1. R. de Jong, D. G. Elferink, T. de Boer, T. H. M. Ottenhoff, Department of Immunohematology and Bloodbank, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, the Netherlands.
2. F. Altare and J-L. Casanova, INSERM Unité 429, Hôpital Necker-Enfants Malades,149, Rue de Sevres, 75743 Paris Cedez 15, France.
3. I.-A. Haagen and P. J. C. van Breda Vriesman, Department of Immunology, University Hospital Maastricht, P.O. Box 5800, 6202 AZ Maastricht, the Netherlands.
4. P. J. Kabel and J. M. T. Draaisma, Department of Medical Microbiology and Immunology, and Department of Pediatrics, St. Elisabeth Hospital, P.O. Box 747, 5000 AS Tilburg, the Netherlands.
5. J. T. van Dissel and F. P. Kroon, Department of Infectious Diseases, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, the Netherlands.