Crosslinking of the cell surface immunoglobulin (μ-surrogate light chains complex) on pre-B cells induces activation of V gene rearrangements at the immunoglobulin κ locus

Abstract

We constructed an expression vector encoding a truncated Ig μ chain that lacks both V_H and C_H1 domains (μΔm chain) and introduced the μΔm vector into the Ig negative Abelson pre-B cell line P17–27. The transfectants expressed a large amount of the μΔm chain on their surface, which was not complexed with the λ5 and VpreB surrogate light chain molecules. While P17–27 transfected with a vector for the intact μm chain (P17–27μm) shows V_κ rearrangements in culture, V, rearrangements were not detected in P17–27μΔm cells. When the μΔm chains on the cell surface were crosslinked by anti-μ antibodies, V_κ gene rearrangements were induced in P17–27 μΔm. These results strongly suggest that crosslinking of the μm-λ5-VpreB complex on the pre-B cell surface generates a signal that activates V_κ gene rearrangement, and that the λ5 and VpreB molecules are necessary for the spontaneous crosslinking of surface Ig on pre-B cells.