At midday on a Saturday, the leader of the most prominent of all AIDS labs, Robert C. Gallo, sat in his sixth floor office fending off telephone entreaties. He needed a haircut, had several scientific discussions scheduled and had to finish an interview before he could leave.

Because acquired immune deficiency syndrome is a political and social issue -- as well as a scientific question -- Gallo's office is a lightning rod, the center of action and controversy on AIDS research in America.

The lab he leads at the National Cancer Institute in Bethesda has about 40 workers. Gallo himself does not spend his time at the lab bench or directly supervising workers. "I see my role as bringing the right people together, matching scientific problems to people personally, making flawed scientific suggestions," he said. "Then, when problems come up related to my suggestions, making more detailed scientific suggestions."

His most active moments in running the lab are in his more-or-less-weekly lab meetings. He caroms from city to city and nation to nation to attend meetings on AIDS, viruses and cancer, and then at the staff meetings reports back to his lab workers on the state of the art.

He also offers scientific ideas that he wants lab workers to check out. "He is very good at this," said one worker. "He has good instincts, he is a good sifter of information. I find what he brings back very useful. But he can sometimes be awfully sharp."

There seems to be a great distance between the present Robert Gallo, 48, renowned and flamboyant leader of science, and the boy who grew up in Waterbury, Conn. His father was a metallurgist and head of a welding business. His uncle was a PhD zoologist. When Gallo was 13, his younger sister got leukemia.

Gallo recalls one day when he opened his sister's door to look in on her. "She was emaciated . . . . she was yellow with jaundice. It was unbelievable," he said. "I was stunned. I almost passed out."

From the time in high school when he began visiting the lab of his sister's pathologist, Gallo has pursued essentially one subject, one disease whose human face he saw early -- leukemia. He and his coworkers made the crucial connection between the leukemia virus and the AIDS virus that has been the focus of most of the current research.

The discovery of the cause of AIDS was the third major scientific achievement for him and his coworkers. They discovered the first virus known to cause human cancer -- HTLV-1, which causes leukemia -- and found a "cell growth factor" called Interleukin-2. But it was AIDS that triggeed an international controversy.

The French government recently sued the United States, charging that Luc Montagnier at their Pasteur Institute, and not Gallo, first found the AIDS virus.

Gallo is tired of all the fury, but is caught up in it as one story adds to another, and as rumors become "facts" because they are published repeatedly. He is also caught up because he is a competitive, emotional man who has difficulty not fighting back.

"Gossip occurs about people who are visible, Period," he said. Parrying jabs and rumors "doesn't take up much time, except in talking to reporters. But it is the distress caused. It can give you a bad weekend sometimes."

He acknowledged that his personality sometimes fuels the debates. "I tend to be glib, and sometimes that gets me enemies," he said. Recently, he was criticized for his choice of five companies to make the AIDS antibody test. Gallo said he absolutely had no part in the choice.

Gallo said he recently told the Wall Street Journal: "I'm fed up with this kind of crap. Let me do some work in peace. These are just a bunch of dogs barking in the wind."