B cell receptor (BCR) diversity and differential CDR3s usage as potential immune indictors of diffuse large B cell lymphoma (DLBCL) Running title: Vital roles of BCR traits in DLBCL

Abstract The aim of the present study was to characterize DLBCL of BCR distributions, and to screen specific BCR features as potential indicators related to DLBCL prognosis. A total of 13 patients with DLBCL and 5 healthy individuals were enrolled in the present study. In total, two high throughput sequencing methods, BCR repertoire and WES, were used to reveal BCR distributions and gene mutations, respectively. A series of comprehensive analyses were conducted to identify potential complementarity determining region 3 (CDR3) indicators of DLBCL and to analyze their association with clinical characteristics. The relatively higher BCR diversity in patients with DLBCL was associated with shorter progression-free survival (PFS). In addition, the top 10 differential CDR3s were screened as potential DLBCL indicators, and among these, four CDR3s [immunoglobulin heavy chain IGHV1-8/IGHJ6, IGHV3-74/IGHJ6, IGHV4-39/IGHJ3 and IGHV4-34/IGHJ4] exhibited a close relationship with PFS in patients with DLBCL. In further analysis, IGHV4-34/IGHJ4 and IGHV4-39/IGHJ3 were identified to be directly related to tumor metastasis, and IGHV4-39/IGHJ4 was related to hepatitis B virus (HBV) infection. WES data were used to analyze the gene mutations in patients with DLBCL, indicating that two metastasis pathways (‘focal adhesion’ and ‘ECM-receptor interaction’) were involved in characteristic changes of BCR. In conclusion, BCR diversity and usage of 10 specific CDR3s were identified as potential DLBCL indicators in the present study. Clinically, inflammation and HBV infection were the two main factors associated with changes of BCR characteristics. In terms of the molecular mechanism, BCR distributions were closely associated with metastasis-related pathways.