1. Department of Medicine Beth Israel Deaconess Medical Center Harvard Medical School Boston Massachusetts USA
2. Department of Immunology and Rheumatology Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán Mexico City Mexico
3. Current address: Medical Research Council Laboratory of Molecular Biology Cambridge UK
4. Current address: Division of Rheumatology University of Pennsylvania Philadelphia Pennsylvania USA
5. Escuela de Medicina y Ciencias de la Salud Tecnologico de Monterrey Mexico City Mexico