B-LCL-HROC59 Cells

B-LCL-HROC59 is an Epstein-Barr virus (EBV)-immortalized human B lymphoblastoid cell line generated from tumor-infiltrating B cells (TiBc) isolated from a primary colorectal carcinoma designated HROC59. The parental tumor was resected from an adult male patient with right-sided sporadic colorectal carcinoma and advanced-stage disease. Fresh tumor tissue was mechanically dissociated to obtain single-cell suspensions, and B cells were selectively immortalized in vitro using EBV-containing supernatant derived from the B95/8 marmoset cell line in the presence of cyclosporin A to suppress T- and NK-cell expansion. Long-term culture resulted in stable outgrowth of a monoclonal B-cell population, as demonstrated by immunoglobulin gene rearrangement analysis.

B-LCL-HROC59 secretes immunoglobulin G (IgG) as its exclusive isotype, with stable production over prolonged culture. In cell-based binding assays, IgG derived from B-LCL-HROC59 demonstrated only minimal binding to tested allogeneic colorectal carcinoma cell lines compared with other TiBc-derived IgGs exhibiting stronger tumor cell reactivity. No evidence of spontaneous B-cell outgrowth was observed in the absence of exogenous EBV during culture establishment, indicating that immortalization occurred in vitro rather than reflecting latent EBV-driven transformation in vivo. As a monoclonal, antigen-experienced tumor-infiltrating B-cell line, B-LCL-HROC59 provides a defined model for studying humoral immune responses within the colorectal cancer microenvironment and for investigating the specificity and functional properties of tumor-associated antibodies.