The HeLa cell line was the first immortal human cell line that George Otto Gey, Margaret Gey, and Mary Kucibek first isolated from Henrietta Lacks and developed at The Johns Hopkins Hospital in Baltimore, Maryland, in 1951. An immortal human cell line is a cluster of cells that continuously multiply on their own outside of the human from which they originated. Scientists use immortal human cell lines in their research to investigate how cells function in humans. Though the HeLa cell line has contributed to many advancements in biomedical research since the twentieth century, its usage in medical research has been controversial because Lacks did not consent to having her cells used for such purposes. As of 2020, scientists continue to use the HeLa cell line for numerous scientific advancements, such as the development of vaccines and the identification of many underlying disease mechanisms.

A lymphoblastoid cell line, or LCL, is an immortalized population of cells derived from a specific type of white blood cell called a B lymphocyte that scientists around the world began using for biomedical research in the late 1960s. By immortalized, scientists mean that the cells have been altered so they can grow and divide indefinitely, or at least for an extended period of time. That trait of LCLs makes them useful as a replenishable source of cells and the DNA contained within them. Scientists obtain LCLs by first collecting a blood sample and then exposing the B lymphocytes in the blood to Epstein-Barr virus, or EBV. EBV alters the B lymphocytes in such a way that the cells begin to multiply without restraint. Researchers began making and storing LCLs from individuals around the world in the 1960s. As of 2025, LCLs form a mainstay of biomedical research, especially in human genetics and genomics.