Three-year randomised study of high-purity or intermediate-purity factor VIII concentrates in symptom-free HIV-seropositive hemophiliacs: effects on immune status - Seremitis, S V; Aledort, L M; Bergman, G E; Bona, R; Bray, G; Brettler, D; Eyster, M E; Kessler, C; Lau, T S; Lusher, J; Rickies, F (Lancet, 1993)