Immunoglobulin synthesis and glucose-6-phosphate dehydrogenase as cell markers in human lymphoblastoid cell lines

Multiple lymphoblastoid cell lines were established from each of seven Burkitt lymphoma biopsies and from tonsils, removed from four patients with chronic tonsillitis. The cellular origin of the lines was studied using as markers the pattern of immunoglobulins secreted into the medium and the cells' glucose-6-phosphate dehydrogenase (G-6-PD) phenotypes.Lines from the same tonsil biopsy differed from each other by their patterns of immunoglobulin synthesis and G-6-PD phenotypes. All tonsil-derived lines secreted complete immunoglobulins. Newly established lines usually produced several heavy and light chain types, indicating multicellular origin, but the number of components produced decreased during the course of long-term cultivation. G-6-PD phenotypes of lines established from the same tonsil removed from a G-6-PD heterozygote differed—B, A and B/A phenotypes were found. The B/A lines rapidly changed to a single enzyme phenotype (B or A) when maintained in culture.The immunoglobulin and G-6-PD phenotypes in lines derived from Burkitt lymphomas differed from those of tonsil lines in several respects: (1) Some lines produced no immunoglobulins; (2) in immunoglobulin-synthesizing lines, the patterns of heavy and light chain production were more restricted than in tonsil lines; (3) after some months in culture, a uniform pattern of immunoglobulin synthesis was found in all lines derived from the same tumour; (4) lines from G-6-PD heterozygotes had the same single enzyme phenotypes as were found in the tumours.The data strongly suggest that most lines from Burkitt lymphomas are derived from the tumour clones and that most tonsil-derived lines have multicellular origin.     

THE DIFFERENTIAL SENSITIVITY OF CULTURED CHICK MESODERMAL CELLS TO ACTINOMYCIN D

Cells were isolated from the somite mesoderm and from the unsegmented (presomite) mesoderm of early chick embryos and exposed to actinomycin D in single cell culture. Actinomycin D inhibited proliferation in cell cultures derived from the unsegmented mesoderm, although the same concentrations of this antibiotic did not inhibit cultures derived from the somite mesoderm. This differential sensitivity parallels the regionally specific necrosis and degeneration observed in the unsegmented mesoderm of intact chick embryos exposed to actinomycin D. In culture, both cell types exhibited approximately the same permeability to labeled actinomycin D and showed comparable inhibition of RNA, DNA, and protein syntheses in the presence of the antibiotic. However, freshly isolated mesodermal cells from the somite region had a higher content of RNA than did cells from the unsegmented region, and the somite cells maintained a higher rate of macromolecular synthesis in untreated cultures.