THE EXPRESSION OF V-PRE-B/LAMBDA-5 SURROGATE LIGHT-CHAIN IN EARLY BONE-MARROW PRECURSOR B-CELLS OF NORMAL AND B-CELL-DEFICIENT MUTANT MICE

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/lambda 5 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 C heavy chain (pH) is produced. The cell-cycle analysis revealed that cytoplasmic mu H+ large cells (large pre-B-II), similar to 30% of which coexpressed SL in the cytoplasm, were most actively cycling, whereas cytoplasmic mu H+ 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 mu H genes.