G Lorenzo, M Cepeda, M Ramos, D Saavedra, Z Mazorra, K Leon and T Crombet; clinical investigators (recruited and treated patients): LM Filgueira, JB Cervantes, OA Lovelle, C Herrera, C Figueredo, JA Caballero, N Sánchez, J Berrio, A Caballero; immunological assessments: