Must not have any positive result for anti-DNA antibodies as measured by standard testing procedures (anti-DNA antibody and anti-nuclear antibody (ANA) assays. This study does permit enrollment of volunteers with a low positive ANA (less than or equal to 1:160) titers, if there is no clinical evidence of underlying disorders that are associated with a positive ANA, if no first degree relative has an autoimmune disease, and if anti-DNA and ENA are negative.