Al Rose has been a bodyguard to Leon Trotsky, an apprentice to muralist Diego Rivera and a successful caricaturist for more than 50 years.

But his pasion is New Orleans music. He's written books about it, collected sheet music, band arrangements, photographs and records and produced radio and television programs about it.

"Most of the things I've done by default because nobody else wanted to do them," he says with a hearty laugh. "I interviewed all those New Orleans musicians and people who are no longer here. No one could do those books now because those people aren't around."

Recently Rose and his wife, Diana, a musician and teacher, were guests at a Kennedy Center reception for a new Smithsonian traveling exhibition, "Played With Immense Success," about Louisiana popular music.

Much of the sheet music in the exhibit on view in the Center's North Gallery through Feb. 24, comes from the Al Rose Collection at the Tulane University Library. Rose, 63, has been collecting since he was 7. ("I never thought of it as collecting -- I thought it was more like accumulating").

He owns 36,000 band arrangements dating from 1890 to 1950, 2,000 rags in sheet music form, 3,000 photographs and 1,500 books. His collection has been used in more than 100 doctoral dissertations on music, architecture and literature.

Rose's first book was "New Orleans Jazz: A Family Album," co-written with Edmond Souchon. Next came "Storyville, New Orleans: Being an Authentic Illustrated Account of the Notorious Redlight District."

The later, drawn from the recollections of former prostitutes, formed the basis for "Pretty Baby," the 1978 Louis Malle movie about life in a fashionable bordello in the early part of the century.

Rose's latest book is a biography of pianist and ragtime composer Eubie Blake. Another, due out this spring, is about famous people born in New Orleans. And he has just finished a book about Lulu White, the famous New Orleans madam.

The writer, who looks like a slightly leaner Orson Welles, spears another clam in the Kennedy Center Restaurant."You know, I can't get clams in New Orleans because the water's too warm," he says.

Rose's forebears arrived in Louisiana with LaSalle. They made their fortune in sugar and cotton brokerage. A grandfather owned the Dauphine Theater, the main stage for vaudeville in New Orleans. His father, a cotton and sugar broker, accidentally invented cotton candy in 1921 while trying to develop a new sugar-refining procedure, and made another fortune in the process.

Rose made his break for freedom early. He refused to be confirmed as a Roman Catholic and ran away from home at age 14. He earned a living by drawing caricatures on the Mobile, Ala., boardwalk.

"I never got along with my family because they were hypocrites," he says. "They didn't practice their religion.They were insincere with people and they were very money conscious."

He returned to New Orleans as an 18-year-old but lived in a hotel. To this day he does not see any of his family.

In 1936, when he was 19, Rose produced the first jazz concert in Philadelphia, featuring Sidney Bechet, Sidney DeParis and Freddie "Gatemouth" Moore.

A year later he was off to Mexico City to study with Diego Rivera at the University of Mexico. Trotsky, the object of a massive manhunt by Stalin's secret police, lived with the muralist.

"I'm not too eager to publicize the fact that I was a bodyguard for Trotsky," said Rose, who looks as if he might have been a good one at 6 feet 1 1/2 and 198 pounds. "The Trotsky matter is irrelevant to my present activities. Most people don't know about it. The job was part of my tuition. And I lived with Rivera.

"There were 12 separate incidents in which we were fired on. I had a tooth shot out. And I had to use a variety of names. I was only 22."

Rose says he wasn't a Trotskyite. "But I had the conviction that he was doing important work," he explained. "I'm an orthodox Marxist-Leninist. And even though I'm not active now, I still assume the world is coming to a revolutionary socialist state."

Socialist or not, Rose has been an entrepreneur all of his life. For 46 years he's traveled to college campuses in Alabama, Mississippi, Louisiana and Georgia, drawing caricatures of fraternity and sorority members.

He's on the road about 14 weeks a year and says he earns approximately $3,000 a week. He figures he's done more than 400,000 caricatures.

He and his wife, a former whiz kid and former executive secretary of the Foundation for Gifted Children, raised two sons. One is chairman of the English department at the University of Maine. The other is head of a consortium of hospitals for geriatrics in Philadelphia.

Rose has stopped accumulating material. And he doesn't go out to hear music -- he only listens to records these days because that's where he can find the old-time New Orleans musicians.

He's also got a contract to write a history of jazz.

I've got enough projects on my desk to keep me busy for the next 200 years," he says with a big sigh.