; cependant, le propriétaire a refusé le traitement. Six mois plus tard, le chien a été présenté à nouveau avec une masse faciale droite. À la présentation, l'augmentation de taille des ganglions lymphatiques superficiels n'a pas été réalisée, et aucune modification apparente n'a été notée sur l'analyse sanguine ou l'analyse d'urine. La tomodensitométrie a révélé une masse intraoculaire qui a envahi les tissus environnants, y compris le sinus frontal. Un lymphome oculaire solitaire présumé avec un phénotype à grandes cellules B et une modification des cellules de Mott a été diagnostiqué via un examen histopathologique et immunohistochimique d'une biopsie de la lésion. Comme la masse était trop importante pour une exérèse complète, une chimiothérapie néoadjuvante a été administrée. Une rémission complète a été obtenue grâce au protocole L-COAP et à une exentération réussie de l'œil droit. Cependant, le chien a été vu de nouveau avec une hypertrophie des ganglions lymphatiques rétropharyngés droits. À notre connaissance, il s'agit du premier cas rapporté de lymphome oculaire solitaire présumé avec un phénotype à grandes cellules B présentant une modification des cellules de Mott chez un chien.Message clinique clé :Il s'agit du premier cas rapporté de lymphome oculaire solitaire présumé avec un phénotype à grandes cellules B et une modification des cellules de Mott. Bien qu'une atteinte systémique ait été observée 6 mois après la visite initiale, la chimiothérapie néoadjuvante et l'exentération ont été efficaces.(Traduit par Dr Serge Messier).

[Assessment of diagnostic utility of cerebrospinal fluid flow cytometry immunophenotyping and cytology in B cell non- Hodgkin lymphoma in a public chilean hospital]. / Evaluación de la utilidad diagnóstica de la citometría de flujo y la citología para el diagnóstico de compromiso de líquido cefalorraquídeo en linfomas no Hodgkin B en un hospital público chileno.

Cerebrospinal fluid (CSF) involvement in B cell non-Hodgkin lymphomas is a poor prognostic sign and diagnosis is made using techniques such as flow cytometry (FCM) and conventional cytology (CC). AIM: To evaluate the frequency of CSF involvement in B-NHL by both techniques in a public hospital. MATERIAL AND METHODS: 97 CSF samples were analyzed in tubes with cell preservative belonging to 70 patients, 71% male, median age 56 years (18-85 years), with a diagnosis of B-NHL and risk of infiltration according to medical criteria. Most were patients from new diagnosis (89%), diffuse large B cell lymphoma (60%), and Ann-Arbor stage III-IV (77%). In 67 samples (69%), CC and CMF were performed simultaneously. RESULTS: Of the samples analyzed by CMF, 99% were valuable, while by CC, only 67% (p<0,05). Globally, 25% of the samples showed infiltration by CMF, while 18% by CC (p<0,0001). Forty-four valuable samples were evaluable and analyzed by CC and CMF, finding a similar frequency of positive cases (27%), with two-thirds positive only by CC or CMF. Positive samples in diffuse large B cell lymphoma were 28% by CC and/or CMF. CONCLUSIONS: A higher proportion of infiltration cases were detected by CMF than by CC. In valuable cases, CC complements CMF.

Pediatric B-cell Non-Hodgkin Lymphoma: The Impact of Therapy Response and Relapse on Outcome. A Single-center Analysis.

BACKGROUND/AIM: Pediatric patients with primary refractory or relapsed B-cell non-Hodgkin lymphoma (B-NHL) have highly unfavorable prognosis. In this study, we retrospectively analyzed outcomes in pediatric B-NHL patients treated in a single center in Poland from 1995 to 2022, with emphasis on therapy results in patients with progression or relapse. PATIENTS AND METHODS: The primary objectives were a 5-year probability of overall survival (pOS) and a 5-year probability of event-free survival (pEFS). The secondary objectives involved the assessment of prognostic factors. RESULTS: A total of 76 children were eligible for the analysis. The 5-year pOS was 76.7%, and the 5-year pEFS was 72.9%. At diagnosis, elevated lactate dehydrogenase activity, the presence of B symptoms, bone marrow, skeletal or mediastinal involvement, and stage IV disease were associated with inferior outcomes. Nine children experienced progression and four relapse. The 5-year pOS for patients with progression was 38.1%. Two patients treated with hematopoietic stem cell transplantation (HSCT) as part of salvage therapy survived. However, only one out of seven patients who were treated without HSCT survived. The 5-year pOS was 0.0% in patients with relapsed disease. CONCLUSION: The most significant factor related to outcomes in pediatric B-NHL is therapy response, with a high mortality rate in children with refractory disease and relapse. There is no consensus on the salvage therapy approach; however, HSCT appears to be the optimal choice.

Clinical and Pathological Features of Primary Cutaneous Lymphomas in Nepal: A retrospective cohort study from a dermatology referral centre.

Background Primary cutaneous lymphomas (PCLs) are rare diagnoses in Nepal and are not well characterized till date. Objective To evaluate clinical and pathological features of Primary cutaneous lymphomas in Nepal. Method We retrospectively reviewed outpatient and inpatient records of a dermatology referral centre of Kathmandu, Nepal for clinical and pathological findings of cases diagnosed as cutaneous lymphomas from July 2010 through July 2020. The final diagnosis was made based on 2008 World Health Organization classification and its update 2018. Result There were 12 cases of Primary cutaneous lymphomas diagnosed during this period. The age of presentation ranged from 19 years to 81 years (Mean: 53.4 years ± 21.5 years, SD). There were ten cases of cutaneous T-cell lymphoma (CTCLs) and two cases of cutaneous B- cell lymphomas (CBCLs). Among cutaneous T-cell lymphoma, there were four cases of primary cutaneous anaplastic large- cell Lymphoma (PCALCL), two cases of classic (patch/plaque) mycosis fungoides (MF), two cases of folliculotropic mycosis fungoides (FMF), and one case each of primary cutaneous aggressive epidermotropicCD8+ T-cell lymphoma and lymphomatoid papulosis. Among cutaneous B- cell lymphomas, there was one case of primary cutaneous marginal zone B- cell lymphoma, and one case of primary cutaneous follicle centre lymphoma. Most cases of MF presented at stage IB (75%), and three patients of primary cutaneous lymphomas died during this period. Conclusion Primary cutaneous lymphomas appear to be very rare in this study and presentations ranged from classic Mycoses Fungoides to aggressive T-cell lymphomas. Cutaneous T-cell lymphomas appeared to be more common than cutaneous B- cell lymphomas in this study.

A highly selective PI3Kδ inhibitor BGB-10188 shows superior preclinical anti-tumor activities and decreased on-target side effects on colon.

PI3Kδ is a key signal transduction molecule in normal and malignant B cells, as well as in T-regulatory cells, making it a promising target for treatment of hematologic malignancies through both direct killing and anti-tumor immunity regulation. BGB-10188 is a highly selective inhibitor of PI3Kδ, showing more than 3000 folds selectivity over other PI3K isoforms and no significant inhibition across tested kinases. BGB-10188 potently inhibited PI3Kδ with IC50s ranging from 1.7-16 nM through various in vitro assays and showed a long-lasting and strong target inhibition in mouse B cells in vivo. BGB-10188 showed significant antitumor effects in human B cell lymphoma xenograft models as single agent or in combination with the BTK inhibitor zanubrutinib. BGB-10188 showed significant Treg inhibition in blood but not in colon, along with less drug accumulation in colon compared with idelalisib, which is an approved PI3Kdelta inhibitor with high incidence of gastrointestinal side effects in clinic. In summary, BGB-10188 is a novel PI3Kδ inhibitor with high selectivity, potency and improved safety profile shown in preclinical studies, which is showing the potential as a best-in-class PI3Kδ inhibitor.

Splenic cyst deroofing complicated with B lymphoma.

BACKGROUND: Splenic cysts are uncommon and very rarely malignant therefore their treatment isn't standardized. In case of symptomatic cysts different surgical approaches have been suggested. Primary malignant lymphoma of the spleen comprises less than 1% of non-Hodgkin's lymphomas. To our knowledge, only 203 cases of splenic large B-cell lymphoma (LBCL) have been reported to date and only 2 of them were fibrin-associated splenic cysts. CASE PRESENTATION: 27-year-old model with a 19 × 13 cm splenic cyst without data of malignancy in the preliminary study and therefore treated with laparoscopic deroofing. After histological diagnosis of LBCL with a fibrin/EBV-associated splenic pseudocyst, the patient received 4 cycles of Rituximab and a laparoscopic splenectomy was performed due to resurgence of the pseudocyst. No evidence of malignancy has been found during follow up (EBV viral load every 3 months during the first year, PET-CT every 6 months during the first year and annual afterwards) performed after the splenectomy. DISCUSSION AND CONCLUSIONS: The value of tumor markers and radiology for diagnosis of splenic cysts is put into question. Only 60 cases of Fibrin-associated LBCL (FA-LBCL) have been described in the literature therefore there are no treatment guidelines for them even though surgery together with systemic treatment has been the prevalent route with good results in most cases.

SETD1B mutations confer apoptosis resistance and BCL2 independence in B cell lymphoma.

The translocation t(14;18) activates BCL2 and is considered the initiating genetic lesion in most follicular lymphomas (FL). Surprisingly, FL patients fail to respond to the BCL2 inhibitor, Venetoclax. We show that mutations and deletions affecting the histone lysine methyltransferase SETD1B (KMT2G) occur in 7% of FLs and 16% of diffuse large B cell lymphomas (DLBCL). Deficiency in SETD1B confers striking resistance to Venetoclax and an experimental MCL-1 inhibitor. SETD1B also acts as a tumor suppressor and cooperates with the loss of KMT2D in lymphoma development in vivo. Consistently, loss of SETD1B in human lymphomas typically coincides with loss of KMT2D. Mechanistically, SETD1B is required for the expression of several proapoptotic BCL2 family proteins. Conversely, inhibitors of the KDM5 histone H3K4 demethylases restore BIM and BIK expression and synergize with Venetoclax in SETD1B-deficient lymphomas. These results establish SETD1B as an epigenetic regulator of cell death and reveal a pharmacological strategy to augment Venetoclax sensitivity in lymphoma.

Dexamethasone Inhibits the Growth of B-Lymphoma Cells by Downregulating DOT1L.

BACKGROUND: Dexamethasone (Dex), a synthetic glucocorticoid that acts by binding to the glucocorticoid receptor (GR), has been widely applied to treat leukemia and lymphoma; however, the precise mechanism underlying Dex action is still not well elucidated. DOT1L, a histone H3-lysine79 (H3K79) methyltransferase, has been linked to multiple cancer types, particularly mixed lineage leukemia (MLL) gene rearranged leukemia, but its contribution to lymphoma is yet to be delineated. Analysis from the TCGA database displayed that DOT1L was highly expressed in lymphoma and leukemia. RESULTS: We initially demonstrated that DOT1L served as a new target gene controlled by GR, and the downregulation of DOT1L was critical for the killing of B-lymphoma cells by Dex. Further study revealed that Dex had no impact on the transcriptional activity of the DOT1L promoter, rather it reduced the mRNA level of DOT1L at the posttranscriptional level. In addition, knockdown of DOT1L remarkably inhibited the B-lymphoma cell growth. CONCLUSIONS: Overall, our findings indicated that DOT1L may serve as a potential drug target and a promising biomarker of Dex sensitivity when it comes to treating B lymphoma.

MYD88 mutation-positive indolent B-cell lymphoma with CNS involvement: Bing-Neel syndrome mimickers.

MYD88 p.L265P mutation occurs in over 90% of Waldenström's macroglobulinemia (WM), which is characterized by lymphoplasmacytic lymphoma (LPL) with monoclonal IgM. WM requires careful diagnosis due to overlapping features with other B-cell malignancies. Bing-Neel syndrome (BNS), a rare complication of WM, involves central nervous system (CNS) invasion. This report describes two cases of morphologically low-grade B-cell lymphoma in the bone marrow accompanied by the presence of a large B-cell lymphoma in the brain and a common MYD88 p.L265P mutation, which were eventually established as BNS mimickers. Although the two components in these cases showed the same identical light-chain restriction, different immunoglobulin heavy-chain rearrangement peaks indicated distinct lymphoma stem cells for CNS and bone marrow lesions. These clinical cases emphasize the challenges in diagnosing BNS. Based on the findings, biopsy is recommended for accurate identification of the clonal relationship and MYD88 mutation status.

Enhancing cell death in B-cell malignancies through targeted inhibition of Bcl-3.

The t(14;19)(q32;q13) is a rare recurring translocation found in B-cell lymphoproliferative malignancies, involving the Bcl-3 gene. This chromosomal translocation is often found in patients under the age of 50 and causes a more progressive disease. The Bcl-3 gene encodes a protein belonging to the IκB family of proteins, which tightly regulates NFκB signaling by acting as an activator or repressor of transcription. Previously, we developed a second-generation Bcl-3 inhibitor that could directly interfere with Bcl-3 signaling pathway, resulting in reduced melanoma cell proliferation, invasion, and migration. The present study aimed to investigate the effect of a Bcl-3 inhibitor on B-cell lymphoma and leukemia cells. It was found that treatment of cells with this inhibitor caused a decrease in cell proliferation and cell survival. Furthermore, Bcl-3 inhibition in B-cell malignant cells resulted in the loss of mitochondrial membrane potential and functionality, as well as the increased expression of cleaved caspase 3, indicating that cell death occurs through the intrinsic apoptotic pathway. This observation is further supported by reduced expression of cIAP1 protein 1 (cIAP1) upon treatment of cancer cells. Given the current lack of clinical advancements targeting Bcl-3 in oncology, this opens a novel avenue for the development and investigation of highly specific therapeutic interventions against B-cell malignancies.

CD16+ as predictive marker for early relapse in aggressive B-NHL/DLBCL patients.

Assessing the prognosis of patients with aggressive non-Hodgkin B cell lymphoma mainly relies on a clinical risk score (IPI). Standard first-line therapies are based on a chemo-immunotherapy with rituximab, which mediates CD16-dependent antibody-dependent cellular cytotoxicity (ADCC). We phenotypically and functionally analyzed blood samples from 46 patients focusing on CD16+ NK cells, CD16+ T cells and CD16+ monocytes. Kaplan-Meier survival curves show a superior progression-free survival (PFS) for patients having more than 1.6% CD16+ T cells (p = 0.02; HR = 0.13 (0.007-0.67)) but an inferior PFS having more than 10.0% CD16+ monocytes (p = 0.0003; HR = 16.0 (3.1-291.9)) at diagnosis. Surprisingly, no correlation with NK cells was found. The increased risk of relapse in the presence of > 10.0% CD16+ monocytes is reversed by the simultaneous occurrence of > 1.6% CD16+ T cells. The unexpectedly strong protective function of CD16+ T cells could be explained by their high antibody-dependent cellular cytotoxicity as quantified by real-time killing assays and single-cell imaging. The combined analysis of CD16+ monocytes (> 10%) and CD16+ T cells (< 1.6%) provided a strong model with a Harrell's C index of 0.80 and a very strong power of 0.996 even with our sample size of 46 patients. CD16 assessment in the initial blood analysis is thus a precise marker for early relapse prediction.

Effect of Crocin and Crocetin Compared to Cyclophosphamide on the Expression Level of miRNA-16-1 in a B Cell Transformed with EBV Virus Cell Line.

INTRODUCTION: Crocin and Crocetin are compounds that have shown promising therapeutic potentials in various medical contexts. To date, the effect of crocin and crocetin on the expression level of miRNA-16-1 in Epstein Barr Virus (EBV)-induced lymphoma has not been investigated. This research delved into a comparative analysis of the cytotoxic effects of crocin and crocetin compared to cyclophosphamide, the main drug used in the treatment of lymphoma and PTLD, on B-cell lymphoma infected with EBV (cell line CO 88BV59-1). Additionally, the study examines the changes in miRNA-16-1 expression following these treatments in this cell line. MATERIALS AND METHODS: CO 88BV59-1 LCL cells were treated with crocin, crocetin (0.2 to 200 µM), and cyclophosphamide (0.05 to 50 µM) for 72 hours. Cell viability and apoptosis were assessed using resazurin and Annexin V/PI techniques, respectively. Additionally, the expression of miRNA-16-1-3p and miRNA-16-1-5p was determined using the Real-Time PCR method. The data were analyzed using one-way analysis of variance (ANOVA) with Tukey's multiple comparisons post-hoc test. RESULTS: Crocin and crocetin inhibited the proliferation and apoptosis caused by EBV-infected cells in a dose- and time-dependent manner (P<0.05). The expression levels of miRNA-16-1-3p and miRNA-16-1-5p remained unchanged in cells treated with crocin and crocetin. CONCLUSION: The study found that the cytotoxic effect of Crocin, Crocetin, and Cyclophosphamide on CO 88BV59-1 LCL is independent of the expression level of miRNA-16-1. The results showed a reduction in cell survival and an increase in cell death.

Exosomal miR-155-5p drives ibrutinib resistance in B-cell lymphoma.

Ibrutinib, a Bruton Tyrosine Kinase (BTK) inhibitor, has shown effectiveness against various B-cell lymphoid malignancies. However, prolonged usage can induce resistance, affecting treatment outcomes. The oncogenic microRNA, miR-155-5p, is associated with poor prognosis in B-cell lymphomas, prompting our investigation into the mechanism of acquired ibrutinib resistance in these cells. We generated ibrutinib-resistant OCI-Ly1 cells (OCI-Ly1-IbtR) through continuous exposure to 1 µM and 2 µM of ibrutinib. We conducted microRNA profiling of OCI-Ly1-IbtR and isolated exosomes via ultracentrifugation. Comparative studies of microRNA levels in cells and exosomes, as well as exploration of targets of up-regulated microRNAs in OCI-Ly1-IbtR, were performed. Target validation involved transfection of candidate microRNAs, and co-culture experiments utilized OCI-Ly1 cells with exosomes from OCI-Ly1-IbtR. Elevated levels of miR-155-5p were observed in OCI-Ly1-IbtR and its exosomes, correlating with AKT and NF-κB activation. Transfection of miR-155-5p induced AKT/NF-κB pathway activation in OCI-Ly1, resulting in ibrutinib resistance, enhanced colony formation, and sustained BTK activity. Primary cell lines from ibrutinib-refractory B-cell lymphoma patients exhibited similar signaling protein activation. Target evaluation identified KDM5B and DEPTOR as miR-155-5p targets, confirmed by downregulation after transfection. We observed KDM5B and DEPTOR enrichment in Ago2 during ibrutinib resistance and miR-155-5p transfection. Co-culture experiments demonstrated exosome-mediated transfer of miR-155-5p, inducing ibrutinib resistance and KDM5B/DEPTOR downregulation in OCI-Ly1. Our findings suggest that miR-155-5p overexpression is associated with AKT and NF-κB pathway activation in ibrutinib-resistant cells, proposing a potential role for acquired miR-155-5p upregulation in B-cell lymphoma ibrutinib resistance.