Estelle Bettelli1,2, Daniel J Campbell3,4. 1. Benaroya Research Institute, Seattle, WA, USA. ebettelli@benaroyaresearch.org. 2. Department of Immunology, University of Washington School of Medicine, Seattle, WA, USA. ebettelli@benaroyaresearch.org. 3. Benaroya Research Institute, Seattle, WA, USA. dcampbell@benaroyaresearch.org. 4. Department of Immunology, University of Washington School of Medicine, Seattle, WA, USA. dcampbell@benaroyaresearch.org.