Eva Klein (1925–2025)

Abstract

Before the discoveries of DNA structure and the genetic code, the function of nucleic acids, an abundant but mysterious cell component, was the subject of wide speculation. Studying the DNA content of Ehrlich carcinoma ascites cells — a considerable improvement from earlier studies on solid tumors — the Kleins found a correlation between the DNA content and growth properties of malignant cells. Subsequent studies showed that malignancy was associated with chromosomal abnormalities and permanent changes in histocompatibility and other genes. The studies culminated with the discovery, published in 1960, that the pretreatment of syngeneic mice with irradiated sarcoma cells inhibited the growth of methylcholanthrene-induced tumors. Tumor resistance was not achieved by pretreatment with irradiated normal cells, was specific for the challenging tumors, was abolished by total body irradiation before tumor challenge, and correlated with the inhibition of tumor cell growth by lymph node cells from the pretreated mice. The findings were the first conclusive evidence of endogenous tumor antigens and tumor-specific immune responses.

The Swedish Cancer Foundation saw the potential of the young couple and, through a national fundraising campaign, donated a new research building. Eva sketched a plan on a paper napkin that became the blueprint for the construction. In the Department of Tumor Biology, Eva and Georg created a dynamic and, in many aspects, unique research environment. At a time when modern tumor biology was in its infancy, the Department contributed fundamental discoveries in cancer genetics, tumor immunology, cell biology and virology. It became a sought-after destination for leading scientists from all over the world. In the early 1960s, Eva suggested researching a human tumor. The choice fell on Burkitt’s lymphoma, later shown to carry Epstein–Barr virus (EBV), the first known human tumor virus. A skilled experimentalist, she established several Burkitt’s lymphoma cell lines that were instrumental in the groundbreaking discovery of chromosomal translocations that activate the MYC oncogene.