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Immunoglobulin expression in human lymphoblastoid cell lines with early B cell features
Immunoglobulin expression was studied by direct immunofluorescence and by biosynthesis experiments in two human cell lines Raji and T 5.1. The basic phenotype of these cells was close to that of pre-B cells: large cells with intracytoplasmic IgM with a predominance of mu chains over light chains and no detectable surface immunoglobulins. The apparent molecular weight of heavy and light chains was abnormally large. Immunoglobulins were secreted at a low rate as pentameric IgM in the T 5.1 line and as subunits and free light chains in the Raji line. Spontaneous variations of this phenotype were observed: the cultured cells acquired mu and lambda chains, then additionally delta chains while they progressively lost detectable cytoplasmic mu chains, thus leading to a mature B cell phenotype. Subsequently, the cells had no detectable surface and cytoplasmic immunoglobulins and then they displayed a pre-B cell phenotype again. Attempts to induce further maturation using various potential inducers were unsuccessful.
Immunoglobulin expression was studied by direct immunofluorescence and by biosynthesis experiments in two human cell lines Raji and T 5.1. The basic phenotype of these cells was close to that of pre-B cells: large cells with intracytoplasmic IgM with a predominance of mu chains over light chains and no detectable surface immunoglobulins. The apparent molecular weight of heavy and light chains was abnormally large. Immunoglobulins were secreted at a low rate as pentameric IgM in the T 5.1 line and as subunits and free light chains in the Raji line. Spontaneous variations of this phenotype were observed: the cultured cells acquired mu and lambda chains, then additionally delta chains while they progressively lost detectable cytoplasmic mu chains, thus leading to a mature B cell phenotype. Subsequently, the cells had no detectable surface and cytoplasmic immunoglobulins and then they displayed a pre-B cell phenotype again. Attempts to induce further maturation using various potential inducers were unsuccessful.