Submitted March 15, 2006
Accepted September 19, 2006
CpG DNA activation and plasma cell differentiation of CD27- naive human B cells
Jennifer Huggins, Tina Pellegrin, Raymond E. Felgar, Chungwen Wei, Miguel Brown, Bo Zheng, Eric C.B. Milner, Steven H. Bernstein, Ignacio Sanz, and Martin S. Zand*
University of Rochester Medical Center
* Corresponding author; email: martin_zand{at}urmc.rochester.edu.
Unmethylated CpG DNA activation of naive CD27- B cells has been reported to require B cell receptor (BCR) cross-linking. We describe a culture system using CpG DNA with sequential steps for T cell independent activation of naive CD19+CD27- human peripheral blood B cells that induces efficient CD138+ plasma cell differentiation. CD27+ and CD27- Cells were cultured in a three step system: (1) Day 0-4: CpG + IL-2/10/15; (2) Day 4-7: IL-2/6/10/15 + anti-CD40L; (3) Day 7-10: IL-6/15, IFN-
, hepatocyte growth factor, and hyaluronic acid. Both CD27+ and CD27- B cells up-regulated intracytoplasmic TLR-9 following CpG DNA activation. CD27- B cell activation required cell-cell contact. Both naive and memory B cells progressed to a plasma cell phenotype: CD19lowCD20lowCD27+CD38+HLA-DRlow. 70% of the CD27- derived CD138+ cells demonstrated productive V chain rearrangements without somatic mutations, confirming their origin from naive precursors. Plasma cells derived from CD27+ B cells were primarily IgG+ while those from CD27- B cells were IgM+. Our results indicate that under some conditions naive B-cells increase TLR9 expression and proliferate to CpG DNA stimulation without BCR signaling. In addition to its immunological significance, this system should be a valuable method to interrogate the antigenic specificity of naive B-cells.
