Tracking membrane and secretory immunoglobulina α heavy chain mRNA variation during B-cell differentiation by real-time quantitative polymerase chain reaction

Sue D. Xiang, Elizabeth M. Benson, Ian S. Dunn

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Primary transcripts for all Ig heavy chain isotypes are alternatively processed to encode either secreted or membrane forms of the same antibody and, in plasma cells, a shift towards the secreted form occurs. In principle, measuring the relative quantities of secreted and membrane forms for a particular isotype could monitor B-cell plasmacytoid differentiation. Ratios of α heavy chain mRNA secreted (αs) to membrane (αm) form were assessed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR; TaqMan) using an IgA plasma cell line (NCI-H929), a surface IgA + line (Dakiki) and human tonsillar B cells. While NCI-H929 cells showed the highest αs:αm ratio as expected, αs mRNA predominated for all unstimulated B cells and Dakiki cells. Treatment of B cells and Dakiki cells with IL-2 and IL-10 resulted in a further progression towards the αs form, correlating with increased human plasma cell antigen-1 (HPC1) mRNA levels. However,α mRNA processing and HPC1 expression were independently regulated, as IFN-γ treatment suppressed HPC1 levels while increasing αs:αm ratios. Cytokine-mediated increases in the αs:αm ratio resulted from strongly enhanced levels of αs with relatively constant αm values. Differentiation-related changes in mRNA processing can thus be tracked by automated quantitative PCR.

Original languageEnglish
Pages (from-to)472-481
Number of pages10
JournalImmunology and Cell Biology
Issue number5
Publication statusPublished - 1 Dec 2001
Externally publishedYes


  • α Heavy chain
  • B cell
  • Cytokines
  • Immunoglobulin
  • mRNA
  • Quantitative polymerase chain reaction

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