Immunoglobulin synthesis in the human myeloma cell line U-266; expression of two immunoglobulin heavy chain isotypes (epsilon and alpha) after long-term cultivation in vitro.
A human IgE-producing myeloma has been cultivated in vitro as a continuous cell line (U-266) since 1968. Analysis of immunoglobulin production during early passages of the cell line demonstrated a high synthesis rate of monoclonal IgE. Analysis of late passages, cultivated after 1980, revealed a 3-6-fold lower rate of IgE secretion. This decrease was accompanied by the appearance of small amounts of IgA in the culture medium together with IgE. RNA was extracted from a late passage of U-266 and analyzed by Northern blotting, using epsilon and alpha-specific oligonucleotides as hybridization probes. The results showed the presence of epsilon as well as alpha-specific mRNA. Moreover the results demonstrated that the latter mRNA was derived from the alpha 2 locus and that the epsilon and the alpha 2-specific mRNA contained the same V region sequences. Southern blot analysis of DNA from the late passage of the U-266 cell line failed to reveal a recombinatory switch from the epsilon locus to the alpha 2 locus. The expression of alpha 2 is thus likely to be caused by differential splicing rather than by an isotype switch at the DNA level.
D002460:Cell Line; D006801:Humans; D007118:Immunoassay; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis*; D007132:Immunoglobulin Isotypes / Q000096:biosynthesis*; D007137:Immunoglobulin alpha-Chains / Q000096:biosynthesis* / Q000235:genetics; D007139:Immunoglobulin epsilon-Chains / Q000096:biosynthesis*; D009101:Multiple Myeloma / Q000276:immunology* / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D010641:Phenotype; D012334:RNA, Neoplasm / Q000032:analysis; D014407:Tumor Cells, Cultured
D007143:Immunoglobulin Heavy Chains; D007132:Immunoglobulin Isotypes; D007137:Immunoglobulin alpha-Chains; D007139:Immunoglobulin epsilon-Chains; D012334:RNA, Neoplasm