Immunoglobulin production by human lymphocytoid lines and clones: absence of genic exclusion

Immunoglobulin production was studied in established lines of normal human lymphocytes. Three lines which produced both immunoglobulin G and immunoglobulin M were cloned. Among the 25 immunoglobulin-producing clones, 23 produced both classes of immunoglobulins. These findings suggest that the phenomenon of genic exclusion does not hold for immunoglobulin production in lymphocytoid cells in culture.