There is controversy as to whether deletional rearrangement occurs between the IgM and IgE switch regions (S(μ) and S(ε), respectively) during switching to the IgE isotype. We have addressed the issue by stimulating normal human B cells, sorted for lack of expression of surface IgE, to produce IgE by infection with Epstein-Barr virus (EBV) in the presence of interleukin 4 (IL-4). Genomic DNA was amplified for S(μ)/S(ε) switch junction fragments by utilizing the nested-primer polymerase chain reaction. Switch junction fragments were amplified from B cells infected with EBV in the presence of IL-4 but not from B cells infected with EBV alone. The DNA sequence of these 'switch fragments' revealed direct joining of S(μ) to S(ε) in each case. The recombination sites within S(μ) were clustered within 900 base pairs at the 5' end of the switch region, suggesting that there are 'hot spots' for recombination within S(μ). The S(ε) recombination sites were scattered throughout the S(ε) region. These findings indicate that IL-4-induced isotype switching to IgE production in human B cells is accompanied by DNA rearrangements with joining of S(μ) to S(ε).
|Original language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Jan 1 1991|
- DNA rearrangement
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