RESEARCHERS at Leicester University have identified a link between sunlight and the crippling disease lupus. Lupus, which affects more than 20,000 people in the UK, occurs when the body's immune system becomes overactive and attacks its own tissue. "Some patients' symptoms worsen greatly on exposure to sunlight," said chemical pathologist Karl Herbert. "This finding is proving useful in our investigations into the mechanisms of lupus." The research will be supported for the next three years by a Pounds 91,000 grant from the Arthritis and Rheumatism Council.