Inverse correlation of Coombs antibody activities and Ht values in B6 × (NZB × B6.Yaa)F1 BC male mice bearing the Yaa mutation. 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. Each symbol represents an individual animal of BC Yaa males (n = 144). Linear regression line is indicated.