Matching at the class I K locus between HSCs and recipient is critical for long-term self-renewal. HSCs (5000) were sorted from donors and transplanted into recipients that were disparate at selected MHC loci. (A) Shading shows the MHC disparity relative to B10.BR. (B) Survival curves of recipients disparate at class I D and L (B10.A[2R]); class I D and L with no class II I-E expression (B10.A[4R]), class I K, D, and L and class II I-A (B10.A[5R]), and class I K plus D and L (B10.MBR). (C) Survival of recipients of HSCs disparate at class I K plus class I D and L (B10.BR → B10.MBR) versus class I K only (B10.AKM → B10.MBR).