1. Laboratory of Molecular Immunology, National Heart, Lung, and Blood Institute, Bethesda, MD 20892, USA.
2. Leukocyte Cell Biology Section, Laboratory of Experimental Immunology, Biological Response Modifiers Program, National Cancer Institute, Frederick, MD 21702-1201, USA.
3. Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, TN 38163, USA.
4. Division of Immunology and Allergy, Department of Pediatrics, University of Texas Medical Branch, Galveston, TX 77555-0369, USA.