B-LCL-HROC68 Cells

B-LCL-HROC68 is an Epstein-Barr virus (EBV)-immortalized human B lymphoblastoid cell line established from tumor-infiltrating B cells (TiBc) isolated from a primary colorectal carcinoma designated HROC68. The parental tumor was a sporadic-type colorectal carcinoma resected from an adult male patient with advanced-stage disease. Fresh tumor tissue was mechanically dissociated, and B cells were cultured in the presence of EBV-containing supernatant derived from the B95/8 marmoset cell line, together with cyclosporin A to suppress outgrowth of T and NK cells. Long-term culture resulted in monoclonal expansion of B cells, as confirmed by immunoglobulin gene rearrangement analysis using BIOMED-2 multiplex PCR protocols, demonstrating a single dominant rearrangement pattern consistent with clonal origin.

B-LCL-HROC68 secretes immunoglobulin G (IgG) as its exclusive isotype, with stable production over extended culture. In cell-based ELISA screening against allogeneic colorectal cancer cell lines (HROC24, HROC46, and HCT116), IgG derived from B-LCL-HROC68 demonstrated measurable tumor cell binding, with the strongest signal observed against HCT116 cells. However, subsequent flow cytometric validation indicated comparatively weak binding affinity relative to other TiBc-derived IgGs. These findings indicate that B-LCL-HROC68 represents a monoclonal, antigen-experienced tumor-infiltrating B-cell line capable of producing functional IgG with detectable tumor cell reactivity, providing a useful in vitro tool for investigating humoral immune responses within the colorectal carcinoma microenvironment and for potential identification of tumor-associated antigens.