Analysis of immunoglobulin and T-cell receptor gene rearrangements in human fetal bone marrow B lineage cells

Fetal bone marrow B lineage cells representing multiple stages of B cell development were isolated by two-color cell sorting and analyzed for immunoglobulin H and T-cell receptor (TCR) gamma and delta gene rearrangements. Analysis of CD10+/surface mu- cells using a JH probe revealed a high frequency of rearrangements; some of these rearrangements used the 3′ D region gene DQ52. Analysis of CD10+/surface mu- cells revealed no detectable TCR-gamma or -delta rearrangements, nor were TCR-delta rearrangements detected in CD10+/surface mu+ cells, despite the limited repertoire of these genes. These observations are surprising given the high frequency of TCR delta/gamma rearrangements in B cell precursor acute lymphoblastic leukemia, and identify a potential difference in patterns of gene rearrangement that distinguish normal and leukemic B cell precursors.