Properties of LTRCs and ITRCs. (A) Bone marrow cells were enriched first for Rho123^−/lowB220⁻CD3⁻ cells (sort 1) and then sorted for Sca-1⁺CD117⁺ cells (sort 2). Sca-1⁺CD117⁺ cells were further purified based on the expression of CD49b. Sorted LTRCs are Sca-1⁺CD117⁺lin⁻Rho⁻CD49b^−/low, and sorted ITRCs are Sca-1⁺CD117⁺lin⁻Rho^−/lowCD49b^{+/intermediate}. The example given shows a cell sort of WT bone marrow. (B) LTRCs and ITRCs purified from WT bone marrow were analyzed for their expression of TAC4 and NK-1 receptor by global RT-PCR. Total bone marrow cDNA was used as a positive control. β-actin was used to confirm the presence of equal amounts of cDNA. (C) Bone marrow “fractions A-F” were analyzed for their expression of TAC4 and NK-1 receptor mRNA. For B cell “fractions A-F,” bone marrow from 10 mice was pooled and stained with antibodies used to distinguish B-cell fractions. Enrichment was carried out in 2 independent sorts. In the first sort, B220⁺CD43⁺ live cells were gated and subsequently sorted for HSA⁻BP.1⁻ (fraction A), HSA⁺BP.1⁻ (fraction B), or HSA⁺BP.1⁺ (fraction C) populations. In the second sort, B220⁺CD43⁻ cells were gated and sorted for IgM⁻IgD⁻ (fraction D), IgM⁺IgD⁻ (fraction E), or IgM⁺IgD⁺ (fraction F) populations.