HBL-100 Cells

HBL-100 is a human breast epithelial cell line originally derived from the breast milk of a nursing mother. The milk was collected three days post-delivery, and despite no evidence of a breast lesion in the donor and no family history of breast cancer, the cells exhibited an abnormal karyotype by passage 7. This cell line is notable for its ability to synthesize a small amount of lactose and to respond to prolactin or estrogen stimulation by increasing the production of casein. Microscopic analyses, such as electron micrographs, have confirmed the presence of microvilli, tonofibrils, and desmosomes in these cells, highlighting their typical epithelial characteristics. However, the HBL-100 cell line has encountered significant complications regarding its identification and characterization. It was found to contain a Y chromosome, suggesting a misidentification as the cell line was initially thought to be of female origin. Further complexity arises from the presence of SV40 genomic sequences within the cell line, contradicting earlier beliefs that it was spontaneously immortalized. These findings have led to debates regarding the origin and the genetic makeup of HBL-100, making it a problematic cell line for research without thorough validation of its characteristics and origin.