Oakland Athletics outfielder Tim Raines, one of baseball's top base stealers and leadoff batters over a 20-year career, is suffering from lupus and will miss the rest of the season.

Raines, 39, who has been on the disabled list since July 19 with swelling in his kidneys, discussed his condition with his doctor at his side during an informal clubhouse news conference today.

Elliott Schwartz described lupus as a connective tissue disease in which the immune system turns against a person's own body.

"You might think of it as the body almost becoming allergic to its own tissues," Schwartz said. "In Tim's case, his body became almost allergic to his own kidneys, starting an inflammation process in those kidneys. We've given him medications to suppress that inflammation."

Raines, a member of the World Series champion New York Yankees last year, began the news conference with a declaration that he had no intention of quitting baseball. Schwartz said if the disease remains in remission, he could be ready for spring training next year.

There is no known cure for lupus but its symptoms can be treated.

"When you're sick and you're a ballplayer, you always feel a pill is going to make you better," Raines said. "But I think any time you get into a situation where it's maybe a life or death thing, you tend to think about it and wonder what you're going through.

"As baseball players, we kind of live a sheltered life, good, bad or ugly. I mean, you're on the top of the world. You feel like nothing can ever get to you. I think what I've gone through over the last three weeks, it's been pretty humbling, because I haven't been able to do the things I love to do and that's play baseball."

The A's players have inscribed Raines's No. 30 on their caps.

Raines, who broke into the majors in 1979 with Montreal, ranks first among active players in triples (112), second in stolen bases (807) and third in runs scored (1,548).

He was 6 for 18 (.333) as a pinch hitter this season but 2 for 15 over his last five games before going on the disabled list. He was batting .215 overall in 58 games.

Raines became bloated and mysteriously gained 15 pounds near the all-star break. A kidney biopsy was performed July 23. After an analysis was conducted at the University of California-San Francisco, he was told he had lupus.

Raines said he had never even heard of the disease until doctors told him he had it.

"I think it's always a relief to find out what's wrong with you," he said. "I know I never felt like that before."