Michael Potter, a scientist at the National Cancer Institute whose research led to greater understanding of tumors and the immune system and who won the prestigious Lasker Award for medical research, died June 18 at his home in Bethesda, Md. He was 89.

He had acute myeloid leukemia, said his daughter, Melissa Adde Magrath.

Potter worked for more than 50 years at the National Cancer Institute, a branch of the National Institutes of Health in Bethesda, Md. He was a principal investigator in NCI’s Laboratory of Cell Biology and, for more than 20 years, was chief of the Laboratory of Genetics.

At its most basic level, Potter’s research focused on plasma cells, or a form of white blood cells that produce antibodies. In the 1950s, while studying laboratory mice, Dr. Potter learned that mineral oil injected in the bodies of mice could produce plasma cell tumors, or plasmacytomas.

He then studied the early stages of tumor development and the genetic factors contributing to the susceptibility and resistance to the growth of tumors. He was particularly interested in the development of antibodies, or blood proteins that battle disease within the body. Each of the plasma tumors, or plasmacytomas, produced a different antibody molecule.

“It was just game-changing research at that time,” said Beverly Mock, who was Potter’s successor at NCI’s genetics laboratory, on Saturday.

Potter freely shared his findings — and the strains of his mouse plasma cells — with scientists throughout the world, who paired his plasmacytomas with other forms of tissue. In the 1970s, two scientists at the University of Cambridge in England, Cesar Milstein and Georges Kohler, fused cells from a mouse spleen with the plasmacytomas developed by Potter.

The new cells created from this match produced monoclonal antibodies, or antibodies of a single molecular type, that can be replicated in unlimited quantities. The development of monoclonal antibodies is considered one of the most important advances in medical research of the 20th century. The antibodies can be used to measure the presence of hormones and proteins in the blood and have been widely used in the treatment of diseases, from cancer to arthritis to autoimmune disorders.

Because of their genetic purity, monoclonal antibodies can be used to target specific cells, including cancer cells. They have also led to a fuller understanding of the immune system.

In 1984, Milstein, Kohler and a third scientist, Niels Jerne, then working at a research institute in Switzerland, received the Nobel Prize in Physiology or Medicine for their work on monoclonal antibodies and the immune system.

Potter’s early work on tumors in mice had made their discoveries possible.

One month after the Nobel Prize announcement, Potter received the 1984 Lasker Award for basic medical research, presented by the Albert and Mary Lasker Foundation and considered second in importance only to the Nobel. The two scientists he shared the award with, Milstein and Kohler, had won the Nobel. Michael Potter was born Feb. 27, 1924, in East Orange, N.J. He spent much of his childhood in the shore town of Sea Girt, N.J., where he developed a lifelong love of fishing and the outdoors. His father was a lawyer who also worked as a graphic designer.

Potter graduated from Princeton University in 1945 and received his medical degree from the University of Virginia in 1949. He served in Korea as an Army medical officer during the Korean War.

Potter never expressed disappointment at not receiving the Nobel. Asked if his colleagues believed he should have shared in the prize, Mock, his successor at NCI’s genetics lab, said, “Absolutely.”