A human lymphoid cell line secreting immunoglobulin G and retaining immunoglobulin M in the plasma membrane.

A selected clone, LA 85.2, of a human lymphoid cell line produces, mu gamma, and light chains. The cells secrete IgG but not IgM. Assembly of mu chains and light chains produces 8S IgM which is retained in the plasma membrane. IgM is produced at a slow rate and in lesser amounts than IgG. LA 85.2 cells produce a plasma membrane protein which can bind to antibody-antigen precipitates. It is suggested that this protein plays a role in holding the surface IgM in the plasma membrane.