The expression of V pre-B/λ5 surrogate light chain in early bone marrow precursor B cells of normal and B cell-deficient mutant mice

Abstract

Precursor B (pre-B) cells in bone marrow of normal and B cell-deficient mutant mice were analyzed for the expression of V pre-B/λ5 surrogate light chain (SL). The surface expression of SL is confined to the early stages (pro-B and pre-B-I) of pre-B cell development and becomes undetectable once μ heavy chain (μH) is produced. The cell-cycle analysis revealed that cytoplasmic μH + large cells (large pre-B-II), ∼30% of which coexpressed SL in the cytoplasm, were most actively cycling, whereas cytoplasmic μH + small cells (small pre-B-II) were SL − and not in cycle. The analysis of pre-B cells in B cell-deficient mice suggests that the large pre-B-II stage is a critical step for the selection and amplification of cells carrying functionally rearranged μH genes.