Hematopoiesis in CD1d^−/− and Jα18^−/− mice. Comparative analysis of absolute numbers (A,C) and cycling status (B,D) of HPCs in BM (femur) and spleen of CD1d^−/− (cd1d1; C57Bl/6) and Jα18^−/− (C57Bl/6) mice and in the BM of CD1d1 (cd1d1 and cd1d2; C57Bl/6)^−/− (C-D) and Jα18^−/− (Balb/c) mice (C-D) compared with WT mice and sorting of myeloid progenitors mainly into the CD1d⁺ cell populations (E). Results in panels A and B are expressed as means ± SEM for 5 mice in each group and for 4 mice/group for panels C and D. For panel E, CD1⁺ or CD1⁻ BM cells were each plated at 5, 2.5, and 1.25 × 10⁴ cells/mL. Results are calculated from 1.25 × 10⁴ CD1⁺ and 5 × 10⁴ CD1⁻ cells/mL. Note that colony formation of 1.25 × 10⁴ CD1⁺ plus 1.25 × 10⁴ CD1⁻ cells/mL was equal to the sum of the individual populations alone (data not shown), suggesting that the results were not because of interactions of CD1⁺and CD1⁻ cells that either enhanced or suppressed colony formation. Significance levels compared with WT controls are shown in panels A through D; others are not significant (P > .05).