precursor B cell pre-B-I cell A pre-B-I cell is a precursor B cell that expresses CD34 and surrogate immunoglobulin light chain (VpreB , Lambda 5 (mouse)/14.1 (human)) on the cell surface, and TdT, Rag1,and Rag2 intracellularly. Cell type carries a D-JH DNA rearrangement, and lacks expression of immunglobulin heavy chain protein. Human pre-B-I cells are reportedly CD10-positive, CD19-positive, CD22-positive, CD38-positive, CD45-low, CD79a-positive, CD127-negative, pre-BCR-negative, IgM-negative, IgD-negative, and Tdt-positive. Transcription factors expressed: Pax5-positive. cell pre-BI cell pro-B cell (Philadelphia nomenclature)