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