Researchers report genetic breakthrough

Techniques from the new frontier of the genetic sciences have helped researchers gain a significant insight into the intricacies of the human biological system.

They say the discovery may eventually yield major medical benefits.

An account published today in the British journal Nature reports that a 20 -year scientific quest to isolate one of the principal genes said to control the human immune system has ended in the lab of a team of researchers at Denver's National Jewish Hospital and Research Center.

According to the Denver research team, the gene provides the blueprint for a key immune-system protein called a T-cell receptor. Scientists say this protein controls the action of a group of white blood cells whose role, they indicate, is to rid the body of infected, malignant, or foreign tissues.

John W. Kappler, a director of the Denver team, says this finding will open the floodgates for basic research in a number of new but previously inaccessible areas. It will enable scientists to produce large amounts of human T-cell receptor protein in the laboratory, thereby, they say, providing them with a clearer understanding of how the immune system battles infections.

Dr. Kappler says scientists' aim is to learn how what he calls ''the body's powerful weapons'' might be harnessed to fight disease.

The discovery was made possible by gene sequencing, a decade-old process by which the structure of a specific gene is charted.

Genes, which scientists say enable traits to be carried on from generation to generation, are made of DNA, a double-stranded molecule that contains the complete plan of an organism. DNA itself is composed of four compounds - the ''letters'' of the chemical language.

Scientists say the way these letters are ordered determines the type of plan for which the DNA strand is encoded.

So by finding out the sequence of these letters, researchers say, they are able to tell precisely what kind of gene they are dealing with and what kind of protein it will help produce.

The technique has revolutionized molecular biology, where researchers try to chart the workings of the most complex biological processes. Because of it, many scientists say they are within 20 years of a complete understanding of the human central nervous system.

It has also spawned a multibillion-dollar industry that promises to revolutionize the agricultural and pharmaceutical industries.

Technicians are able to alter the sequence of DNA strands, a technique known as gene splicing and, through the process of cloning, have vast quantities of very pure ''custom-designed'' proteins available. Synthetic insulin derived from this process has been marketed for two years. Interferon, a drug produced in this manner that is used in cases of cancer, is currently being tested. And last month, British researchers announced the first cloning of Factor VIII, used in treating those medically diagnosed as hemophiliac.