Immunology. In the article entitled “Murine natural killer cells contribute to the granulomatous reaction caused by mycobacterial cell walls” by I. Apostolou, Y. Takahama, C. Belmant, T. Kawano, M. Huerre, G. Marchal, J. Cui, M. Taniguchi, H. Nakauchi, J.-J. Fournié, P. Kourilsky, and G. Gachelin, which appeared in number 9, April 27, 1999 of Proc. Natl. Acad. Sci. USA (96, 5141–5146), the authors request that the following correction be noted: the title should be “Murine natural killer T (NKT) cells contribute to the granulomatous reaction caused by mycobacterial cell walls.”