THURSDAY, Aug. 7 (HealthDay News) -- B cells may be more responsible for causing autoimmune diseases like lupus or rheumatoid arthritis than initially thought, according to a new study.

The finding, published in the Aug. 7 online issue of the journal Immunity, may give scientists a new path to pursue in finding ways to stop the immune system's chronic attacks on the body's own tissue during these diseases.

TUESDAY, May 13 (HealthDay News) -- Women who breast feed for more than one year reduce their risk of rheumatoid arthritis (RA) by half, according to a new Swedish study.

The researchers also found that having children but not breast-feeding offered women no protection against the disease.

Taking oral contraceptives also failed to reduce the risk of RA. It's been suspected that oral contraceptives offer protection against the disease because they contain hormones that are elevated during pregnancy.