Immunoglobulin synthesis by lymphoid cells transformed in vitro by Abelson murine leukemia virus

The majority of cell lines derived by infection of murine bone marrow cells with Abelson murine leukemia virus (A-MuLV) synthesize a μ chain but no detectable light chain. Aside from this μ-only phenotype, lines that make only light chain, both chains or no immunoglobulin-related polypeptides have also been found. Two lines have been studied in detail: one that makes only μ chain and one that makes only κ light chain. Synthesis of both polypeptides can be increased by modifying the culture conditions so as to decrease the growth rate of the cells. Although some κ chain secretion was observed, neither secreted nor surface μ was detected. We suggest that the μ-only phenotype may be an early normal step in the pathway of B lymphocyte maturation.