Coombs antibody activities and Ht values in B6.Yaa, (NZB × B6.Yaa)F1, and B6 × (NZB × B6.Yaa)F1 BC male mice. Coombs antibody activities and Ht values were determined at 10 months of age, and results are expressed as MFI for Coombs antibodies and as a percentage for Ht. Mean values are indicated by horizontal lines. Each symbol represents an individual animal of B6.Yaa (n = 18), (NZB × B6.Yaa)F1 (n = 16), and BC Yaa males (n = 144).