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 J_H 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-γ or -δ rearrangements, nor were TCR-δ rearrangements detected in CD10⁺/surface mu^- cells, despite the limited repertoire of these genes. These observations are surprising given the high frequency of TCR δ/γ 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.