was noted between quantitative IgC, IgA, or IgM levels and various antibodies studied.Previous studies have clearly documented the increased prevalence of' both antilymphocyte and anti-RNA antibodies in the sera of family members as well as probands with systemic lupus erythematosus (SLE) (1-6). An apparent correlation was found between the presence of antilymphocyte antibody and close personal contact or association with the SLE proband (2). The present study was directed at a parallel examination of both antilymphocyte as well as antipolynucleotide antibodies in a completely different population group comprised of individuals related to a series of probands with clear-cut active SLE followed at the Institute of Rheumatology in Moscow, USSR. In addition the studies were extended to include data on antiviral antibodies in the hope that constellations of findings within such family groups might provide some evidence with regard to possible viral influence in the case of SLE. MATERIALS AND METHODSPatients and Families Studied. A total of 15 probands with SLE were selected for study. All of these subjects were patients under the hospital supervision of the Rheumatology Institute, Moscow, USSR. All patients with SLE met diagnostic criteria for SLE as recently proposed by ARA (7). An attempt was made to collect sera on all available living relatives of these SLE probands including both blood-related (consanguineous) and nonblood-related relatives. First-degree relatives included siblings, parents, and children of the pro-